Commodore PC 20-III CGA Composite
The Commodore PC 20-III is a XT-class 8088 clone PC running at 4.77 to 9.54MHz with 640KB of RAM. It also features an on-board Paradise PCV4 chip that provides CGA graphics on both D-Sub/RGBI and RCA/Composite connectors. While the RGBI worked fine, I could not get any picture with the composite connection.
I measured with both an oscilloskope and a multimeter and the composite signal was around 5 volts, which is not correct at all. Fortunately, circuit diagrams for this PC can be found on Bo Zimmerman's web pages, where I found something interesting:
There was a high chance the 5 volts came from the main VCC voltage rail through this transistor, which could be shorted. I confirmed a short circuit between collector and emitter using a multimeter and proceeded to remove the transistor. As expected the short was now gone. I did not have any 2N3904 in my stash, but used a BC549B as a replacement, which should be equivalent. Here is the replaced transistor in the middle:
I powered on the PC and measured with an oscilloscope again, which now shows a proper composite video signal:
I also ran the 8088 MPH demo to test for more colors on CGA:
Arduino Z80 CPU Tester
Here is a way to test Z80 CPUs that I created. I got the idea after seeing something about an Arduino being used as some sort of logic analyzer. For this I have used the Arduino Mega 2560 since this has a lot of digital I/O pins available.
It is a simple Arduino sketch, that uses the built-in USB CDC serial interface to communicate. It will respond to certain commands and on every cycle dump the status of the pins, which will look something like this:
|------\_/------|
0 | A11 A10 | 0
0 | A12 A9 | 0
0 | A13 A8 | 0
0 | A14 A7 | 0
0 | A15 A6 | 0
1 | CLK A5 | 0
0 | D4 A4 | 0
1 | D3 A3 | 0
0 | D5 A2 | 1
0 | D6 A1 | 0
- | +5V A0 | 1
1 | D2 GND | -
0 | D7 ~RFSH | -
1 | D0 ~M1 | -
1 | D1 ~RESET | 1
- | ~INT ~BUSRQ | -
- | ~NMI ~WAIT | -
- | ~HALT ~BUSAK | -
- | ~MREQ ~WR | 1
- | ~IORQ ~RD | 1
|---------------|
Address: 0x5 Data: 0xF
The commands available in this version is 'c' to toogle the CLK clock pin, 'r' to toggle the RESET pin and 0 through 7 to toggle the data bit pins. It is possible to easily expand on this, but these are the minimum pins required to make the sketch program useful. A simple test that can be done with the Z80 is to put 0xC3 on the data bit pins, and then just toggle the clock over and over. This will cause it to read the opcodes 0xC3 0xC3 0xC3, meaning an absolute jump to address 0xC3C3 which will get reflected back on the address pins.
There is no circuit diagram, instead use the #define in the Arduino sketch to determine the connections. In addition to the signals defined there, +5V and GND is also needed of course, gotten from the Arduino as well.
Here is the sketch:
#define PIN_A0 11
#define PIN_A1 12
#define PIN_A2 10
#define PIN_A3 61
#define PIN_A4 60
#define PIN_A5 59
#define PIN_A6 58
#define PIN_A7 57
#define PIN_A8 56
#define PIN_A9 55
#define PIN_A10 54
#define PIN_A11 62
#define PIN_A12 63
#define PIN_A13 64
#define PIN_A14 65
#define PIN_A15 66
#define PIN_D0 17
#define PIN_D1 16
#define PIN_D2 19
#define PIN_D3 69
#define PIN_D4 68
#define PIN_D5 21
#define PIN_D6 20
#define PIN_D7 18
#define PIN_CLK 67
#define PIN_RESET 8
#define PIN_WR 4
#define PIN_RD 3
void setup() {
Serial.begin(115200);
pinMode(LED_BUILTIN, OUTPUT);
pinMode(PIN_A0, INPUT);
pinMode(PIN_A1, INPUT);
pinMode(PIN_A2, INPUT);
pinMode(PIN_A3, INPUT);
pinMode(PIN_A4, INPUT);
pinMode(PIN_A5, INPUT);
pinMode(PIN_A6, INPUT);
pinMode(PIN_A7, INPUT);
pinMode(PIN_A8, INPUT);
pinMode(PIN_A9, INPUT);
pinMode(PIN_A10, INPUT);
pinMode(PIN_A11, INPUT);
pinMode(PIN_A12, INPUT);
pinMode(PIN_A13, INPUT);
pinMode(PIN_A14, INPUT);
pinMode(PIN_A15, INPUT);
pinMode(PIN_D0, OUTPUT);
pinMode(PIN_D1, OUTPUT);
pinMode(PIN_D2, OUTPUT);
pinMode(PIN_D3, OUTPUT);
pinMode(PIN_D4, OUTPUT);
pinMode(PIN_D5, OUTPUT);
pinMode(PIN_D6, OUTPUT);
pinMode(PIN_D7, OUTPUT);
pinMode(PIN_CLK, OUTPUT);
pinMode(PIN_RESET, OUTPUT);
pinMode(PIN_WR, INPUT);
pinMode(PIN_RD, INPUT);
}
void dump() {
uint16_t bus;
Serial.println(" |------\\_/------| ");
Serial.print(digitalRead(PIN_A11), DEC);
Serial.print(" | A11 A10 | ");
Serial.println(digitalRead(PIN_A10), DEC);
Serial.print(digitalRead(PIN_A12), DEC);
Serial.print(" | A12 A9 | ");
Serial.println(digitalRead(PIN_A9), DEC);
Serial.print(digitalRead(PIN_A13), DEC);
Serial.print(" | A13 A8 | ");
Serial.println(digitalRead(PIN_A8), DEC);
Serial.print(digitalRead(PIN_A14), DEC);
Serial.print(" | A14 A7 | ");
Serial.println(digitalRead(PIN_A7), DEC);
Serial.print(digitalRead(PIN_A15), DEC);
Serial.print(" | A15 A6 | ");
Serial.println(digitalRead(PIN_A6), DEC);
Serial.print(digitalRead(PIN_CLK), DEC);
Serial.print(" | CLK A5 | ");
Serial.println(digitalRead(PIN_A5), DEC);
Serial.print(digitalRead(PIN_D4), DEC);
Serial.print(" | D4 A4 | ");
Serial.println(digitalRead(PIN_A4), DEC);
Serial.print(digitalRead(PIN_D3), DEC);
Serial.print(" | D3 A3 | ");
Serial.println(digitalRead(PIN_A3), DEC);
Serial.print(digitalRead(PIN_D5), DEC);
Serial.print(" | D5 A2 | ");
Serial.println(digitalRead(PIN_A2), DEC);
Serial.print(digitalRead(PIN_D6), DEC);
Serial.print(" | D6 A1 | ");
Serial.println(digitalRead(PIN_A1), DEC);
Serial.print("- | +5V A0 | ");
Serial.println(digitalRead(PIN_A0), DEC);
Serial.print(digitalRead(PIN_D2), DEC);
Serial.println(" | D2 GND | -");
Serial.print(digitalRead(PIN_D7), DEC);
Serial.println(" | D7 ~RFSH | -");
Serial.print(digitalRead(PIN_D0), DEC);
Serial.println(" | D0 ~M1 | -");
Serial.print(digitalRead(PIN_D1), DEC);
Serial.print(" | D1 ~RESET | ");
Serial.println(digitalRead(PIN_RESET), DEC);
Serial.println("- | ~INT ~BUSRQ | -");
Serial.println("- | ~NMI ~WAIT | -");
Serial.println("- | ~HALT ~BUSAK | -");
Serial.print("- | ~MREQ ~WR | ");
Serial.println(digitalRead(PIN_WR), DEC);
Serial.print("- | ~IORQ ~RD | ");
Serial.println(digitalRead(PIN_RD), DEC);
Serial.println(" |---------------| ");
bus = digitalRead(PIN_A15);
bus <<= 1;
bus += digitalRead(PIN_A14);
bus <<= 1;
bus += digitalRead(PIN_A13);
bus <<= 1;
bus += digitalRead(PIN_A12);
bus <<= 1;
bus += digitalRead(PIN_A11);
bus <<= 1;
bus += digitalRead(PIN_A10);
bus <<= 1;
bus += digitalRead(PIN_A9);
bus <<= 1;
bus += digitalRead(PIN_A8);
bus <<= 1;
bus += digitalRead(PIN_A7);
bus <<= 1;
bus += digitalRead(PIN_A6);
bus <<= 1;
bus += digitalRead(PIN_A5);
bus <<= 1;
bus += digitalRead(PIN_A4);
bus <<= 1;
bus += digitalRead(PIN_A3);
bus <<= 1;
bus += digitalRead(PIN_A2);
bus <<= 1;
bus += digitalRead(PIN_A1);
bus <<= 1;
bus += digitalRead(PIN_A0);
Serial.print("Address: 0x");
Serial.print(bus, HEX);
Serial.print(" ");
bus = digitalRead(PIN_D7);
bus <<= 1;
bus += digitalRead(PIN_D6);
bus <<= 1;
bus += digitalRead(PIN_D5);
bus <<= 1;
bus += digitalRead(PIN_D4);
bus <<= 1;
bus += digitalRead(PIN_D3);
bus <<= 1;
bus += digitalRead(PIN_D2);
bus <<= 1;
bus += digitalRead(PIN_D1);
bus <<= 1;
bus += digitalRead(PIN_D0);
Serial.print("Data: 0x");
Serial.println(bus, HEX);
}
void loop() {
if (Serial.available() > 0) {
switch (Serial.read()) {
case 'r':
digitalWrite(PIN_RESET, digitalRead(PIN_RESET) ? 0 : 1);
break;
case 'c':
digitalWrite(PIN_CLK, digitalRead(PIN_CLK) ? 0 : 1);
break;
case '0':
digitalWrite(PIN_D0, digitalRead(PIN_D0) ? 0 : 1);
break;
case '1':
digitalWrite(PIN_D1, digitalRead(PIN_D1) ? 0 : 1);
break;
case '2':
digitalWrite(PIN_D2, digitalRead(PIN_D2) ? 0 : 1);
break;
case '3':
digitalWrite(PIN_D3, digitalRead(PIN_D3) ? 0 : 1);
break;
case '4':
digitalWrite(PIN_D4, digitalRead(PIN_D4) ? 0 : 1);
break;
case '5':
digitalWrite(PIN_D5, digitalRead(PIN_D5) ? 0 : 1);
break;
case '6':
digitalWrite(PIN_D6, digitalRead(PIN_D6) ? 0 : 1);
break;
case '7':
digitalWrite(PIN_D7, digitalRead(PIN_D7) ? 0 : 1);
break;
default:
break;
}
dump();
}
digitalWrite(LED_BUILTIN, digitalRead(LED_BUILTIN) ? 0 : 1);
delay(100);
}
The LED blinking is used as a indicator to see that the sketch program is actually running.
Here is a photo of the setup:
FAT16 File Extraction
This is a program I made as part of another bigger project, where I needed to read files from a FAT16 file system. It implements the bare-minimum to be able to extract a file from the root directory, and is only setup to handle the specifications of FAT16. (FAT12 or FAT32 will not work.) It can be used either on a disk image, or actually on a disk block device directly which does not need to be mounted. Calling the program with only the disk image argument will print the root directory, then add the target filename to dump that file.
Here is the code:
#include <stdio.h>
#include <stdint.h>
#include <string.h>
static void read_sector(FILE *fh, int no, uint8_t sector[])
{
fseek(fh, no * 512, SEEK_SET);
fread(sector, sizeof(uint8_t), 512, fh);
}
int main(int argc, char *argv[])
{
FILE *disk;
uint8_t sector[512];
uint32_t vbr_offset;
uint32_t fat_offset;
uint32_t root_dir_offset;
uint32_t data_offset;
uint8_t partition_type;
uint8_t sectors_per_cluster;
uint16_t reserved_sectors;
uint8_t no_of_fats;
uint16_t root_entries;
uint16_t sectors_per_fat;
char file_name[13]; /* 8.3 format at NULL byte. */
uint32_t file_size;
uint16_t file_cluster;
uint16_t cluster = 0; /* Target cluster for dump. */
uint32_t cluster_file_size;
uint16_t cluster_end_indicator;
uint16_t cluster_fat;
uint16_t cluster_offset;
if (argc <= 1) {
printf("Usage: %s <disk image> [dump file]\n", argv[0]);
return 1;
}
disk = fopen(argv[1], "rb");
if (disk == NULL) {
printf("Error: Unable to open: %s\n", argv[1]);
return 1;
}
read_sector(disk, 0, sector);
partition_type = sector[450];
vbr_offset = sector[454];
printf("First partiton type: 0x%02x\n", partition_type);
printf("First VBR @ 0x%x\n", vbr_offset * 512);
if (partition_type != 0x04 && partition_type != 0x06) {
printf("Error: First partition on disk is not FAT16!");
fclose(disk);
return 1;
}
read_sector(disk, vbr_offset, sector);
sectors_per_cluster = sector[13];
reserved_sectors = sector[14] + (sector[15] << 8);
no_of_fats = sector[16];
root_entries = sector[17] + (sector[18] << 8);
sectors_per_fat = sector[22] + (sector[23] << 8);
printf("Sectors per cluster: %d\n", sectors_per_cluster);
printf("Reserved sectors: %d\n", reserved_sectors);
printf("No of FATs: %d\n", no_of_fats);
printf("Root entries: %d\n", root_entries);
printf("Sectors per FAT: %d\n", sectors_per_fat);
fat_offset = vbr_offset + reserved_sectors;
root_dir_offset = fat_offset + (sectors_per_fat * no_of_fats);
data_offset = root_dir_offset + ((root_entries * 32) / 512);
printf("FAT Region @ 0x%x\n", fat_offset * 512);
printf("Root Directory Region @ 0x%x\n", root_dir_offset * 512);
printf("Data Region @ 0x%x\n", data_offset * 512);
printf("\nRoot Directory:\n");
for (uint32_t offset = root_dir_offset; offset < data_offset; offset++) {
read_sector(disk, offset, sector);
for (int i = 0; i < 512; i += 32) {
if (sector[i] == '\0') {
break; /* End of files. */
}
if (sector[i+11] & 0x10 || sector[i+11] & 0x08) {
continue; /* Subdirectory or volume label. */
}
int n = 0;
for (int j = 0; j < 8; j++) {
if (sector[i+j] == ' ') {
break;
}
file_name[n] = sector[i+j];
n++;
}
file_name[n] = '.';
n++;
for (int j = 0; j < 3; j++) {
if (sector[i+8+j] == ' ') {
break;
}
file_name[n] = sector[i+8+j];
n++;
}
file_name[n] = '\0';
file_cluster = sector[i+26] + (sector[i+27] << 8);
file_size = sector[i+28] +
(sector[i+29] << 8) +
(sector[i+30] << 16) +
(sector[i+31] << 24);
if (argc >= 3) {
if (strcmp(argv[2], file_name) == 0) {
cluster = file_cluster;
cluster_file_size = file_size;
}
}
printf("%12s (%d bytes) (cluster 0x%04x)\n",
file_name,
file_size,
file_cluster);
}
}
printf("\n");
if (cluster > 0) { /* Dump a file? */
FILE *out;
out = fopen(argv[2], "wbx");
if (out == NULL) {
printf("Failed to open file for writing: %s\n", argv[2]);
fclose(disk);
return 1;
}
read_sector(disk, fat_offset, sector);
cluster_end_indicator = sector[2] + (sector[3] << 8);
printf("Cluster end indicator: 0x%04x\n", cluster_end_indicator);
unsigned int bytes_written = 0;
while ((cluster >> 3) != (cluster_end_indicator >> 3)) {
printf("Read cluster: 0x%04x\n", cluster);
for (int s = 0; s < sectors_per_cluster; s++) {
read_sector(disk,
data_offset +
((cluster - 2) * sectors_per_cluster) +
s, sector);
bytes_written += fwrite(sector, sizeof(uint8_t),
(bytes_written + 512 > cluster_file_size)
? cluster_file_size - bytes_written
: 512, out);
}
/* Calculate next cluster. */
cluster_fat = cluster / 256;
cluster_offset = (cluster % 256) * 2;
read_sector(disk, fat_offset + cluster_fat, sector);
cluster = sector[cluster_offset] + (sector[cluster_offset + 1] << 8);
}
fclose(out);
}
fclose(disk);
return 0;
}
XP MCE Keyboard on Raspberry Pi Zero W
I have an old Remote Keyboard for Windows XP Media Center Edition which I have managed to "connect" to a Raspberry Pi Zero W through IR.
To get a IR functionality on the Pi, I followed these instructions and bought a Vishay TSOP38238 IR Receiver. This can be connected (or in my case soldered) directly to the GPIO header of the Pi.
|----------------|---------|---------------|
| | TSOP | Raspberry Pi |
| Name | 38238 | Zero W Header |
|----------------|---|-----|----|----------|
| Signal Data | 1 | OUT | 8 | GPIO14 |
| Ground | 2 | GND | 6 | Ground |
| Supply Voltage | 3 | VS | 1 | 3V3 |
|----------------|---|-----|----|----------|
To enable the GPIO pin 14 as IR the following must be set in /boot/config.txt on the Pi:
dtoverlay=gpio-ir,gpio_pin=14
To be able to configure the IR related mappings in the Linux kernel, the "ir-keytable" program must be installed:
sudo apt-get install ir-keytable
This XP MCE keyboard uses both the RC-6 protocol for multimedia buttons and a custom protocol of the regular keys, to enable both add this to /etc/rc.local on the Pi:
ir-keytable -p rc-6 -p mce_kbd
Now, this should have been enough to get it working, but in my case it didn't. I suspect there might be a bug/mismatch in either the Linux kernel itself or with the ir-keytable program. At the time of writing, the Pi is running kernel version 5.10.17+ and ir-keytable version 1.16.3. The problem I observed is that most of the keys on the keyboard does not send a EV_KEY event when monitoring with the "evtest" program, which in turn causes the key to not really work at all. After some debugging and troubleshooting I discovered that the affected keys are missing from the keybit[] array in the input_dev structure for the driver.
My solution to this is to patch the Linux kernel with a custom "ir-mce_kbd-decoder.ko" kernel module. To build this you will of course need the relevant Linux kernel sources for the Pi. Using this script and instructions seems to be the easiest way. The specific kernel version downloaded in my case was commit 3a33f11c48572b9dd0fecac164b3990fc9234da8.
Here is one way to build that single kernel module, assuming you have the kernel sources and the build tools installed:
mkdir ir-mce_kbd-decoder
cd ir-mce_kbd-decoder/
cp /home/pi/linux-3a33f11c48572b9dd0fecac164b3990fc9234da8/drivers/media/rc/ir-mce_kbd-decoder.c .
cp /home/pi/linux-3a33f11c48572b9dd0fecac164b3990fc9234da8/drivers/media/rc/rc-core-priv.h .
echo "obj-m := ir-mce_kbd-decoder.o" > Makefile
make -C /lib/modules/$(uname -r)/build M=$(pwd) modules
The ir-mce_kbd-decoder.c file needs to be patched with the following to set those missing bits in the keybit[] array:
--- ir-mce_kbd-decoder.orig 2021-10-17 12:28:27.991142273 +0200
+++ ir-mce_kbd-decoder.c 2021-10-17 13:18:46.908921902 +0200
@@ -360,11 +360,20 @@
static int ir_mce_kbd_register(struct rc_dev *dev)
{
+ int i;
struct mce_kbd_dec *mce_kbd = &dev->raw->mce_kbd;
timer_setup(&mce_kbd->rx_timeout, mce_kbd_rx_timeout, 0);
spin_lock_init(&mce_kbd->keylock);
+ for (i = 0; i < 256; i++) {
+ if (kbd_keycodes[i] != KEY_RESERVED) {
+ __set_bit(kbd_keycodes[i], dev->input_dev->keybit);
+ }
+ }
+ __set_bit(BTN_LEFT, dev->input_dev->keybit);
+ __set_bit(BTN_RIGHT, dev->input_dev->keybit);
+
return 0;
}
To load the new module temporarily for test, use the following commands:
sudo modprobe -r ir-mce_kbd-decoder
sudo insmod ir-mce_kbd-decoder.ko
sudo ir-keytable -p rc-6 -p mce_kbd
If it works fine, the module may be copied (and overwritten) to /usr/lib/modules/5.10.17+/kernel/drivers/media/rc/ir-mce_kbd-decoder.ko
CP/M on the GR-SAKURA
I have ported my "kaytil" Z80 CP/M 2.2 emulator to the Gadget Renesas GR-SAKURA reference board. This means it's possible to run all kinds of off-the shelf CP/M games and software on this board.
Even though it's based on the "kaytil" codebase, some heavy modifications have been done. All the trace and debug functions have been removed to reduce the binary size and also to speed up emulation. The Z80 emulation core remains the same but the console and disk emulations have been adapted to the different hardware. The CPM 2.2 and CBIOS binaries are embedded directly into the code to allow for easier standalone operation.
For the floppy disk emulation, the floppy disk images needs to be placed at the root directory on a FAT16 formatted MicroSD card (first partition) and be named "A.IMG", "B.IMG", "C.IMG" and "D.IMG" for each of the four drives. The MicroSD card on the GR-SAKURA is read through SPI and is kind of slow, so a simple caching mechanism has been implemented where the lowest sectors are cached in memory. To get optimal performance the FAT16 partition should be placed as close as possible to the MBR, possibly on sector 3, as this should get the actual FAT table cached into memory. Note that there is only read support, any writes to floppy disk by the CP/M OS are simply ignored. The four on-board LEDs on the GR-SAKURA are used as disk activity indicators.
For the console emulation I was first considering to use Renesas USB-CDC library to provide this over the USB connection, but I could not get it to work properly, as it seemed to get congested by too much traffic and just freeze. Instead, the first UART is used, marked by pins 0 (RX) and pin 1 (TX) on the GR-SAKURA, and it runs on 115200 baud for best performance. Same as the "kaytil" emulator on Linux; conversion between ADM-3A codes to VT100/ANSI codes are done in the emulator already. I wonder if it would have been technically possible to remove this conversion and connect a real Lear Siegler ADM-3A terminal (with a voltage level shifter) directory to the GR-SAKURA...
The RX CPU on the GR-SAKURA runs at 96MHz I believe, and compiling the emulator with -O2 optimization makes the speed nearly similar to a real Kaypro II, which is nice.
You can download the first version here and there is also a branch on the "kaytil" git repo.
Fujitsu FKB8530 Keyboard Repair
I got hold of a strange looking modular keyboard, the Fujitsu FKB8530, which I wanted to refurbish due to its unique construction. Unfortunately I discovered that it had sustained some kind of liquid damage, which in turn had caused corrosion on the membrane. The result was that some of the keys did not work. Measurements showed that the resistance had gotten too high between some of the points on one of the traces on the membrane.
I was able to repair this by gently scraping of the top layer on the membrane trace with a knife, then applying conductive silver paint (Loctite 3863 Circuit +) on top. I used regular Scotch tape to mask off the relevant area:
The keyboard after re-assembly:
Linux System on a Floppy
Referring to my previous project to build a Linux distribution for LOADLIN. It is actually possible to also boot this directly from a 1.44M floppy disk, which can be quite useful. The output from that build should be the Linux kernel "bzImage" and the root filesystem "rootfs.cramfs". I renamed "rootfs.cramfs" to simply "rootfs" to avoid any conflicts with the 8.3 filename format.
SYSLINUX will be used for booting, and it needs "syslinux.cfg" configuration file with the followng contents:
DEFAULT linux
LABEL linux
KERNEL bzImage
APPEND initrd=rootfs
These are the steps to make the floppy disk image:
dd if=/dev/zero of=floppy.img bs=512 count=2880
mkdosfs floppy.img
syslinux --install floppy.img
mkdir /tmp/floppy
mount -o loop floppy.img /tmp/floppy
cp bzImage /tmp/floppy/
cp rootfs /tmp/floppy/
cp syslinux.cfg /tmp/floppy/
umount /tmp/floppy
The floppy disk image can be tested in QEMU with:
qemu-system-i386 -fda floppy.img -boot a
Writing the floppy disk image to an actual floppy disk is typically done like so:
dd if=floppy.img of=/dev/fd0 bs=512
For convenience, download the floppy disk image here.
Tandon TM9362 Data Recovery
I have a Tandon TM9362 hardcard. Such hardcards are notorious for failing, a common problem is that the heads and other mechanical parts get stuck over time. Despite this I managed to fully recover the data from it. The actual hard drive on the card is a Tandon TM362, which is a 21MB MFM drive.
The shaft of the motor controlling the heads on these drives are actually accessible, which makes things easer. I managed to turn the shaft manually with my fingers to loosen it. Afterwards I applied 2 drops of "Bike Oil", which is similar to bearing oil, into the motor through the shaft and wiggled it some more. The card was then connected to a 486-class PC. Still, even with this oil applied it would not always power up on startup, but some more wiggling and power cycling made it spin up in the end.
This card contains it's own BIOS routines for accessing the disk, so I removed the existing hard drive on the PC to prevent any interference. It booted up with MS-DOS 3.20 and timestamps from 1990, so it could have been over 30 years since it was last accessed. I think MS-DOS 3.20 has issues with newer 1.44M floppy disks, so I booted DOS 5.0 from a floppy instead, still with the hardcard connected of course.
This PC has a 3Com 3C509 Ethernet card, so I loaded the Crynwr Packet Drivers for this and configured mTCP for TCP/IP networking. I setup the mTCP "ftpsrv" FTP server to host ALL files from the C: drive and used "ncftpget" from a Linux box to recursively download everything.
An additional cool but not really necessary step is to get those files onto a virtual disk image that can be loaded in QEMU. This particular hardcard has a CHS configuration of 615 cylinders, 4 heads and 17 sectors (per cylinder). Multiplying this with the standard sector size of 512 gives 41820, so a blank disk image can be made by:
dd if=/dev/zero of=tandon.img bs=512 count=41820
Importantly, in order for QEMU to properly forward the same CHS settings into the emulation, it needs to be specified on startup like so:
qemu-system-i386 -drive file=tandon.img,format=raw,if=none,id=dr0 -device drive=dr0,driver=ide-hd,cyls=615,heads=4,secs=17 -boot c
So actually get the files over I booted QEMU with the virtual disk image and another copy of a MS-DOS 3.20 floppy boot disk image that I found online. From the emulated DOS i ran the DOS "fdisk" and "format c: /s" to format the virtual disk in a compatible manner. Then I ran the Linux "fdisk" on the image and noticed the FAT partition was placed on sector 17 and onwards. Multiplying this by 512 gives 8704, so the partition on the virtual disk image can be loopback mounted like so:
sudo mount -o loop,offset=8704 tandon.img /tmp/tandon
Afterwards the recovered files can just be copied into the mounted loopback drive. The result is a bootable (in QEMU) virtual disk image with the correct MBR and VBR.
Amiga 500 with the Framemeister
Here is how I connected the Amiga 500 to the Micomsoft XRGB-mini Framemeister to be able to get color graphics on a modern display through HDMI.
The tricky part is getting a "DB23" connector, but I ended up using a regular DB25 connector (made from plastic) and shaving off part of it to make it fit into the Amiga 500. The mini-DIN connector on the Framemeister only accepts composite sync (not separate horizontal and vertical which is more common) but this is available on one of the pins on the Amiga. However, it is a 5V TTL level signal which is a little bit too hot so it's recommended to reduce this with a resistor. I ended up using two 360 Ohm resistors in series at 720 Ohm since that is what I found in stock at the moment. Some diagrams I found online claim that ground should be taken from pin 16 from the Amiga, but this did NOT work for me. Pin 19 which is composite video ground worked fine.
Here is the cable pin out:
|----------------|-------|---------|--------------|
| | Amiga | | Framemeister |
| Signal | DB23 | | Mini-DIN |
|----------------|-------|---------|--------------|
| Red | 3 | | 8 |
| Green | 4 | | 7 |
| Blue | 5 | | 6 |
| Composite Sync | 10 | 720 Ohm | 3 |
| Ground | 19 | | 4 |
|----------------|-------|---------|--------------|
When testing the connections with clip leads I got some "jail bars" (faint traces of vertical lines) on the display, but these more or less disappeared when I soldered everything together properly. Not sure if that was caused by general noise or by poor clip lead cables.
The finished cable connected:
Z80 CP/M 2.2 Emulator
After finishing a prototype of a MOS 6502 emulator I almost immediately started working on another one. This time a Zilog Z80 based one that runs CP/M 2.2 with inspiration taken from the Kaypro II computer, so I named the emulator "Kaytil".
Despite taking inspiration from the Kaypro II, it does not actually emulate any of the Kaypro II specific hardware, with the exception of the Lear Siegler ADM-3A compatible terminal emulation. But I think most Kaypro II software should work as long as it is not hardware specific and only expects the CP/M OS functionality. ADM-3A escape codes are converted directly to ANSI counterparts without going through (n)curses, which should be good enough.
To be able to run CP/M I adapted the skeletal CBIOS from Digital Research's manual to the emulator code, which is using IN/OUT instructions to communicate with each other. This, together with the reverse engineered CP/M 2.2 source from Clark A. Calkins is assembled using Digital Research's MAC macro assembler. Since the assembler is itself a CP/M program, I have run this in YAZE, which is another popular Z80 CP/M emulator.
Note that the Z80 emulation is not complete, but simply good enough, so some functionality is missing. I have made sure that it passes all the ZEXDOC tests for documented instruction flags, but I have made no effort so support the undocumented flags required to pass the ZEXALL tests. I also think the emulator is quite slow compared to others, probably due to ineffective O(n) instruction lookup and passing of data through functions instead of using global variables. In order for some games to run correctly, the speed is also artificially slowed down by using an interval timer, so it kind of matches that of a real Kaypro II. Some of these things can be adjusted by compile time defines though.
For storage, the emulator operates around on IBM 3740 8-inch floppy disk images. These can easily be managed with the Cpmtools package, which can create new images (mkfs.cpm) or copy files to and from them (cpmcp) from the host system. A total of 4 floppy drives (A, B, C & D) are emulated and can each contain its own image. By default the images are "read only" so any changes are not written back to the disk image file, but this can be overridden with the command line arguments.
Here are some games I have been able to run:
* Ladder (Yahoo Software, Kaypro II Version)
* Aliens (Yahoo Software, Kaypro II Version)
* CatChum (Yahoo Software, Kaypro II Version)
* Colossal Cave Adventure (Michael Goetz, Kaypro II Version)
* Sargon Chess (Hayden Books, CP/M Version)
* Deadline (Infocom, CP/M Version)
* Zork I (Infocom, CP/M Version)
* Zork II (Infocom, CP/M Version)
* Zork III (Infocom, CP/M Version)
* Nemesis (SuperSoft, CP/M Version)
The initial version can be gotten here but I have also put the source code on here for possible further development.
Finally, some screenshots of different games:
Retrobright Experiment
I finally got around to trying the Retrobright technique to remove yellowing. You need UV light, so doing this in Norway is a bit tricky because the weather is quite unpredictable and we do not have a lot of sun. Also, the Hydrogen peroxide (H2O2) needed is expensive and only comes in maximum 6% solution. I have an old computer mouse which was very yellowed and a perfect candidate for this experiment due to its small size.
There are several different methods and recipes to use for Retrobrighting, but I chose the plastic wrap method and using only H2O2 and corn starch. I put the 6% H2O2 into a cup and gradually added corn starch until I thought the mixture was thick enough. Afterwards I poured the mixture on the plastic wrap, put the yellow part of the mouse on the mixture and wrapped it together.
It was supposed to be a sunny day so I put the wrapped mouse outside at 08:30 in the morning, and then retrieved it at 18:30 in the evening, so it got around 10 hours of sunlight in total. All in all I was quite satisfied with the result.
Here is a picture showing the before and after and the different stages, you may notice the small bubbles appearing which is a sign the process is working.
Terminal Mode Commodore 64 Emulator
Just for fun I have made a primitive Commodore 64 emulator, or more correctly mostly a 6502 CPU emulator that happens to run the Commodore 64 ROMs with just a few tweaks. It was mostly to learn about the 6502 CPU itself, so if you actually need a proper emulator, then use VICE instead! The goal was to be able to load and run the Commodore BASIC ROM, which it does, in a Linux terminal.
Anyway, I am releasing the source code under the MIT license and it can be downloaded here.
The 6502 CPU is fully emulated and even supports decimal mode, although only with NMOS (not CMOS) compatibility, so the N, V and Z flags are not set correctly. Nevertheless it passes the excellent test suite made by Klaus Dormann, and even some of the tests made by Wolfgang Lorenz.
To support the C64 architecture, some simple memory bank switching support has been implemented, and hooks are placed when reading and writing to certain memory locations to capture the user input and output. The emulator blocks on input when waiting for a keyboard press, which is hugely beneficial to CPU load. I thought about using curses, but this makes things more complicated so the emulator sets the terminal into canonical mode (with no echo) for the BASIC editor to work instead.
To find the ROMs the emulator assumes that you have VICE installed from before, which puts these at "/usr/lib64/vice/C64/". The location can be changed by editing a #define if they happen to be elsewhere.
Here is what it looks like running in XTerm, and you can also see the CPU disassembly/trace and memory dump functionality embedded into the emulator:
FreeRTOS support for GR-SAKURA
I have managed to get FreeRTOS running on the GR-SAKURA board. Currently it's just a demo that blinks the LEDs, but maybe I will improve on that later. Anyway, this makes it possible to do multitasking. It is based code from the other FreeRTOS demos and some of the stuff from my earlier GR-SAKURA projects.
I started on this a while ago so the code is built around version 10.0.0 of FreeRTOS, but maybe it will work on newer versions as well.
Download the code from here and unpack the "GR-SAKURA" directory alongside the others into the "Demos" directory of FreeRTOS. Compile it by running "make" from that directory, but you will need the GCC toolchain for the Renesas RX CPU installed first.
I also finally got hold of the excellent Segger J-Link debug probe which makes it possible to use GDB ("rx-elf-gdb" from the RX GCC toolchain) to connect to the GR-SAKURA JTAG port, which I have soldered on:
Multiplayer Tank Game
Here is another game project I have had lying around for many years but never finished, until now that is. The idea was to make a graphical multiplayer game and the result is this game which lets up to 6 players drive a tank and shoot at each other. No emphasis on any advanced functionality, I just wanted to get this done and released. Note that a lot of trust is placed on the client here, which makes things simpler, but also makes it pretty easy to cheat by modifying the code.
The game is written in C and uses version 2 of the SDL library for graphics and sound. To make the networked multiplayer portion work, it uses the ENet reliable UDP networking library. It was created to be used on Linux, and I have not tried compiling and running it on other platforms. It probably works best on a local LAN, but I did test it through the Internet as well.
A screenshot:
The map data is stored as a text file that looks like this, easily edited:
################################################################
# # #
# # #
# # #
# T # T #
# # #
# # T #
# # ######### ########
# #
# #
# #
# #
# # #
# # #
# # T #
# # ########### #
# # # #
# # # #
# # # #
# # # #
# # ######### #
# # ######### #
# # ######### #
# T # ######### #
# # ######### T #
# # #
# # #
# # #
# # #
# # #
# # #
# # T # #
# # # #
# # # #
# # ################### #
# # #
# # ####### #
# #
# #
# #
######## # #
# T # #
# # #
# # #
# T # T #
# # #
# # #
################################################################
The source code is released under the MIT license and can be downloaded here.
DVB-T USB Stick Playback
I got one of those DVB-T tuners a while ago, in the form of a USB stick, specifically this one:
15a4:1001 Afatech Technologies, Inc. AF9015/AF9035 DVB-T stick
However, it took me many years to finally get this working on Linux after a lot of trial and error. There are two important things I discovered during this time. The first is that MPlayer is quite bad at handling MPEG TS files (or streams). The second is that, at least in my case with this particular stick, the /dev/dvb/adapter0/dvr0 device would not work as advertised.
The solution I ended up with is w_scan for scanning, v4l-utils for tuning and ffmpeg for playback.
Use these steps to scan and generate the channels list:
w_scan --output-initial > channels.conf
dvbv5-scan --input-format=CHANNEL --output=dvb_channel.conf channels.conf
Then use these steps for playback:
mkfifo /tmp/dvb.ts
dvbv5-zap -c dvb_channel.conf "name-of-the-channel" -o /tmp/dvb.ts &
ffplay /tmp/dvb.ts
I found that TV (video and audio) playback works OK, but radio (audio only) will buffer for a very long time before playback starts, so not very convenient.
Space Ship Simulator in OpenGL
I finally finished a project I had suspended many years ago when I was looking into OpenGL. At that time my solution had problems that I now later have discovered was related to the dreaded Gimbal lock caused by the use of Euler angles. The new solution uses rotation matrices directly. It uses the GLUT library which is kind of deprecated, but still very widely available and convenient for simpler OpenGL programs and demos like this one.
This space ship simulator is quite simple, but allows movement in all directions. When the program is started, the "universe" is populated with some randomly generated (really small) planets which can be navigated around. Use W/S to pitch, A/S to yaw, Z/C to roll and R/F to increase/decrease thrusters.
Here is the code, compile it like so: gcc -o space space.c -lGL -lGLU -lglut -lm -Wall
#include <GL/glut.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>
#define WORLD_SIZE 25 /* Distance to fake walls from origin. */
#define GRID_SPACING 5
#define GRID_START ((0 - WORLD_SIZE) + GRID_SPACING)
#define GRID_END (WORLD_SIZE - GRID_SPACING)
#define GRID_SIZE ((GRID_END - GRID_START) / GRID_SPACING)
#define PLANETS_MAX 10
#define PLANETS_CHANCE (GRID_SIZE * GRID_SIZE * GRID_SIZE) / PLANETS_MAX
typedef struct vector_s {
float x;
float y;
float z;
} vector_t;
typedef struct planet_s {
vector_t pos;
float size;
float color_r;
float color_g;
float color_b;
} planet_t;
typedef struct planet_distance_s {
int planet_index;
float distance;
} planet_distance_t;
static int camera_mode = 0;
static float ship_speed = 0.0;
static int old_mouse_x;
static int old_mouse_y;
static planet_t planets[PLANETS_MAX];
static int planets_count = 0;
static vector_t ship_forward_vector = {1,0,0};
static vector_t ship_up_vector = {0,1,0};
static vector_t ship_right_vector = {0,0,1};
static vector_t ship_position = {0,0,0};
static vector_t vector_normalize(vector_t v)
{
float magnitude;
vector_t normalized;
magnitude = sqrt((v.x * v.x) + (v.y * v.y) + (v.z * v.z));
normalized.x = v.x / magnitude;
normalized.y = v.y / magnitude;
normalized.z = v.z / magnitude;
return normalized;
}
static vector_t vector_cross_product(vector_t a, vector_t b)
{
vector_t cross;
cross.x = (a.y * b.z) - (a.z * b.y);
cross.y = (a.z * b.x) - (a.x * b.z);
cross.z = (a.x * b.y) - (a.y * b.x);
return cross;
}
static vector_t vector_multiply(vector_t v, float f)
{
vector_t product;
product.x = v.x * f;
product.y = v.y * f;
product.z = v.z * f;
return product;
}
static vector_t vector_sum(vector_t a, vector_t b)
{
vector_t sum;
sum.x = a.x + b.x;
sum.y = a.y + b.y;
sum.z = a.z + b.z;
return sum;
}
static vector_t vector_difference(vector_t a, vector_t b)
{
vector_t difference;
difference.x = a.x - b.x;
difference.y = a.y - b.y;
difference.z = a.z - b.z;
return difference;
}
static float vector_distance(vector_t a, vector_t b)
{
return sqrt(((a.x - b.x) * (a.x - b.x)) +
((a.y - b.y) * (a.y - b.y)) +
((a.z - b.z) * (a.z - b.z)));
}
static void ship_pitch(float angle)
{
ship_forward_vector = vector_normalize(
vector_sum(
vector_multiply(ship_forward_vector, cos(angle * (M_PI / 180))),
vector_multiply(ship_up_vector, sin(angle * (M_PI / 180)))));
ship_up_vector = vector_cross_product(
ship_forward_vector, ship_right_vector);
ship_up_vector = vector_multiply(ship_up_vector, -1.0);
}
static void ship_yaw(float angle)
{
ship_forward_vector = vector_normalize(
vector_difference(
vector_multiply(ship_forward_vector, cos(angle * (M_PI / 180))),
vector_multiply(ship_right_vector, sin(angle * (M_PI / 180)))));
ship_right_vector = vector_cross_product(
ship_forward_vector, ship_up_vector);
}
static void ship_roll(float angle)
{
ship_right_vector = vector_normalize(
vector_sum(
vector_multiply(ship_right_vector, cos(angle * (M_PI / 180))),
vector_multiply(ship_up_vector, sin(angle * (M_PI / 180)))));
ship_up_vector = vector_cross_product(
ship_forward_vector, ship_right_vector);
ship_up_vector = vector_multiply(ship_up_vector, -1.0);
}
static void ship_advance(float distance)
{
ship_position = vector_sum(ship_position,
vector_multiply(ship_forward_vector, distance));
}
#ifdef DEBUG_MODE
static void ship_ascend(float distance)
{
ship_position = vector_sum(ship_position,
vector_multiply(ship_up_vector, distance));
}
static void ship_strafe(float distance)
{
ship_position = vector_sum(ship_position,
vector_multiply(ship_right_vector, distance));
}
#endif /* DEBUG_MODE */
static void idle()
{
if (ship_speed != 0) {
ship_advance(ship_speed);
}
glutPostRedisplay();
#ifdef DEBUG_MODE
fprintf(stderr, "Speed: %.2f, X: %.2f, Y: %.2f, Z: %.2f\n",
ship_speed, ship_position.x, ship_position.y, ship_position.z);
#endif /* DEBUG_MODE */
}
static void draw_ship(void)
{
float rotation[16];
glTranslatef(ship_position.x, ship_position.y, ship_position.z);
rotation[0] = ship_right_vector.x;
rotation[1] = ship_right_vector.y;
rotation[2] = ship_right_vector.z;
rotation[3] = 0;
rotation[4] = ship_up_vector.x;
rotation[5] = ship_up_vector.y;
rotation[6] = ship_up_vector.z;
rotation[7] = 0;
rotation[8] = ship_forward_vector.x;
rotation[9] = ship_forward_vector.y;
rotation[10] = ship_forward_vector.z;
rotation[11] = 0;
rotation[12] = 0;
rotation[13] = 0;
rotation[14] = 0;
rotation[15] = 1;
glMultMatrixf(rotation);
glScalef(0.5, 0.5, 0.5);
glColor3f(0.9, 0.9, 0.9);
glBegin(GL_LINE_LOOP);
glVertex3f(-1.0, -1.0, 0.0);
glVertex3f(1.0, -1.0, 0.0);
glVertex3f(1.0, 1.0, 0.0);
glVertex3f(-1.0, 1.0, 0.0);
glEnd();
glBegin(GL_LINE_LOOP);
glVertex3f(-1.0, -1.0, 0.0);
glVertex3f(1.0, -1.0, 0.0);
glVertex3f(0.0, 0.0, 4.0);
glEnd();
glBegin(GL_LINE_LOOP);
glVertex3f(1.0, -1.0, 0.0);
glVertex3f(1.0, 1.0, 0.0);
glVertex3f(0.0, 0.0, 4.0);
glEnd();
glBegin(GL_LINE_LOOP);
glVertex3f(1.0, 1.0, 0.0);
glVertex3f(-1.0, 1.0, 0.0);
glVertex3f(0.0, 0.0, 4.0);
glEnd();
glBegin(GL_LINE_LOOP);
glVertex3f(-1.0, 1.0, 0.0);
glVertex3f(-1.0, -1.0, 0.0);
glVertex3f(0.0, 0.0, 4.0);
glEnd();
}
#ifdef DEBUG_MODE
static void draw_axis_indicator(void)
{
/* Draw it at origin. */
GLfloat old_line_width;
glGetFloatv(GL_LINE_WIDTH, &old_line_width);
glLineWidth(3.0);
glBegin(GL_LINES);
/* Red X-Axis */
glColor3f(1, 0, 0);
glVertex3f(0, 0, 0);
glVertex3f(1, 0, 0);
/* Green Y-Axis */
glColor3f(0, 1, 0);
glVertex3f(0, 0, 0);
glVertex3f(0, 1, 0);
/* Blue Z-Axis */
glColor3f(0, 0, 1);
glVertex3f(0, 0, 0);
glVertex3f(0, 0, 1);
glEnd();
glLineWidth(old_line_width);
}
#endif /* DEBUG_MODE */
static int planet_distance_compare(const void *p1, const void *p2)
{
return ((planet_distance_t *)p1)->distance <
((planet_distance_t *)p2)->distance;
}
static void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
if (camera_mode == 0) {
/* Inside ship. */
vector_t view_point;
view_point = vector_sum(ship_position, ship_forward_vector);
gluLookAt(ship_position.x, ship_position.y, ship_position.z,
view_point.x, view_point.y, view_point.z,
ship_up_vector.x, ship_up_vector.y, ship_up_vector.z);
} else {
/* Outside ship, a static look towards origin. */
glRotatef(45.0, 1.0, 0.0, 0.0);
glRotatef(120.0, 0.0, 1.0, 0.0);
glTranslatef(WORLD_SIZE / 2, 0 - (WORLD_SIZE / 2), WORLD_SIZE / 2);
}
/* Draw floor/roof/walls, which are actually big cubes! */
glColor3f(0.0, 0.0, 0.0);
glPushMatrix();
glTranslatef(0.0, -WORLD_SIZE, 0.0);
glScalef(WORLD_SIZE * 2, 0.1, WORLD_SIZE * 2);
#ifdef DEBUG_MODE
glColor3f(0.0, 0.5, 0.0);
#endif /* DEBUG_MODE */
glutSolidCube(1.0);
glPopMatrix();
glPushMatrix();
glTranslatef(0.0, WORLD_SIZE, 0.0);
glScalef(WORLD_SIZE * 2, 0.1, WORLD_SIZE * 2);
#ifdef DEBUG_MODE
glColor3f(0.0, 0.0, 0.5);
#endif /* DEBUG_MODE */
glutSolidCube(1.0);
glPopMatrix();
glPushMatrix();
glTranslatef(WORLD_SIZE, 0.0, 0.0);
glScalef(0.1, WORLD_SIZE * 2, WORLD_SIZE * 2);
#ifdef DEBUG_MODE
glColor3f(0.5, 0.0, 0.0);
#endif /* DEBUG_MODE */
glutSolidCube(1.0);
glPopMatrix();
glPushMatrix();
glTranslatef(-WORLD_SIZE, 0.0, 0.0);
glScalef(0.1, WORLD_SIZE * 2, WORLD_SIZE * 2);
#ifdef DEBUG_MODE
glColor3f(0.5, 0.5, 0.0);
#endif /* DEBUG_MODE */
glutSolidCube(1.0);
glPopMatrix();
glPushMatrix();
glTranslatef(0.0, 0.0, WORLD_SIZE);
glScalef(WORLD_SIZE * 2, WORLD_SIZE * 2, 0.1);
#ifdef DEBUG_MODE
glColor3f(0.5, 0.0, 0.5);
#endif /* DEBUG_MODE */
glutSolidCube(1.0);
glPopMatrix();
glPushMatrix();
glTranslatef(0.0, 0.0, -WORLD_SIZE);
glScalef(WORLD_SIZE * 2, WORLD_SIZE * 2, 0.1);
#ifdef DEBUG_MODE
glColor3f(0.0, 0.5, 0.5);
#endif /* DEBUG_MODE */
glutSolidCube(1.0);
glPopMatrix();
/* Calculate distance from ship to planets, because they need to be
drawn/rendered from the furthest away first. */
planet_distance_t distance[PLANETS_MAX];
for (int i = 0; i < planets_count; i++) {
distance[i].planet_index = i;
distance[i].distance = vector_distance(ship_position, planets[i].pos);
}
qsort(distance, planets_count, sizeof(planet_distance_t),
planet_distance_compare);
/* Draw planets. */
for (int i = 0; i < planets_count; i++) {
int n = distance[i].planet_index;
glPushMatrix();
GLUquadric *quadric = gluNewQuadric();
if (quadric != 0) {
glTranslatef(planets[n].pos.x, planets[n].pos.y, planets[n].pos.z);
glColor3f(planets[n].color_r, planets[n].color_g, planets[n].color_b);
gluSphere(quadric, planets[n].size, 20, 20);
gluDeleteQuadric(quadric);
}
glPopMatrix();
}
if (camera_mode != 0) {
glPushMatrix();
draw_ship();
glPopMatrix();
}
#ifdef DEBUG_MODE
glPushMatrix();
draw_axis_indicator();
glPopMatrix();
#endif /* DEBUG_MODE */
glFlush();
glutSwapBuffers();
}
static void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-1.0, 1.0, -1.0, 1.0, 1.5, 150.0);
glMatrixMode(GL_MODELVIEW);
}
static void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 's':
ship_pitch(-1.0);
break;
case 'w':
ship_pitch(1.0);
break;
case 'd':
ship_yaw(-1.0);
break;
case 'a':
ship_yaw(1.0);
break;
case 'z':
ship_roll(-1.0);
break;
case 'c':
ship_roll(1.0);
break;
case 'r':
ship_speed += 0.01;
break;
case 'f':
ship_speed -= 0.01;
break;
#ifdef DEBUG_MODE
case 't':
ship_advance(0.1);
break;
case 'g':
ship_advance(-0.1);
break;
case 'y':
ship_ascend(0.1);
break;
case 'h':
ship_ascend(-0.1);
break;
case 'u':
ship_strafe(0.1);
break;
case 'j':
ship_strafe(-0.1);
break;
case 'x':
camera_mode = (camera_mode) ? 0 : 1;
break;
#endif /* DEBUG_MODE */
case 'q':
exit(0);
break;
}
}
static void motion(int x, int y)
{
if (x > old_mouse_x) {
ship_yaw(1.0);
} else if (x < old_mouse_x) {
ship_yaw(-1.0);
}
if (y > old_mouse_y) {
ship_pitch(-1.0);
} else if (y < old_mouse_y) {
ship_pitch(1.0);
}
old_mouse_x = x;
old_mouse_y = y;
}
void generate_planets(void)
{
for (int x = GRID_START; x < GRID_END; x += GRID_SPACING) {
for (int y = GRID_START; y < GRID_END; y += GRID_SPACING) {
for (int z = GRID_START; z < GRID_END; z += GRID_SPACING) {
if (x == 0 && y == 0 && z == 0) {
/* Ignore origin. */
continue;
}
if ((rand() % PLANETS_CHANCE) == 0) {
planets[planets_count].pos.x = (x - 2) + (rand() % 4);
planets[planets_count].pos.y = (y - 2) + (rand() % 4);
planets[planets_count].pos.z = (z - 2) + (rand() % 4);
planets[planets_count].size =
((rand() % ((GRID_SPACING * 10) - 1)) / 20.0) + 0.1;
planets[planets_count].color_r = (rand() % 11) / 10.0;
planets[planets_count].color_g = (rand() % 11) / 10.0;
planets[planets_count].color_b = (rand() % 11) / 10.0;
#ifdef DEBUG_MODE
printf("X=%.1f, Y=%.1f, Z=%.1f, Size=%.1f, Col=%.1f;%.1f;%.1f\n",
planets[planets_count].pos.x,
planets[planets_count].pos.y,
planets[planets_count].pos.z,
planets[planets_count].size,
planets[planets_count].color_r,
planets[planets_count].color_g,
planets[planets_count].color_b);
#endif /* DEBUG_MODE */
if ((planets_count + 1) >= PLANETS_MAX) {
return;
} else {
planets_count++;
}
}
}
}
}
}
int main(int argc, char *argv[])
{
srand(time(NULL));
generate_planets();
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(800, 800);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
glClearColor(0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutIdleFunc(idle);
glutKeyboardFunc(keyboard);
glutMotionFunc(motion);
glutMainLoop();
return 0;
}
Here is a screenshot of what it looks like, just some "planets" that looks like spheres:
Turning Frog VL6180 Upgrade
Many years ago I got a soldering kit, the "ELENCO 21-882" which is a "frog robot" with two motors that reacts to sound. I had been thinking about ways to upgrade it, and I finally got around to doing that by controlling it with a Arduino Pro Mini and a VL6180 sensor to measure distance.
The original sound based control works by clocking a "4017 Decade Counter" IC with the input from a electret microphone. The easiest way to hijack the control is to remove this IC from the socket and wire the Arduino into it.
I used the following connections:
Arduino RAW <-> Socket pin 16 (VDD, 9V supply from battery.)
Arduino GND <-> Socket pin 8 (VSS)
Arduino D10 <-> Socket pin 1 (Output, diode for left motor.)
Arduino D11 <-> Socket pin 7 (Output, diode for right motor.)
Arduino D12 <-> Socket pin 2 (Output, diodes for both motors.)
Cobbled together it looks like this:
The FTDI is only used for uploading the program and can be removed of course.
The Arduino Sketch code is very simple:
#include "Adafruit_VL6180X.h"
static Adafruit_VL6180X vl = Adafruit_VL6180X();
static int keep_going = 0;
void setup() {
pinMode(10, OUTPUT); // Left motor
pinMode(11, OUTPUT); // Right motor
pinMode(12, OUTPUT); // Both motors
pinMode(13, OUTPUT); // On-board Arduino LED
vl.begin();
}
void loop() {
uint8_t range = vl.readRange();
uint8_t status = vl.readRangeStatus();
if ((status == VL6180X_ERROR_NONE) && (range < 200)) {
// Go left
digitalWrite(12, LOW);
digitalWrite(10, HIGH);
keep_going = 10; // Keep going to finish the turn...
} else {
if (keep_going > 0) {
keep_going--;
} else {
// Go forward
digitalWrite(10, LOW);
digitalWrite(12, HIGH);
}
}
delay(50);
}
USB IR REMOCON Firmware Replacement
I bought this Bit Trade One USB Infrared Remote Control Kit at an electronics store in Japan, which lets you use a standard TV remote to control a PC. While the device works on Linux, since it presents itself as a standard USB HID device, it can only be configured in Windows. But a bigger problem is that the original firmware contained some kind of bug where part of the TV remote mappings would get corrupted after power cycling.
To get around these limitations and problems I have created a new firmware replacement for the onboard PIC18F14K50 microcontroller. For maximum flexibility I decided to make something that emulates the protocol used by the Dangerous Prototypes USB IR Toy. This means the device can be used together with LIRC on Linux, which offers a lot of advanced functionality. This also moves the configuration aspect to software on Linux instead of needing to re-flash the PIC microcontroller EEPROM. Note that this device also has an IR sender, but I only implemented support for the IR receive part.
You can get the firmware here or the MPLAB project source code here. I have used Microchip's own USB stack for this project, which is licensed under the Apache license. The parts I wrote myself I consider to be released unlicensed directly into the public domain. I'm including the main part of the code here for an easy reference:
#include "system.h"
#include <stdint.h>
#include <string.h>
#include <stddef.h>
#include "usb.h"
#include "app_irtoy_emu.h"
#include "usb_config.h"
static uint8_t readBuffer[CDC_DATA_OUT_EP_SIZE];
static uint8_t writeBuffer[CDC_DATA_IN_EP_SIZE];
static bool inSamplingMode = false;
static uint16_t pulseHighLen = 0;
static uint16_t pulseLowLen = 0;
static uint16_t pendingPulse = 0;
static bool endOfTransmission = true;
static bool waitForEOT = false;
void samplingModeSetup(void)
{
/* Set variables to known state. */
pulseHighLen = 0;
pulseLowLen = 0;
pendingPulse = 0;
endOfTransmission = true;
waitForEOT = false;
T0CON = 0b11000000; /* Enable Timer0 as 8-Bit with no scaling. */
RCONbits.IPEN = 1; /* Enable priority levels on interrupts. */
INTCON2bits.TMR0IP = 1; /* Make Timer0 a high priority interrupt. */
INTCONbits.TMR0IF = 0; /* Clear Timer0 interrupt flag. */
INTCONbits.TMR0IE = 1; /* Enable Timer0 interrupts. */
INTCONbits.GIEH = 1; /* Make sure high priority interrupts are enabled. */
INTCONbits.GIEL = 1; /* Make sure low priority interrupts are enabled. */
}
void samplingModeService(void)
{
uint8_t numBytesRead;
numBytesRead = getsUSBUSART(readBuffer, 1);
if (numBytesRead == 1 && readBuffer[0] == 0x00) /* Reset */
{
/* Disable Timer0 interrupts. */
INTCONbits.TMR0IE = 0;
inSamplingMode = false;
return;
}
INTCONbits.TMR0IE = 0;
if (pendingPulse > 5)
{
writeBuffer[0] = (uint8_t)(pendingPulse / 256);
writeBuffer[1] = (uint8_t)(pendingPulse % 256);
putUSBUSART(writeBuffer, 2);
pendingPulse = 0;
endOfTransmission = false;
waitForEOT = true;
}
if ((waitForEOT == true) && (endOfTransmission == true))
{
writeBuffer[0] = 0xFF;
writeBuffer[1] = 0xFF;
putUSBUSART(writeBuffer, 2);
waitForEOT = false;
}
INTCONbits.TMR0IE = 1;
}
void APP_IRToyEmulationInterrupt(void)
{
if (INTCONbits.TMR0IF == 1)
{
/* Check if IR sensor (inverted input) is active. */
if (PORTCbits.RC7 == 0)
{
if (pulseLowLen > 5)
{
pendingPulse = pulseLowLen;
}
pulseLowLen = 0;
pulseHighLen += 2;
}
else
{
if (pulseHighLen > 5)
{
pendingPulse = pulseHighLen;
endOfTransmission = false;
}
pulseHighLen = 0;
if (endOfTransmission == false)
{
pulseLowLen += 2;
if (pulseLowLen >= 0xFFFE)
{
pulseLowLen = 0;
endOfTransmission = true;
}
}
}
INTCONbits.TMR0IF = 0;
}
}
void APP_IRToyEmulationInitialize()
{
line_coding.bCharFormat = 0;
line_coding.bDataBits = 8;
line_coding.bParityType = 0;
line_coding.dwDTERate = 115200;
/* I/O settings as used in orignal Bit Trade One firmware. */
TRISB = 0x00;
TRISC = 0x80;
LATC = 0xFF;
ANSEL = 0x00;
ANSELH = 0x00;
/* But turn off IR sender diode output, no support implemented. */
PORTCbits.RC5 = 0;
}
void APP_IRToyEmulationTasks()
{
/* If the USB device isn't configured yet, we can't really do anything
* else since we don't have a host to talk to. So jump back to the
* top of the while loop. */
if (USBGetDeviceState() < CONFIGURED_STATE)
{
return;
}
/* If we are currently suspended, then we need to see if we need to
* issue a remote wakeup. In either case, we shouldn't process any
* keyboard commands since we aren't currently communicating to the host
* thus just continue back to the start of the while loop. */
if (USBIsDeviceSuspended() == true)
{
return;
}
if (inSamplingMode == true)
{
samplingModeService();
}
else
{
if (USBUSARTIsTxTrfReady() == true)
{
uint8_t numBytesRead;
numBytesRead = getsUSBUSART(readBuffer, 1);
if (numBytesRead == 1)
{
switch (readBuffer[0])
{
case 'S': /* IRIO Sampling Mode */
case 's':
writeBuffer[0] = 'S'; /* Answer OK */
writeBuffer[1] = '0';
writeBuffer[2] = '1';
putUSBUSART(writeBuffer, 3);
samplingModeSetup();
inSamplingMode = true;
break;
case 'V': /* Acquire Version */
case 'v':
writeBuffer[0] = 'V'; /* Answer OK */
writeBuffer[1] = '9'; /* Hardware Version */
writeBuffer[2] = '9'; /* Firmware Version High */
writeBuffer[3] = '9'; /* Firmware Version Low */
putUSBUSART(writeBuffer, 4);
break;
default: /* All the rest is unsupported! */
writeBuffer[0] = '?';
putUSBUSART(writeBuffer, 1);
break;
}
}
}
}
#if defined(USB_POLLING)
USBDeviceTasks();
#endif
CDCTxService();
}
To use it in LIRC, setup lirc_options.conf similar to the IR Toy using:
driver = irtoy
device = /dev/ttyACM0
USB Relay Control Simplified
I got a USB controlled relay board a while ago, which is identified with the USB ID 16c0:05df. There are various controller programs for these on GitHub, but all of them are rather complicated, so I decided to write my own simplified version using the same principles. Like others, it has a dependency against the hidapi library.
The result is this C program:
#include <hidapi/hidapi.h>
#include <wchar.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define TARGET_DEVICE L"USBRelay2"
#define RELAY_OFF 0xfd
#define RELAY_ON 0xff
int main(int argc, char *argv[])
{
struct hid_device_info *hidinfo;
hid_device *hiddev;
unsigned char buf[8];
int result, relay_number, relay_operation;
hidinfo = hid_enumerate(0, 0);
while (hidinfo != NULL) {
if (0 == wcscmp(hidinfo->product_string, TARGET_DEVICE)) {
break;
}
hidinfo = hidinfo->next;
}
if (hidinfo == NULL) {
fprintf(stderr, "Did not find '%ls' in USB devices!\n", TARGET_DEVICE);
return 1;
}
hiddev = hid_open_path(hidinfo->path);
if (hiddev == NULL) {
fprintf(stderr, "hid_open_path() failed on: %s\n", hidinfo->path);
return 1;
}
if (argc > 2) {
relay_number = atoi(argv[1]) & 0b11; /* Limit to 2 relays. */
relay_operation = 0;
if (0 == strcasecmp(argv[2], "on")) {
relay_operation = RELAY_ON;
} else if (0 == strcasecmp(argv[2], "off")) {
relay_operation = RELAY_OFF;
} else {
fprintf(stderr, "Invalid relay operation\n");
hid_close(hiddev);
return 1;
}
memset(buf, 0x00, sizeof(buf));
buf[0] = 0x00;
buf[1] = relay_operation;
buf[2] = relay_number;
result = hid_write(hiddev, buf, sizeof(buf));
if (result == -1) {
fprintf(stderr, "hid_write() failed!\n");
hid_close(hiddev);
return 1;
}
}
buf[0] = 0x01;
result = hid_get_feature_report(hiddev, buf, sizeof(buf));
if (result == -1) {
fprintf(stderr, "hid_get_feature_report() failed!\n");
hid_close(hiddev);
return 1;
}
printf("Relay #1: %d\n", buf[7] & 0b01);
printf("Relay #2: %d\n", (buf[7] & 0b10) >> 1);
printf("Usage: %s <relay number> <on|off>\n", argv[0]);
hid_close(hiddev);
return 0;
}
Compile it like so: gcc -o usbrelay2 usbrelay2.c -lhidapi-hidraw