Articles tagged “Electronics”

This is an extremely belated followup to a post from November last year, though one of the reasons for the delay was repeatedly being sent the wrong electronic components which ultimately led to the post from December. I'll try to explain as best I can... Towards the end of last year I bought myself a SmartBox, a computer control system that's based around a 65C02 CPU and that runs programs written in an interpreted BASIC-like programming language, with software uploaded via a computer's serial connection (and once the programs are loaded onto the box, the serial connection can be severed and the program will continue to run).

Electronics SmartBox

This is a quick post about problems I'd been having loading tape cassette recordings from my PC to a Sharp PC-1500 Pocket Computer along with a potential solution for anyone having similar issues. Sharp PC-1500 Pocket Computer connected to the CE-150 Printer and Cassette Interface The Sharp PC-1500 is a small computer from the early 1980s that can run programs primarily written in BASIC. Programs can be saved to and loaded back from cassette tape but to do this requires it to be connected to the CE-150, a cassette interface that also includes a four-colour plotter.

Electronics PC-1500 Sharp Pocket Computer Tape loader

I've been having a tricky time buying LM35DZ analogue temperature sensors for a project recently. One pair of probes and a bag of loose components labelled LM35DZ turned out to be regular NPN transistors with a fake label on them, and another pair of probes ended up being DS18B20 digital temperature sensors. Whilst the DS18B20 temperature sensors were useless for the project I had in mind they were still functioning components. These use the 1-Wire serial bus, a bus named for the way that its single data line can also be used to parasitically power the devices on the bus.

1-Wire BBC BASIC Electronics Z80 Z88

My latest eBay purchase was influenced by a desire for some practical test/prototype equipment, a bit of nostalgia and a desire to learn something new. A lot of my projects involve some sort of microcontroller running some software that will take inputs, perform decisions on them, and produce outputs. Getting to that stage tends to involve quite a lot of "boilerplate" hardware and software setup, and I'd quite like something that I can just plug in and get cracking with and write some quick test code instead of having to assemble a circuit on a breadboard or faff around with a clumsy IDE.

6502 Arculator C# Electronics RISC OS SmartBox SmartMove

It's been quite a while since I posted about my Z80 Computer project. This is a home-made Z80 computer I built back in 2010 that features a 10MHz Z80 CPU with 64KB RAM that runs CP/M 3. It can drive an internal LCD, TV or VGA monitor at 320x240 (monochrome only) and unfortunately is a project I was never too happy with due to several compromises I had to make in its design – though at the time I was happy enough I got it to work at all! The video output was limited by both my choice to use an internal graphical LCD and the limitations of the dsPIC33F I chose to use to drive it and the software was all a bit half-baked.

CP/M Electronics Z80 Z80 computer

When reading about the Cambridge Z88 computer and its available software I bumped into the occasional mention of Z-Tape by Wordmongers, a system that allowed you to back up files from your Z88 to a cassette recorder. I had wondered how this worked, assuming there some sort of external hardware to connect the cassette recorder to the Z88 (likely via its serial port). I'd done some work on tape loading and saving myself for the Sega Master System and had come up with a somewhat hacky but minimal solution that relies on abuse of a hex inverter.

Electronics Tape loader Z88

The VDrive is a handy module for electronic projects that need to access files on a USB flash drive. It's based around a USB host microcontroller and comes preinstalled with some firmware that provides control over the drive with simple commands sent via a serial connection (UART or SPI). A few years ago I started putting together some code to connect the module to my Cambridge Z88 computer. All I needed was a way to power the drive and a MAX232 chip to translate the computer's RS-232 interface to the VDrive's logic levels, and after around 150 lines of BBC BASIC I had a program that could show directory listings, let me browse folders, and fetch files from the USB drive to the Z88's file system.

Electronics USB VDrive Z80 Z88

One of the issues holding me back with my development of the Light Gun Commando project (aside from a lack of free time due to the day job) was running out of prototyping breadboards and the difficulty of swapping between different console adaptor boards for testing. Normally by this point I'd have started soldering together more permanent prototypes on little circuit boards, but I've been having a difficult time with the boards I've got in stock apparently being made of a metal that's impossible to solder to.

Electronics RetroWiFiModem TI-83+ TIWiFiModem Z80

After building a USB Guncon 2 adaptor for my Light Gun Commando project the Xbox seemed like it should be the next console to support as that also uses USB for its controllers. The xboxdevwiki seemed like a good starting point for information about its controller protocol. I wanted to be able to compare against real Xbox controllers too, so I bought an Xbox controller cable online and cut it in half so I could use the plug end to connect my circuit to the Xbox and the socket end to connect Xbox controllers to my PC.

Electronics Light Gun Commando Light guns Xbox

Some light gun games, such as Resident Evil: Dead Aim, require the use of more conventional controller inputs along with pointing a gun at the screen and pulling a trigger. Some light guns have a d-pad in an easily accessible location on the back of the controller to allow for reasonably comfortable control of your character with a thumb, but the Wii remote's placement of the d-pad on the top and near the front makes it fairly awkward to use when held like a gun. Fortunately, there is an extension controller port on the bottom of the Wii remote that allows the connection of additional controllers such as the Nunchuck or Classic Controller that can be held separately from the gun or clipped onto the Wii remote's gun-shaped holder to bring the controls into a more easily-accessible location.

Classic Controller Electronics Light Gun Commando Light guns Nunchuck uDraw GameTablet Wii remote

I've continued working on the Light Gun Commando project that I hope to be able to use as a system for playing light gun games on old consoles with Wii remotes. The Wii remotes are connected to an ESP32 microcontroller using Bluetooth, and I had a few small issues with this arrangement, most obviously with a cheap third-party Wii remote that refused to pair. I had also encountered a few other quirks and oddities along the way, such as the timer capture's interrupt (used to measure the horizontal scanline period for timing purposes) crashing the whole system if it received too many pulses in a short while (e.g.

Electronics Guncon 2 Light Gun Commando Light guns Namco Sega Sega Dreamcast Sony Sony PlayStation 2

As the previous entries on this site might indicate, I do enjoy a good light gun game. Unfortunately, when it comes to playing them on home consoles you usually need to use a CRT television for the gun controllers to work. I have a CRT or two at my disposal but I'm well aware they won't last forever and they're not really the most convenient devices even when they are working at their best. Bearing this in mind I decided to try to find a way to get light guns working on LCD TVs. My experiments back in early 2015 – called DC-LiGuE, the "Dreamcast Light Gun Emulator" – never amounted to much.

Electronics Light Gun Commando Light guns Sega Sega Dreamcast Sega Mega Drive Sega Mega-CD Sega Saturn Sony PlayStation

I recently built some Dreamcast Race Controller "De-Dead Zone" mods for people and before popping them in the post I tested them in my wheel. During this process I noticed an unpopulated region of the main PCB:
I remember reading that some versions of the Race Controller had a socket on the back for the connection of a set of pedals, however those pedals were never released and games instead rely on a pair of analogue paddles mounted behind the wheel for braking and acceleration. I wondered if the pedal functionality was still available on my wheel, even though it lacks the relevant socket on the back.

Electronics Race Controller Sega Sega Dreamcast

More musing on tape phases I bought a few more Acorn-format BBC BASIC cassettes to test my adaptation of BBC BASIC to the Sega Master System with, and have found a few interesting oddities since my last post. In that post I made the assertion that the phase of the recorded signals on the tapes is at 180°, i.e. each wave cycle goes negative before it goes positive (whereas a 0° phase would go positive before it goes negative). This matched the documentation I'd read, the output of tools like PlayUEF and my own tests with commercially-recorded tapes.

BBC BASIC Electronics Sega Sega Master System Tape loader Z80

I have now moved the tape interface circuit described in the previous entry from its breadboard prototype to a neat enclosure where I am happy to report it mostly works as well as it did before. I have spotted two issues, though. The first affects my small cassette recorder but not the large one, and is related to reading files from tape via the file IO routines (such as OPENIN then BGET# to retrieve a single byte, not from LOAD). Files are stored on tape in 256 byte blocks, and when the file is opened a whole 256 byte block is read from the tape and copied to the Master System's RAM.

BBC BASIC Electronics Sega Sega Master System Tape loader USB VDrive Z80

It's been quite a while since my last post but work has continued with the version of BBC BASIC (Z80) for the Sega Master System. Most of the features I have been working have not been particularly exciting to write about on their own, but here are some of the notable changes:
All VDU code (for text and graphics output) has been moved to a separate ROM bank, freeing up around 16KB of extra ROM space. It makes calling the code slightly more complicated but in the previous post I mentioned that I had less than 100 bytes of free ROM space so this was definitely required.

BBC BASIC Electronics Sega Sega Master System Tape loader Z80

I have continued to work on the Sega Master System version of BBC BASIC, and it's feeling much more like a practical version of BASIC than something that was just holding together to run one specific program! One of the key improvements is to standardise the handling of the different graphics modes. Previously I was using a coordinate system where (0,0) is in the top left corner and all drawing operations were carried out using physical device coordinates (so the screen was treated as being 256 pixels wide and 192 pixels tall).

BBC BASIC Cogwheel Electronics Emulation Sega Sega Master System Z80

I've recently been spending some time finding a way to run BBC BASIC on the Sega Master System, inspired by BASIC Month 6: The Mandelbaum Set on the RetroBattlestations Reddit community. When this month's program was first announced I tried running it on my only unarguably retrobattlestation, my Cambridge Z88, but the screen's low (vertical) resolution didn't do the program much justice. I thought this gave me two options:
Control some external piece of retro tech to produce higher-resolution output (e.g.

BBC BASIC Electronics Sega Sega Master System Z80

I love an unusual accessory for a video game console or computer, and one such accessory is the Dreamcast MIDI Interface Cable, HKT-9200, which allows you to connect MIDI devices to the Dreamcast console's serial port. Only released in Japan and with only one piece of software released for it — the O･to･i･re (お･と･い･れ) sequencer – these are a somewhat hard to find accessory nowadays and prices for second-hand units are far beyond what I could hope to afford (at the time of writing there are two on eBay, both for over £300).

Electronics MIDI Music Sega Sega Dreamcast

Since my previous post I've had a chance to test the Sega Light Phaser to Konami Justifier adaptor circuit with Lethal Enforcers II: Gun Fighters and it seems to work well throughout the game so I thought it was a good time to put the project into a neat box. The Mega Drive uses common DE-9 connectors for its controller ports. You can easily find metal connectors with lugs for panel mounting however I wanted to use plastic connectors similar to the ones on the original console – not just for a consistent look, but to also protect the plastic connectors on the Sega Light Phasers from being scratched by the sharp edges of metal connectors.

Electronics Konami Justifier Light guns Mega Drive light gun adaptor Sega Sega Light Phaser Sega Master System Sega Mega Drive

Here's a quick update to the two Mega Drive light gun adaptor circuits, all to a few extra resistors in and around the adaptor and the console. The real Sega Menacer receiver drives the TH line (used to indicate when the gun has seen light) directly from the output of a NOR gate with a 470Ω resistor in series. My circuit uses a transistor in the open-collector configuration with a 10KΩ resistor on the base input and a 1KΩ pull-up resistor, which is the same as the circuit used in the original Sega Light Phaser.

Electronics Konami Justifier Light guns Mega Drive light gun adaptor Sega Sega Light Phaser Sega Master System Sega Mega Drive Sega Menacer

In the previous post I mentioned I was dissatisfied with the optimisation of the Light Phaser to Justifier adaptor circuit. This was because I was using two quad two-input multiplexer chips (eight multiplexers total) but only using three multiplexers on each chip but also needed two inverter gates and so had to add a third chip to accommodate that requirement. It seemed like there must be a better solution, and after pondering this in the shower I think I found it. One of the inverters is required for the transistor used to drive the TH line from the circuit.

Electronics Konami Justifier Light guns Mega Drive light gun adaptor Sega Sega Light Phaser Sega Master System Sega Mega Drive

Following my adventures with building an adaptor that lets me use Sega Light Phaser guns in Sega Menacer games it seemed sensible to turn my attention to the other type of light gun for the Sega Mega Drive – the Konami Justifier. The two Justifier guns in a photo from Wikipedia These guns are unsurprisingly incompatible with the Sega Menacer and Sega Light Phaser and supported in even fewer games on the stock Mega Drive (only Lethal Enforcers and Lethal Enforcers II: Gun Fighters). However, these games are more in line with the type of light gun game that I like to play than what you'd find in the Menacer's library (even though the digitised sprites haven't aged particularly gracefully) and the guns are eye-wateringly expensive if you want to get a set of both for two-player games which makes the idea of a cheap adaptor to use the Master System's Light Phaser more appealing.

Electronics Konami Justifier Light guns Mega Drive light gun adaptor Sega Sega Light Phaser Sega Master System Sega Mega Drive

In the last post I was having difficulty with the overall logic for handling the light sensor signal from the Sega Light Phaser and passing that along to the Mega Drive as if it was coming from the Menacer receiver. This involves latching the signal (instead of passing it along directly) and allowing the console to reset it once handled via the TR line. The signal needs to be delayed as well to simulate the delay from the overhead of the Menacer's wireless communications; without this delay the aiming is offset to the left.

Electronics Light guns Mega Drive light gun adaptor Sega Sega Light Phaser Sega Master System Sega Mega Drive Sega Menacer

Since the last post about my experiments with using a Sega Light Phaser to play Mega Drive games I've had some good results and some disappointing ones that I'm still trying to work through. The easy problem to solve was the handling of the buttons and making sure that the gun continued to be detected as a Menacer whenever a button was pressed. The previous circuit used active-high buttons (including an inverter to convert the active-low trigger from the Light Phaser into active-high signal) gated using the console's TH line via an AND gate.

Electronics Light guns Mega Drive light gun adaptor Sega Sega Light Phaser Sega Master System Sega Mega Drive Sega Menacer

I'm a big fan of light gun games and have guns and games for most of the Sega systems – the Master System's Light Phaser, the Saturn's Virtua Gun and the Dreamcast's gun all get plenty of use. One notable omission is the Sega Mega Drive and its Menacer light gun. This is a wireless gun with a range of bulky plastic accoutrements that represented Sega's efforts in the 16-bit generation; unfortunately only three games were released for it on the Mega Drive – a six-in-one collection of minigames that came bundled with the gun, a port of T2: The Arcade Game and the ferociously-expensive Body Count.

Electronics Light guns Mega Drive light gun adaptor Sega Sega Light Phaser Sega Master System Sega Mega Drive Sega Menacer

I have a ToToTEK GG-PRO flash cartridge to run homebrew software on my Game Gear however I have never been able to get it to work on my current PC and it seems that it's hard to find a Master System equivalent these days. A contemporary alternative is the Master EverDrive and it is by all accounts an excellent piece of equipment however it is a very expensive product. I had, however, heard that certain Master System cartridges could be modified to accommodate a flash memory chip in place of their stock mask ROM.

Electronics Sega Sega Master System

A few years ago I posted about a way to get the Willem chip programmer to work with modern PCI parallel ports via a DLL that remapped the legacy port addresses to the ones of your modern card (in my case my card is installed at 0xCCD8 instead of 0x378). Since its release I've had several people contact me asking for advice and support, including a few questions about 64-bit support. Until recently I had been using a 32-bit OS and as such hadn't run into compatibility issues myself. I had replaced the DLL in the zip archive for the project with an allegedly 64-bit-compatible version of the inpout32.dll library that the is used to access the I/O ports but I was unable to test this myself, however it still worked in a 32-bit OS so hoped that it would also work on a 64-bit OS as claimed.

Electronics Remapped IO.DLL Willem

I bought my Sega Master System-compatible 3D glasses almost exactly ten years ago for use in my LCD Shutter Glasses Adaptor project. More recently I've acquired a CRT television and an actual Sega Master System so I could in theory make use of the glasses as I had originally intended - with Sega Master System games. I've been keeping an eye on eBay for the 3D Glasses Adaptor for the Master System. This is a device that plugs into the console's card slot and allows it to drive the glasses with the software controlling which LCD shutter is open and which is closed by writing to the card.

Electronics LCD shutter glasses adaptor Sega Sega Master System Stereoscopy

I recently bought myself a Race Controller wheel for the Sega Dreamcast and was a little disappointed with the way that it performed. I had read reviews online before buying it and some did mention that it didn't handle particularly well but others did mention that it was about the best controller available for the system so I didn't feel it was too risky a purchase. The issues I have with the wheel stem from its excessively large dead zone – you need to turn the wheel quite far before your car starts to turn, making it feel sluggish and unresponsive.

Dreamcast Electronics Race Controller Repairs Sega

I recently purchased an inexpensive PlayStation controller USB adaptor for my PC. Several reviews confirmed that it was compatible with the controller's analogue joysticks so I thought it would be what I was after. Life is rarely that easy with cheap electronics, unfortunately! When it arrived I plugged it in and Windows installed the appropriate HID drivers for it automatically, but as much as I waggled the joysticks on a connected DualShock 2 controller the axis preview in Control Panel remained resolutely in the zero position.

Comments Electronics PlayStation Repairs

I've been tinkering with a number of small projects recently. I've resumed work on an LED clock for my bedroom (using a 32×8 LED display) and written an experimental BASIC interpreter in C# which I may try to turn into an assembler (implementing assembly statements as BASIC ones). In the mean time, I have finished one project — a device to display a calculator's screen on a television set. Texas Instruments also manufacture a product that allows you to view the screen contents of a calculator with supported hardware on a TV; here is a video demonstrating it.

Comments ATmega168 AVR Electronics NTSC PAL TI-83+ TV TV Demonstrator

The ultimate goal for the video display controller module I have been working on is to drive the display in my Z80 computer project. As I have now got a pretty good set of features I thought it would be a good idea to join the two projects together. The big board in the lower middle of the above photograph is the main body of the computer, including the Z80, its RAM, the ATmega644P that is used to handle I/O, an SD card for storage and a DS1307 real-time clock. The small board in the bottom left of the photo is the power supply (supplying both 5V and 3.3V) and clock generator (providing a 20MHz and 10MHz clock).

Comments dsPIC33 VDC dsPIC33FJ128GP802 Electronics PIC Z80 Z80 computer

I have spent quite a while working on different projects that generate PAL video signals in software. This may seem a bit odd if you consider the fact that I don't own a TV, so tend to rely on a video capture card or VGA box to see the output of these projects on a computer monitor — something I do have a fair number of. This reliance on another piece of technology between my project and the display device is not something I'm too keen on, so have spent some time adding native 640×480 60Hz VGA output to my dsPIC33 video display controller.

Comments dsPIC33 VDC dsPIC33FJ128GP802 Electronics PIC VGA

The dsPIC33 video display controller project I am working on needs to support several common text output and drawing operations offered by existing BBC BASIC implementations. The previous demo included basic point, line and circle outlining functions, but I also need to output text and outline (or fill) rectangles, circles, ellipses and triangles. On top of that the drawing operations need to support multiple colours and plotting modes. Owing to processing power and memory limitations the output is black and white only but different "shades" can be implemented with dither patterns.

Comments dsPIC33 VDC dsPIC33FJ128GP802 Electronics PAL PIC Spinning cube TV

As you may have guessed from the ratio of photos to actual content in my entries I do quite enjoy taking photos of things. One of the reasons I enjoy working with electronics over writing software for computers is that a finished product results in something physical, which I find much more rewarding than a purely virtual hobby. One type of photograph I particularly enjoy on other websites is the interactive 360° view of a product. The ability to click and drag to rotate an object on the screen makes it seem more real.

Comments C# Electronics JavaScript Lego Photography PICAXE PICAXE-08M

I have currently been using some terminal emulation software on my PC to see the output of the Z80 computer. It seems a little silly to rely on a large multi-gigahertz, multi-megabyte machine just to display the output from a machine at the megahertz and kilobyte end of the scale. I had previously done some work with a dsPIC33 to drive a 320×240 pixel graphical LCD so dug out its breadboard and dusted off the code to try to make something of it. Inspired by John Burton's recent experiments with PAL TV output I decided that the first thing I should do is add support for TV output.

Comments dsPIC33 VDC dsPIC33FJ128GP802 Electronics LCD PAL PG320240H-P9 PIC Spinning cube TV

Up to this point I have been running CP/M 2.2 on the Z80 computer. CP/M 3 adds a number of useful features, including the following:
Support for more than 64KB RAM via banked memory. Standardised access to real-time clock for file date and time stamping.Improved text entry on the command-line when using the memory-banked version, such as the ability to move the cursor when editing and recall the previously entered line.Support for disks with physical sectors larger than the default record size of 128 bytes.

Comments ATmega644P AVR CP/M DS1307 Electronics SD card Z80 Z80 computer

The hardware for the computer has changed in (mostly) subtle ways since the last post, with the exception of a PS/2 socket for connection to a keyboard. PS/2 keyboards (which use the same protocol as the older AT keyboard) communicate with the host by clocking data in either direction (keyboard to host or host to keyboard) over two wires, appropriately named "clock" and "data". An AVR pin change interrupt is used to detect a change in state of the clock line and either input or output a bit on the data line depending on the current direction of data transmission.

Comments ATmega644P AVR CP/M Electronics Keyboard Z80 Z80 computer

I've been working on a new Z80 computer over the last few days. I would say that I had been working on the existing Z80 computer were it not for the fact that this a completely new design. The previous computer had two 32KB RAM chips to provide a total of 64KB RAM. To run a user program you need to get it into RAM somehow, so I also included a 128KB ROM chip which occupied the lower 16KB of the Z80's address space to provide the fixed operating system that could be used to load programs. By adding memory banking hardware I could select one of eight 16KB pages of ROM.

Comments ATmega644P AVR CP/M Electronics Z80 Z80 computer

I enjoy watching films and mainly do so sitting at my desktop PC. This has taught me that cheap office chairs are not the most comfortable things to sit on for extended periods of time, especially when the next room contains a comfortable bean bag and a good place to stick a screen. A gap between the two rooms allows me to pass cables from one to the other, and after purchasing a 10m DVI-D cable and a USB extension lead on eBay I had both picture and sound sorted out (I use a USB sound "card"). This left me with one final problem: how to control the PC through a wall.

Comments ATmega168 ATtiny84 AVR Electronics Remote control USB

I have recently been working on building my own Superprobe. This is a cheap and simple tool based around a single PIC 16F870, a four-digit display and a handful of other parts. Hardware details and software can be found on the Superprobe section of the Mondo Technology website. As the name suggests, at its simplest the Superprobe can be used as a logic probe, displaying an L, H or - if it touches a point in the circuit that is in a low, high or floating state. What makes it so "super" is that by using the two input buttons you can switch it to a different mode.

Comments 16F876A Electronics PIC

In a previous entry I mentioned that I had purchased a PG320240H-P9 graphical LCD. This is a 320×240 white-on-blue pixel display, and it does not have an on-board controller or RAM. To display something on it you need to constantly refresh it with picture data; in this instance, sending four pixels at a time, starting from the top left and working from left to right, top to bottom — a bit like the scanning pattern of a CRT monitor. Connecting a circuit to the LCD is made slightly more tricky by its use of a 16-pin 1mm flexible flat cable.

Comments dsPIC33 VDC dsPIC33FJ128GP802 Electronics LCD PG320240H-P9 PIC Spinning cube

In an attempt to solve the screen resolution problem issue I've bought a very cheap 320×240 pixel graphical LCD – a PG320240H-P9 on eBay for $24. Part of the reason for its cheapness may be down to its the lack of a controller; you need to constantly refresh the LCD with pixel data yourself (easier to use modules have integrated controllers that refresh the display for you from some on-board RAM). If I manage to get it working I'll have a 128×64 pixel graphical LCD going spare – finding a use for it could make an interesting project.

Comments ATmega644P AVR CHIP-8 Electronics

It's been some time since I worked on my Z80 computer project, but the recent electronics projects I've completed have got me thinking about it again. Click to watch the video on YouTube I did record a video to demonstrate the basic parts of the computer and some of its flaws a few months ago, which can be seen above. However, I'm now thinking of a more radical redesign than fixing the I/O board's shortcomings. One of the reasons for my lack of motivation is that even if I did get something working I wouldn't have much software to run on it; it would be a lot of work to write software that only ran on that one particular machine.

Comments CP/M Electronics Z80 Z80 Computer

Assembling a circuit on breadboard is a good way to experiment with electronics, but the result is not something you could really use – it's bulky, fragile and awkward to set up. It's far nicer to solder the components of the circuit together to form a more permanent device and put it in a enclosure to make it robust. This is not something I'm especially good at, but something I thought I'd try with the VGA line blanker and LCD shutter glasses controller I've been experimenting with recently. In the past I've struggled along with a hand drill and the nail file on a Swiss Army knife, but have more recently acquired a high-speed rotary tool and an assortment of attachments which make things much easier.

Comments Electronics LCD shutter glasses adaptor Stereoscopy

Some time ago, I posted about using interlaced video to display 3D images. Whilst the idea works very nicely in theory, it's quite tricky to get modern video cards to generate interlaced video at a variety of resolutions and refresh rates. My card limits me to 1920×1080 at i30 or 1920×1080 at i25, and only lets me use this mode on my LCD when I really need it on a CRT. Even if you can coax the video card to switch to a particular mode, this is quite a fragile state of affairs as full-screen games will switch to a different (and likely progressively scanned) mode.

Comments Electronics LCD shutter glasses adaptor Quake Stereoscopy

I hope that those of you who celebrate it had a good Christmas break and will have an excellent new year! I recently attempted to repair a DVD camcorder that had been dropped; the eject button no longer worked, though the disc could be ejected by connecting to camera to a PC, right-clicking the DVD drive that subsequently appears in Explorer, then selecting Eject. I started by removing all of the screws around the affected area, but the plastic casing remained strongly held together by some mysterious internal force.

Comments ATtiny13 AVR Electronics Remote control Repairs

Following the STM8S tutorial in my previous post, I've tried to put the chip to some practical use. My initial experiments into producing a video signal proved unsuccessful; I managed a static image using hard-coded delay loops, but when trying to use interrupts to trigger the generation of scanlines the timing was all wrong and without an oscilloscope or a working simulator I couldn't find out what was wrong. I decided to turn my attention from picture to sound. VGM files store game music by logging the data written to the sound chips inside the console or computer directly along with the delay between writes.

Comments Electronics STM8S VGM

STMicroelectronics recently released the STM8S-Discovery, an exceedingly cheap (RRP $7) evaluation kit for one of their 8-bit microcontrollers. It features the microcontroller itself (an STM8S105C6), running at up to 16MHz and offering 32KB of program memory, 2KB of RAM and 1KB of data EEPROM. This microcontroller has a solid set of on-board peripherals, including four timers (one advanced, one general-purpose, and one basic), SPI, I2C, UART, and ADC – so there are plenty of connectivity options.

Comments Electronics STM8S

In addition to the Tetris game from the previous post, I've added an implementation of snake to the ATmega168 project. Click to watch a gameplay video on YouTube. Either game can be selected from a menu that appears when the circuit is powered on. To exit menus I've added a second fire button; this allows you to step back to the main menu to pick a different game if need be. The source code and binary can be downloaded as before. I've written a number of different Snake implementations in the past.

Comments ATmega168 AVR AVR TV game Electronics PAL TV tvText

The tvText library I discussed last entry allows you to display text on a PAL TV in black and white using a 20MHz ATmega168 and a pair of resistors. If this doesn't sound terribly exciting, it's probably because it isn't. However, if you bear some limitations in mind and change the font, you can use this text output as a more general tile-mapping system and use it for games that employ simple graphics. The new circuit, featuring five sloppily-wired input buttons. I added five buttons to the test circuit — up, down, left, right and fire — to act as game input.

Comments ATmega168 AVR AVR TV game Electronics PAL TV tvText

Nearly a month since my last update - my, how time flies when you're having fun (or a heavy workload). I ended up building myself a cheap and cheerful SI Prog programmer for AVR development. After installing the development tools, scanning through the documentation and writing the microcontroller equivalent of Hello, World (flashing an LED on and off) I needed to find a suitable project. The first one was getting to grips with V-USB, a software USB implementation for AVRs. All you need for this are a couple of I/O pins, a few configuration file changes to set your USB device's vendor ID, product ID and device class, and a few lines of C code to actually implement your device.

Comments ATmega168 AVR Electronics PAL TV tvText USB

Work commitments have left me with little time to pursue my own projects of late, hence the lack of updates. A chap named Jeremy contacted me with problems relating to the IThumbnailProvider code I'd posted here before. We narrowed it down to a 64-bit issue, demonstrated by the fact that the thumbnails appeared in the file open dialog of a 32-bit application, but not in Explorer. Not having a 64-bit version of Windows to tinker with, I was unable to help, but he found the solution was to register the assembly using the 64-bit version of regasm.

Comments 16F84 BBC BASIC Clock Electronics IThumbnailProvider PIC TI-83+

To achieve smooth, glitch-free 3D in an ideal world, one would like to be able to alternate between left and right eye views every time the monitor refreshes. You could then use the monitor's vertical synchronisation pulse to alternate which eye shutter is currently open. Relying on software is not so bad if you can guarantee that you will be able to keep up with the video hardware and output alternating frames without dropping any. This is pretty much impossible with today's complex operating systems running any number of background tasks that could interfere with your render loop at any moment.

Comments Electronics LCD shutter glasses adaptor Stereoscopy

The Sega Master System supported 3D LCD shutter glasses to provide a more immersive (if somewhat flickery) playing experience. Having caught wind of an eBay member selling compatible glasses for $9 and being rather interested in stereoscopy I decided to experiment a little for myself. LCD shutter glasses with adaptor The glasses are pretty simple; they consist of two LCD panels that can be "switched on" to block light from passing through to each eye. A 3.5mm stereo jack plug provides the electrical connection.

Comments Electronics LCD shutter glasses adaptor Stereoscopy

It's been a while since I last posted, and unfortunately this post is to do with Sony remote controls again. This time I'm attempting to use Sony (or compatible) remote controls to control software running on a Windows PC. I've recently been watching more films in PowerDVD, and some of the keyboard shortcuts (eg Ctrl+P for the menu) are a little difficult to hit in the dark and from a distance. I have a ready supply of universal remote controls as well as the PlayStation 2 DVD remote control, all of which work with the SIRCS protocol.

Comments Electronics Remote control

Some time ago I was working on a simple Z80-based computer. It has a PS/2 keyboard and mouse port for user input, and these are implemented using a large number of discrete parts - transistor drivers with all manner of supporting latches and buffers. The AT protocol (which the PS/2 keyboard and mouse inherit) is entirely implemented in software by the Z80. On the one hand this design has a certain purity, but it ties the CPU up every time data is to be transferred. The keyboard sends data when it feels like it, so if you wished to perform some function based on a key press event you'd need to poll the port periodically, assuming that if communications time out there's no key waiting.

Comments 16F84 Electronics PIC Remote control Z80 Computer

The only major hardware modification since last time is the addition of another 32KB SRAM. Click to toggle labels This appears as two 16KB pages in the $4000..$7FFF slot. Currently only the first page is used for OS variables and scratch space, freeing up the upper 32KB entirely for BBC BASIC's use. One other minor hardware addition is support for a dual-coloured LED on the control port. This LED will be used to signify file access - reads by a green LED and writes by a red LED. As such I haven't implemented a proper file system, but typing SAVE "FILE" or LOAD "FILE" at the prompt will transfer data between the Z80 RAM and a 24LC256 32KB EEPROM.

Comments CHIP-8 Electronics Z80 Z80 computer

Dates, times and backlights
I'm using a DS1307 real-time clock to provide the computer with real-time date and time functions. It's a great little chip - all it needs is power, two lines for I2C communications, a 32768Hz crystal between two pins and a back-up battery to keep it ticking when main power is removed and it's happy. That accounts for seven pins; the last remaining pin can be used as a one-bit output (you can set it to a high or low state in software) or it can be configured to output a square wave at 1Hz, ~4kHz, ~8kHz or ~32kHz.

Comments BBC BASIC DS1307 Electronics Z80 Z80 computer

Cheers for the comments. As EasilyConfused pointed out, I have done calculator programming in the past, which makes this much easier - learning Z80 assembly to program a calculator influenced the choice of CPU in this computer, and porting BBC BASIC to the calculator showed that with a minimal amount of code to sit between it and the hardware you'd have a decent operating system with very little work. And if a Terminator-related name is good enough for the UK military, it should be good enough for this project...

Comments Electronics Z80 Z80 computer

This computer needs a name - I'd welcome any suggestions! I have built a circuit on another piece of stripboard that will handle memory, clock signal generation and the Z80 itself. A few posts ago I was wondering about how I'd partition memory. To date I've been using a very simple circuit where the lower 32KB of addressable memory is mapped to ROM and the upper 32KB is mapped to RAM. As my ROM chip is 128KB and I have two 32KB RAM chips, this seems a bit wasteful. The memory layout I'm now using is quite simple: the upper 32KB is still mapped to RAM.

Comments BBC BASIC Electronics Z80 Z80 computer

LCD Timing
Last time I discussed the hardware I mentioned I had LCD timing issues. I have finally resolved them, but this has been the most time consuming part of the project so far. The first thing to sort out was the LCD's E pin. Once you have set up the LCD's input pins to a state where they're ready to read or write data, you need to drive this pin high. I had had some success by holding it high permanently and relying on the Z80 to set all the other to the right state at roughly the same moment, but this was inaccurate and resulted in occasional display glitching.

Comments Electronics Emerson LCD PG12864LRS Z80 Z80 computer

A common problem with software that uses the parallel port is that is hard-coded to use particular port addresses, such as 0x378 for LPT1. This is all well and good on older machines that have integrated or ISA ports that can be assigned this base address, but newer machines with PCI cards don't get any choice over which port address range is assigned to the parallel port. Programming an AM29F010B with a PCI parallel port. The supporting software for the Willem programmer has this problem, and so far I've been using an old XP laptop with a flaky WiFi adapter to program chips.

Comments Electronics Remapped IO.DLL Willem

A computer needs some way of interacting with the outside world via input and output devices. It's about time, then, that the Z80 computer project acquires a section dedicated to I/O. The Z80 differentiates between memory and I/O devices, though both share the data bus and the address bus. You can control I/O devices using the in (input) and out (output) instructions. When you input or output you must specify a device address and a value or target register. For example,
in a,($20) ; Read a value from device $20 and store it in A.

Comments Electronics LCD PG12864LRS Z80 Z80 computer

Now armed with a flash programmer, I thought it about time to try and build a Z80-based system. Click for video (829KB WMV) Not much to look at, and it doesn't do much either. The large IC in the bottom-left, prominently marked Z, is the Z80 itself. To its left is a 555, generating a ~220Hz clock signal (yes, Hz, not MHz or even kHz). Above the Z80 is another large chip - this is the 128KB flash ROM. The eight parallel wires between them are the address bus - only A0 to A7 are connected. This only lets the Z80 address 256 bytes, but that should be enough for testing.

Comments Electronics Z80 Z80 computer

I've decided to switch to a regular 10MHz Z80 rather than a Z180, given the difficulty of using an SDIP 64. I now have a DIP 40 Z80 ready for use, but as I don't have the programmer for the Flash chip (which will hold the OS) there's not much I can do with it physically. I have therefore cobbled together a basic emulator to help develop some of the software beforehand. To cut hardware costs I'm going to try and handle input in software. One bit of hardware I'm planning on having is an eight-bit open collector I/O port.

Comments Electronics Emulation PICAXE PICAXE-28X1 Z80 Z80 computer

The next component I thought I'd experiment with is the RAM. The project is an analogue recorder - a circuit that samples an analogue input periodically and saves it in RAM, and can be configured to play the recorded signal back afterwards. Yes, it says plating. A single RAM chip offers 32K with an eight-bit word size. This requires fifteen lines to address it, A0..A14. The PICAXE-28X1 that is to control the circuit does not have enough output pins to be able drive this address bus and a data bus (to transfer values to and from RAM) and a still have enough pins left over to control the various components.

Comments Electronics PICAXE PICAXE-28X1 Z80 computer

I enjoy dabbling with low-level programming, but have never actually built a computer to run these programs. I think it's time to correct that, and as the BBC BASIC project has required me to develop an almost complete Z80 OS (the only thing that's left for the TI-OS to do is manage files) I thought a Z80 computer would be a good start. The planned specs are (as a starting point):
10 MHz Z80180 CPU;64KB RAM (2 32K×8 SRAM chips);128KB Flash ROM;Graphical LCD;Simple joypad input;Keyboard input (AT using either software AT routines or dedicated microcontroller).

Comments Electronics LCD PG12864LRS PICAXE PICAXE-28X1 Z80 computer

PlayStation controllers are relatively comfortable, and I have a number of them knocking about. From top to bottom - PS2 IR remote control and receiver; Guitar Hero wireless Kramer and receiver; black PS2 DualShock 2 analogue joypad; a pair of grey standard PS1 digital joypads. As I've learned in the past, a decent gamepad can help with certain games. Of course, what's much more fun than playing the games is trying to work out how these controllers work. The byte-level protocol is very simple; the PlayStation pulls a select line low (used to grab the attention of the controller) then pulses the clock eight times, writing a bit at a time onto one line and reading another bit at a time from another.

Comments C# Electronics

My work with the VDP in the Sega Master System made me more aware of how video signals are generated, so thought it would be an interesting exercise to try and generate them in software. This also gives me a chance to test Brass 3, by actively developing experimental programs. I'm using a simple 2-bit DAC based on a voltage divider, using the values listed here. This way I can generate 0V (sync), ~0.3V (black), ~0.6V (grey) and 1V (white). My first test was to output a horizontal sync pulse followed by black, grey, then white, counting clock cycles (based on a 6MHz CPU clock).

Comments Electronics PAL TV Z80

The TI-83+ lacks something the 84+ series has - a USB port. Enter the VMusic2. This low-cost (£25) module offers a USB host controller with a simple serial interface that can be used to read/write FAT-formatted USB mass storage devices. It can also play MP3 files straight from the drive! This is all very well, but the TI doesn't have a standard serial port either. To handle communications between the two, therefore, is a PICAXE-28X1 microcontroller. The TI can then run a program that communicates using its standard linking protocol.

Comments Electronics TI-83+ USB

I've been wanting to attach an SMS control pad to my PC (and be able to use it to play games with) for a while, so put in an order from those excellent chaps at Rapid for the parts needed. The joypad (as I've now learned from disassembly) is very primitive - 6 normally-open switches, each connected between a pin on the DE-9 connector and ground. The accepted layout adapter uses the 25-pin parallel port, connecting ground to pin 18, power to pin 1 (not that the control pad uses this pin) and 7 further connections from D0 to D6 for the buttons.

Comments C# Cogwheel Electronics Sega

What's that in the bottom left hand corner? Kerm Martian has added a PS/2 port to his calculator (click the picture for better pictures and the original thread). He has been developing a shell, entitled DoorsCS (click for website) which sports an impressive set of GUI controls - hence the mouse!

Comments Electronics Emerson TI-83+

Sorry about the lack of updates, but I have been incredibly busy with work related programming. One small project I've had a chance to update is Emerson - my keyboard and mouse library for the TI-83 series calculator. I know, I can't type layout. Download the library (and demo) here.

Comments Electronics Emerson TI-83+

I had another go with my AT protocol routines to see if I could persuade a PS/2 mouse to do anything. It would appear that I could... Click to view a video clip (1MB WMV) There are two cables for the mouse as there were for the keyboard - one goes to the TI, the other goes to the power supply. The mouse is put into the lowest resolution mode (the cursor is moved 1 pixel per mm). There's a demo for anyone with a TI-83 Plus and an adapter. It also contains a keyboard demo - and there's a video of that demo here (1MB WMV).

Comments Electronics Emerson TI-83+

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