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Embedded systems :: Previous projects
   

 

Over the years I've developed many projects and even entire systems that featured embedded microprocessors and controllers. Here follows a brief listing of those I can remember at the time of writing.

Bushtronics remote bore monitor

This featured two designs, a remote unit based on a 6805 microcontroller and a base unit built on a Microbee Z80-based computer.

The remote unit had to run on almost no power so it slept for the majority of the time, every minute a CMOS timer would wake the circuit, the micro would read the water level in the tank and trough and radio this information to the base unit. This was all written in 6805 assembler including the serial bit-banging to the RF modulator as the '05 didn't have a serial port. The system could handle up to 16 of these remote units.

Back at base the circuit consisted of a daughter board that plugged into an expansion socket on the Microbee. This board held an EPROM with the application code and other circuitry required to receive the demodulated serial data. The whole application, including the user interface which allowed the user to edit remote bore names, was written in Z80 assembler.

This system won an Institute of Engineers design award.

Degree-hour meter

This mostly analogue design measured the difference in temperature between inside and outside a building and produced a count indicating the amount of such difference over time. It was used to measure the thermal efficiency of a building.

Front end processor

A 6809-based master control board for the Torrens Industries building control system. This was a 12x12" board packet with IO and bank-switched memory. It had total control of a building and could upload a version of p-code to be interpreted by an on-board interpreter, all written in 6809 assembler.

This board controlled slave systems around a building using HDLC synchronous protocol over the fibre optic links of the BMAC system we installed in the ASIO headquarters in Canberra.

Fire brigade turnout system

This was an entire system featuring 19" racks packed with IO and processor cards, all of which I designed and built. The master controller board used a 64180 processor, once again with banked switched RAM and EPROM and many PIO, SIO, RTC chips all glued together with an 84-pin Altera gate array.

EPROM emulator

Called the Romulator this was my own product that was on the market for several years. It could emulate EPROMs from 2-32k (the largest available at the time) and accept data in either Intel or Motorola HEX formats. The user could also inspect/modify memory and insert software breakpoints. The code was written in Z8 assembler and the device used a 22V10 gate array to hold all glue logic.

This device earned me the ACT Inventor of the Year award.

BMR control panel

For this Bureau of Mineral Resources project I had to write the entire user interface without any hardware being present. As the hardware had been specified I wrote the code in C with all IO calls going to a mock panel displayed on a computer screen that I designed from the hardware specs to look like the finished panel.

When the hardware was ready it was a fairly simple matter to replace the IO library with one that talked to the real world.

Logic analyser

A simple 16-channel 10MHz logic analyser that displayed the captured data on an oscilloscope by modulating the X, Y and Z axis. I used this for years until I could afford the real thing.

PCB design

On most of the above projects I did all the PCB design, initially using Bishop graphics decals and tape on translucent paper and then with Protel CAD software (I was a very early adopter of CAD and a beta tester for Protel at the time). I also did freelance PCB design for various electronics businesses around Canberra.

 

 

   
 

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