Manchester Data Link

Manchester Coding

TransmitterĀ Source code

ReceiverĀ source code

I made a Transmitter/Receiver pair from a couple of PIC’s. The pair use a manchester coding system. This is a layer 2-ish solution. I put them on top of a 433 MHz rf and an IR layer 1.

I used the PICC Lite compiler from HI-TECH, which is pretty good but the version I have doesn’t handle bank switching properly.

The transmitter is a 12F675, with a 12C509 modulator for an IR data link layer or a 433 MHZ TX module from OATLEY for an RF data link layer.

Included in the source code package is the code for the 12C509 38/49 kHz IR modulator

The receiver is a 16F627 connected to an LCD display in 4 bit mode.

Look in the doc directory of the source for an explanation of the coding scheme.

Electronic Throttle Control

I developed a prototype Electronic Throttle Controller as my final year project at CPIT in 2001. The system consists of a 68HC11 based main board, a stepper motor and driver board, a pedal position sensor and an engine speed sensor.

An Electronic Throttle Controller replaces the mechanical linkage between a cars accelerator pedal and throttle. Breaking this linkage frees the designer to allow inputs from systems other than the drivers foot to control engine speed. Such a system can be used in launch/traction control systems, gearbox controllers and anti-stall systems.

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Main Board

The main board is a double sided PTH design, I was lucky to have a friend with connections in the PCB manufacture business, making this design possible with the non existent project budget. It is a fairly conventional 68HC11 expanded memory design.

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Stepper Motor Driver

The stepper motor driver is based on the ULN5804 motor driver IC from Allegro. I used a motor from an old 5 1/4″ floppy drive for the prototype demo. I housed it in an aluminium box with perspex lid for demonstration purposes.

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Engine Speed Sensor

The engine speed sensor is based on a dual element Hall effect sensor from Allegro. Below is a concept drawing for the sensor, and the potted prototype.

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