PIC IPS - (Still) Work in progress!  

Table of contents

Purpose

Many things in our daily life have their origin in space development. For example the teflon frying-pan or the bal pen. So why not use some approved and working concepts for developing a universal microcontroller CPU board.

Based on a PIC 18F458 from Microchip the presented board will run IPS (Interpreter for Process Structures) as it's operating system. IPS is in use as the operating system of some amateur radio satellites for example the AMSAT OSCAR-40 or AO-40 for short. More infos about IPS can be found at the AMSAT IPS page (DOS, Windows) or at IPS for Linux/UNIX. IPS is something like Forth which is also used in a lot of space applications shown on this page at NASA.

This Board is just a prototype design. It does not use SMD components (except 1 component) and is only a single sided PCB (with some links). So there should be no problem for building your own IPS board. No need for making double sided PCB's and soldering super small SMD parts. There will be another version of this board using only SMD parts and double sided PCB. This will shrink the board size by a factor of 2 to 3.

There will be also an expansion board which fits onto the IPS board.

 


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Schematics

The IPS board consists of the MCU (a PIC 18F458), 2 x 32K SRAM, 64K EEPROM, 74HCT537 address latches, a MAX232 RS232 driver, I2C bus, 8 x I/O select, 5V power stabilisation, reset circuit and the connectors. There will be an expansion board with additional features like more EEPROM, Real Time Clock with battery backup, LCD, Buttons and DDS.

For the RS232 connecter I used a RJ45 connector because of space. The pins are numbered the same as on a conventional DB9 RS232 connector. So pin 1 on the DB9 is pin 1 on the RJ45 and so on. To connect the IPS board to a PC use a strait through cable from RJ45 to DB9 and Hyperterm on your PC. Set hyperterm to 9600 baud, 8 databits, no parity, 1 stop bit and hardware handshake. The last is important when uploading programs to the IPS board.

The PCB

The board layout using only one layer is not perfect nevertheless was it possible to keep the size of the board at nearly the size of a half euroboard. By consequent usage of SMD parts and a multilayer PCB the size of the board can be dramaticaly reduced. But as noted above, the main intention was a prototype which can easily be built.

The PCB
Image 1: The PCB

  Component positions
Image 2: Component positions

The PCB
Image 3: Component positions

   

You can download a PDF File with the schematic and the PCB here.
If you dont have the Adobe Acrobat Reader installed on your machine you can find it here

Pictures of the finished PIC IPS

Here you can see how the PIC IPS looks during different stages of the building process and how it looks when it's finished. A picture says more than thousand words.

The etched PCB
Image 4: The etched PCB

  Finished PCB
Image 5: The finished PCB with all components

The board including the AddOn board
Image 6: The board including the AddOn board

  Both boards stacked together
Image 7: Both boards stacked together

The boards in action
Image 8: The board in action

Notes & Comments

Even if the PIC IPS PCB is not double sided and there are no SMD parts you should read the folowing notes when building one.

Credits

If you have any comments or sugestions just drop me a line.

73, OE1RIB