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Palm-Vision - Parallel/Serial interface

Interface components
  • 8051 compatile microcontroller (you would probably want to use EPROM version: 87..51 or flash version 89..51. (I've choosen AT89S8252, because it can be easily programmed in place using SPI interface). Yes, that's right - you will have to store the program below in your circuit's memory.
  • MAX232 (+5V -> +-12V converter)
  • Parallel port female 25 pin connector (PP)
  • Serial port male 9 pin connector (SER)
  • XTAL - 11.0592 MHz crystal (looks like it is too slow, but for now the program works ony with this speed)
  • Cosc1,Cosc2 - 20-40pF capacitors (2 pcs.)
  • C (not labelled on the schematic) - 1 uF capacitors (5 pcs.)
  • Creset - 2,2 uF capacitor
  • Reset button - or you can use the screwdriver... (not needed in usual cases)

The interface I built looks like this. As you can see, you don't need a circuit board - all you have to do is connect all things together. Simple?
Interface schematic

Interface program download HEX file
Any comments?
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(C) 1999 Szymon Ulatowski