The converter runs at 9600 baud, 89C2051 and outputs each byte received on a centronics style parallel port, together with a nominal 50 microsecond strobe. The converter buffers up the bytes received if busy is active, and is bidirectional – when the sample switch is pushed, the converter samples the parallel port and transmits the value back out the serial port. All the parameters are adjustable in the code. This is the figure for the connection circuit;
The example program should be assembled with the shareware assembler TASM. This assember is actually a very good assembler for 8051, (and other 8 bit micros) with 32 bit arithmetic, and a linux version available. TASM is produced by Squak valley software. The serial-to-parallel example program was intended to run on an AT89C2051 using the prototype board that was originally supplied as part of the evaluation kit in our programmer. But the circuit is pretty darn simple, and a competent electronics person could build one up themselves, by hand, if they need to. The code should run on any 8051 target with modification to the port locations – the equates for the pin & port locations are near the start of the code.
Note the pin functions are not shown on the circuit, as the circuit was intended to be a general purpose evaluation board, not just a serial to parallel converter.
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