Serial communication problem
August 21, 2008
I am trying to interface my arm9 based single board comp to the PICAXE 28X1 (starter kit board). The idea is to interface the single board computer running Linux to my PICAXE over serial and try to send commands to it over the serial line. I wrote code for my PICAXE that can listen on the serial line and transmit the same characters back. The arm board recives characters sent by the PICAXE but for some reason characters sent by the arm board are not recieved by the PICAXE.
I have tried both the programming serial port - serrxd/sertxd combination and the general i/o pins - serin/serout combination. In both cases the characters sent by PICAXE are visible at the arm9 minicom terminal but the reverse always fails. The output (serial Tx) is run through a 330 Ohms resistor on output pin 0.
I have observed that if i short the V and one of the input pins the serin is able to read some garbage character from the input pin. The program is pretty simple
using programming serial port
ptr = 1 `Reset scratchpad pointer to 1
`Read just 1 byte command to scatchpad address 1
using the general i/o pins
serin 7, N4800, b1
serout 0, N4800, (b1)