After getting the Membership Card to work with the serial interface circuit on my big breadboard, I decided it would be good to move the circuit to a smaller breadboard – one that only had the one project on it and that could stand in for an actual completed project.
I should never change something once it works. It took me most of the night to get the circuit to run on a different breadboard. When I moved it I decided to move some of the pins around on the PICAXE-20X2; then I had to troubleshoot those connections, change the control pin IDs in the software, rebuild, reload, do it again and again.
On the bright side, I’ve been watching some interesting shows on Hulu.com while I work on this stuff…
In any case, I’ve discovered that I can’t actually read the data bus with the 20X2 to send data back to the PC. The pull-up resistors on the data switches, um, pull up the bus to +5V when I read the bus, and all I get back at the PC are ones. I need to rethink how I’m going to get the data from the Membership Card back to the PC – I’m not sure I have enough data bits on the 20X2 – though I may be able to do something with diodes so that I can use port B to both write to the Membership Card and then read back from it. Worth a try…
Maybe this weekend I’ll make a couple more steps forward – and avoid the steps back.