4 comments on “Trivial communications

  1. Pingback: Communication between Arduino and a Commodore 64 « freetronicsblog

  2. Hi,

    This was really useful but I have gone down the rs232 route using this scematic http://ilkerf.tripod.com/chard/rs232c96.txt

    It isn’t working… at the moment. I was wondering if you knew how to bypass the CTS handshaking bit that I think my arduino is having trouble with. I may be barking up the wrong tree with that though and it is entirely possible my BASIC code is letting me down (I have not learnt ASM yet). I only want to arduino to recieve and never send.

    Thanks for any help with my poorly explain problem.

    • I’ve only looked at CTS/RTS handshaking a little bit, so I’m not sure I can be much help. I’ve been using a Max3100 to convert SPI to RS-232, but I’ve ignored handshaking so far and only connected Rx, Tx, and ground signals. You could try turning off handshaking and see what happens – you’ll probably drop some characters, but not all of them.

      I’d guess BASIC on the C64 might be a bigger problem, though – you just might not be able to get the timing accurate enough for the other side to understand it. That was the main reason I looked at synchronous communication. It freed me from having to worry about any of the timing constraints.

      • Thanks, I found a solution. First off I had RX and TX wires mixed up in code….. 2 hours to figure that tiny thing out, doh! Still it tuns out handshaking was an issue, the c64 was waiting for the arduino to become ready. I solved this by looping back (Loop back handshaking) the CTS and RTS wires so they connect to each other on the same device. This meant I both are always ready to send if they are not recieving chars and ready to recieve if they are not sending. I am getting a reliable 300 baud, fine for the amount of chars I want to send but it worked fine on 1200. It hasn’t dropped a char yet. I did figure out that the signal needs to be inverted on the arduino end though, weird things happen otherwise.

        I really like your blog, I will definately try my hand at ‘bit banging’ but for now I am familiar with rs-232.

        My first stop is a c64 twitter client and then is it web feeds.

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