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FullDuplexSerial question — Parallax Forums

FullDuplexSerial question

DiverBobDiverBob Posts: 1,123
edited 2010-04-13 08:36 in Propeller 1
I was doing some experimenting with a Prop and FullDuplexSerialPlus.spin and a routine that was working with another prop chip doesn't work with the new prop. The only difference I can see is that the crystal freq is 8 MHZ on the prop that isn't communicating and the crystal was 10 MHZ on the one that did work. I didn't think this would make a difference but I can't see where else the difference might be. Could it be the crystal or should I look elsewhere?

Bob

Comments

  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2010-04-13 01:06
    Sorry Bob, there is just insufficient information to go on for us to say anything of consequence. Maybe if you attach the code archive and then we can see what you are trying to do, it may be that you are running at too high a baud rate for FDX to handle, hard to say.

    BTW, I hope that you have actually ruled out hardware fault, ensure your 8MHz Prop is actually working with a simple blinky program or something. Always go back to basics and be methodical (don't assume or skip steps) when troubleshooting, it saves so much time and frustration later.

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    *Peter*
  • Mike GreenMike Green Posts: 23,101
    edited 2010-04-13 01:08
    Remember that the Prop doesn't work in most cases if you use an 8MHz crystal and a PLL multiplier of 16x. You need to use PLL8X with both an 8MHz and a 10MHz crystal.
  • DiverBobDiverBob Posts: 1,123
    edited 2010-04-13 01:16
    I forgot to say I was running PLL8X for both cases.

    Bob
  • Mike GreenMike Green Posts: 23,101
    edited 2010-04-13 01:23
    FullDuplexSerial should work fine up to maybe 115.2KBps with a 64MHz system clock. Like Peter said, what you've described should work. If it doesn't, then there's something you haven't described that's the root of the problem.
  • LeonLeon Posts: 7,620
    edited 2010-04-13 08:36
    Output 'U' continuously and check the output pin with a scope; you should have alternating 1s and 0s. You can also check the bit time.

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    Leon Heller
    Amateur radio callsign: G1HSM
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