Timing issues with trying to do MIDI output with FullDuplexSerial

__red__ · 2011-10-21 05:55

When running the following program:

'**************************************************************
'* miditest                                                     *
'**************************************************************
CON
    _clkmode = xtal1 + pll16x
    _clkfreq = 80_000_000
    MIDI_OUT_PIN  = 20             'MIDI out pin
    MIDI_IN_PIN   = 21

    OPEN_DRAIN    = true          'if using the standard MIDI output circuitry TX must be open drain
    INVERT_TX     = false         'change if required

    BASE_OCT      = 0             'can go down to -2 or up

OBJ                                  'include 2 ViewPort objects:
 ser   : "FullDuplexSerial"
VAR
  long onems
PUB main | n, mode

  mode := 0
  if INVERT_TX
    mode |= 2
  if OPEN_DRAIN
    mode |= 4
  ser.start(MIDI_IN_PIN, MIDI_OUT_PIN, 31250, mode)
  waitcnt(cnt + clkfreq * 3)
  onems := clkfreq / 1000
  repeat
    repeat n from 0 to 60
      send_note(n, 500)
    waitcnt(cnt + clkfreq * 10)

PRI send_note(pitch, duration)
  'send NoteOn message
  ser.tx($90)
  ser.tx((BASE_OCT + 2) * 12 + pitch)
  ser.tx($40)
  'wait for a while
  waitcnt(cnt + duration * onems)
  'send NoteOff message
  ser.tx($80)
  ser.tx((BASE_OCT + 2) * 12 + pitch)
  ser.tx($40)

My Logic analyzer shows that each serial character appears to take 5 seconds to send.

I've run my other code on the same board so i don't think it's a crystal issue.

Anyone have any insight as to my simple mistake?

Thanks,

Red

__red__ · 2011-10-21 05:58

It took my posting for all to see my idiocracy to see the issue:

80_000_000 with 16x.

I'd delete the thread but there is no delete function that I can see.

I now return you to your previous programming...

kuroneko · 2011-10-21 06:02

Setting _clkfreq to 80M is fine (equivalent to _xinfreq = 5M). You simply start your serial device with the wrong parameters. Baud rate is last, mode second to last.

__red__ · 2011-10-21 07:36

I spoke too soon it seems, I don't seem to be able to decode it. I'll work on it some later this evening after work. Thanks for the feedback thus far.

Red

Timing issues with trying to do MIDI output with FullDuplexSerial

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