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digiIOBela

Reads or writes a Bela digital pin with a changing pin number and direction.

This opcode requires the Bela Csound host. See Bela digital input and output for setup and pin ownership.

Syntax

digiIOBela(kstate, kpin, kdir)
digiIOBela(astate, apin, adir)

digiIOBela kstate, kpin, kdir
digiIOBela astate, apin, adir

Performance

All three arguments are required. Use three k-rate signals or three a-rate signals. The audio-rate form needs audio-rate pin and direction signals too, even when their values stay constant.

kpin or apin selects a Bela digital channel from 0 to 15. The opcode truncates fractional values and clamps the result to this range. The selected pin can change during performance.

kdir or adir sets direction. A positive value selects output. Zero or a negative value selects input. Use 1 for output and 0 for input.

kstate or astate must be a writable signal variable. The opcode has no separate output argument. In input mode, it replaces this variable with the pin reading, either 0 or 1. Read the variable after calling the opcode. Do not pass a literal or expression as the first argument when reading input.

In output mode, the opcode sends the variable's value to the pin. Positive values drive it high, while zero and negative values drive it low. Assign the value before the call. Output mode does not replace the variable with a pin reading.

The k-rate form sets direction and reads or writes once per control cycle. Direction and output writes persist for following digital frames until changed. The a-rate form sets direction and reads or writes each digital sample separately.

Selecting a different pin leaves the previous pin's state and direction in place. Avoid changing an externally driven input into an output unless the connected circuit supports that use. See digiInBela and digiOutBela for fixed-direction alternatives.

Examples

The example reads digital pin 0 and copies its state to digital pin 1. One call uses input mode and the other uses output mode. The input call changes kInput in place before the output value is assigned.

Supply a defined logic level to pin 0 and observe pin 1 with suitable logic-level equipment. Keep pin 1 free of other output drivers. During the final second, the example drives pin 1 low before ending.

It uses digiIOBela.csd, which must run on the Bela host.

Read one Bela pin and write its state to another
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<CsoundSynthesizer>
<CsOptions>
-d
</CsOptions>
<CsInstruments>
// The Bela host supplies ksmps. Match sr to the board's audio rate.
sr = 44100
nchnls = 2
0dbfs = 1

instr CopyPin
  kInput init 0
  kInputPin init 0
  kInputMode init 0
  kOutputPin init 1
  kOutputMode init 1

  // Input mode replaces kInput with the pin reading.
  digiIOBela(kInput, kInputPin, kInputMode)
  kOutput = kInput
  kTime = timeinsts()
  if kTime >= p3 - 1 then
    kOutput = 0
  endif
  digiIOBela(kOutput, kOutputPin, kOutputMode)
endin
</CsInstruments>
<CsScore>
i "CopyPin" 0 10
e
</CsScore>
</CsoundSynthesizer>

See also

digiInBela, digiOutBela, Bela digital input and output

Credits

Author Victor Lazzarini, 2018.