Send Note Events on digital input changes

We want to send Note events when a button connected to the (up to) 128 DIN pins is pressed/depressed.

Copy the SDCC skeleton into a new directory, open the main.c file and enhance the hooks like described below. Thereafter type "make" in the command shell, and upload the new project.hex file to the core.

Within the Init() function, you have to specify, how many DINX4 shift registers are connected to the core:

// This function is called by MIOS after startup to initialize the 
// application
void Init(void) __wparam
  // set shift register update frequency
  MIOS_SRIO_UpdateFrqSet(1); // ms

  // we need to set at least one IO shift register pair
  MIOS_SRIO_NumberSet(16); // for 128 pins

  // debouncing value for DINs

We add the code which should be executed on button movements to the DIN_NotifyToggle() function:

// This function is called by MIOS when an button has been toggled
// pin_value is 1 when button released, and 0 when button pressed
void DIN_NotifyToggle(unsigned char pin, unsigned char pin_value) __wparam
  MIOS_MIDI_TxBufferPut(0x90); // Note Event at channel #1
  MIOS_MIDI_TxBufferPut(pin);  // just forward the pin number (0..127)
  MIOS_MIDI_TxBufferPut(pin_value ? 0x00 : 0x7f); // Velocity = 0x7f when 
                                                  // button pressed, else 0x00

A list of available MIOS function can be found here.

Last update: 2020-02-16

Copyright 1998-2020, Thorsten Klose. All rights reserved.