mockband/MockBand.ino

#include <stdint.h>
#include <Arduino.h>
#include <PluggableUSB.h>

#include "hid.hh" // Modified HID library: doesn't prefix each packet with ID
#include "instrument.hh"

//#include "blue.hh"  // Ginnie's blue guitar
#include "standard.hh"  // Standard pins

// How often do you want to send an update?
// Smaller number: lower latency, but more bounces
// Bigger number: higher latency
// 20ms feels pretty good to me
#define UPDATE_INTERVAL_MS 20

InstrumentButtonState buttonState;

void setup() {
  pinMode(STRUM_DOWN, INPUT_PULLUP);
  pinMode(STRUM_UP, INPUT_PULLUP);
  pinMode(TILT_SWITCH, INPUT_PULLUP);
  pinMode(BUTTON_GREEN, INPUT_PULLUP);
  pinMode(BUTTON_RED, INPUT_PULLUP);
  pinMode(BUTTON_YELLOW, INPUT_PULLUP);
  pinMode(BUTTON_BLUE, INPUT_PULLUP);
  pinMode(BUTTON_ORANGE, INPUT_PULLUP);
  pinMode(SOLO_GREEN, INPUT_PULLUP);
  pinMode(SOLO_RED, INPUT_PULLUP);
  pinMode(SOLO_YELLOW, INPUT_PULLUP);
  pinMode(SOLO_BLUE, INPUT_PULLUP);
  pinMode(SOLO_ORANGE, INPUT_PULLUP);
  pinMode(ANALOG_WAMMY, INPUT);
  pinMode(BUTTON_PLUS, INPUT_PULLUP);
  pinMode(BUTTON_MINUS, INPUT_PULLUP);

  // Initialize HID
  static HIDSubDescriptor node(_hidReportDescriptor, sizeof(_hidReportDescriptor));
  HID().AppendDescriptor(&node);  

  buttonState.axis[0] = 0;
  buttonState.axis[1] = 0;
  buttonState.axis[2] = 0;
  buttonState.axis[3] = 0;
  for (int i = 0; i < 12; i++) {
    buttonState.reserved1[i] = 0x0;
  }
  buttonState.finalConstant = 0x0200020002000200;
}

// The 3.3v Pro Micro is on the slow side.
// Our strategy is to poll button state as quickly as possible,
// send an update every 10ms,
// and hope we don't miss anything while we're doing USB stuff.
void loop() {
  register uint16_t buttons = 0;
  unsigned long next = 0;

  while (1) {
    unsigned long now = millis();

    buttons |= ~(0
      | (digitalRead(BUTTON_BLUE)   <<  0)
      | (digitalRead(BUTTON_GREEN)  <<  1)
      | (digitalRead(BUTTON_RED)    <<  2)
      | (digitalRead(BUTTON_YELLOW) <<  3)
      | (digitalRead(BUTTON_ORANGE) <<  4)
      | (digitalRead(TILT_SWITCH)   <<  5)
      | (digitalRead(STRUM_UP)      <<  6) // Not in USB packet
      | (digitalRead(STRUM_DOWN)    <<  7) // Not in USB packet
      | (digitalRead(BUTTON_MINUS)  <<  8)
      | (digitalRead(BUTTON_PLUS)   <<  9)
      | (digitalRead(SOLO_BLUE)     << 10) // Not in USB packet
      | (digitalRead(SOLO_GREEN)    << 11) // Not in USB packet
      | (digitalRead(SOLO_RED)      << 12) // Not in USB packet
      | (digitalRead(SOLO_YELLOW)   << 13) // Not in USB packet
      | (digitalRead(SOLO_ORANGE)   << 14) // Not in USB packet
    );

    if (now < next) {
      continue;
    }
    next = now + 20;

    buttonState.buttons = (buttons & 0b1100111111);      // All directly-mappable bits
    buttonState.buttons |= ((buttons >> 10) & 0b11111);  // Solo keys
    bitWrite(buttonState.buttons, 6, (buttons >> 10) & 0b11111); // Solo bit

    // I don't understand why any rational engineer would have done this.
    buttonState.hatAndConstant = (0x08
      ^ (bitRead(buttons, 6) << 4) // up
      // right << 3
      ^ (bitRead(buttons, 7) << 2) // down
      // left << 1
    );

    buttonState.axis[2] = analogRead(ANALOG_WAMMY) / 4;

    // Send an update
    HID().SendReport(0, (uint8_t *)&buttonState, 27);

    buttons = 0;
  }
}