ESP_Digital_MIC_To_DAC_Success.ino

//  ESP_Digital_MIC_To_DAC
//    by koichi kurahashi 2016-06-08
//
//  read SPM0405HD4H and write to MCP4921
//
//  Thanks:
//    http://www.pwv.co.jp/~take/TakeWiki/index.php?arduino%2FDACを試す
//    arduino/DACを試す
//


#include <Arduino.h>
#include <SPI.h>

extern "C" {
#include <user_interface.h>
}


//
//  SPM0405
//
#define kOutClock 5   // to   CLK
#define kInSignal 4   // from DAT
// L/R is connected to GND -> down edge mode


//
//  DAC MCP4921
//
//  GPIO 13 - Pin 5 SDI
//       14 -     4 SCK
//       15 -     3 !CS
//       16 -     8 LDAC
//                1, 9, 11, 13 - Vcc
//               12            - Gnd
//                1 - 0.1uF - 13
//

const int kPinLatchDAC  = 16;


void setup() {
  // put your setup code here, to run once:
  Serial.begin(230400);

  pinMode(kOutClock, OUTPUT);
  pinMode(kInSignal, INPUT);

  setupDac();
}

//  DAC init
//
void setupDac() {
  //  set pinMode
  pinMode(kPinLatchDAC, OUTPUT);
  pinMode(SS,           OUTPUT);

  //  init SPI for DAC
  SPI.begin();
  SPI.setBitOrder(MSBFIRST);
  SPI.setClockDivider(SPI_CLOCK_DIV8);
  SPI.setDataMode(SPI_MODE0);
}


//
//  loop
//

const int kMaxLoop   = 100;
const int kMaxDAC    = 4095;
const int kMaxRate   = 2000 / kMaxLoop;
const int kMaxOffset = kMaxDAC / 2;
const int kOutLoop = 10000 / kMaxLoop;
long a, b;  //  dummy wait
void loop() {
//  int min = 32767;
//  int max =-32767;
  while (1) {
    for (int i = 0; i < kOutLoop; i++) {
      int count = 0;
      for (int l = 0; l < kMaxLoop; l++) { //  25n
        digitalWrite(kOutClock, LOW); // low 212.5n
        a++; b++;
        if (digitalRead(kInSignal) == HIGH) {
          count++;
        }
        else {
          count--;
        }
        if (l < kMaxLoop - 1) {
          digitalWrite(kOutClock, HIGH);  // high=225.0n
          digitalWrite(kOutClock, HIGH);  // high=225.0n
        }
      }
      count = count * kMaxRate + kMaxOffset;
      outputToDAC(count);
//      if (count > max) max = count;
//      if (count < min) min = count;
    }
//    Serial.print(min);
//    Serial.print(",");
//    Serial.println(max);
    ESP.wdtFeed();
  }
}



void outputToDAC(uint16_t inData) {
  inData = inData & 0xfff;
  digitalWrite(kPinLatchDAC, HIGH);
  digitalWrite(SS, LOW);
  SPI.transfer16(inData | 0x3000);
  digitalWrite(SS, HIGH);
  digitalWrite(kPinLatchDAC, LOW) ;
}