Arduino Yun 40 to 50 channel data acquisition system

controler_code.ino

/*
 40 to 50 channel data acquisition
 
 TODO: Detection of optional channels 41 to 50
 TODO: Collect only when data is incoming
 
 created 09 April 2014
 by Joseph Warner
*/

#include <stdio.h>
#include <digitalWriteFast.h>

// Define the pins on the MUX from lsb
#define MUX_PIN_1 2
#define MUX_PIN_2 3
#define MUX_PIN_3 4
#define MUX_PIN_4 5
#define MUX_PIN_5 6
#define MUX_PIN_6 7

// Define the ADC pins from LSB
#define ADC_PIN_1 8
#define ADC_PIN_2 9
#define ADC_PIN_3 10
#define ADC_PIN_4 11

// Defines the channels available and their addresses (offset by -1)
#define REQUIRED_CHANNELS 39
#define CHANNEL_41 40
#define CHANNEL_42 41
#define CHANNEL_43 42
#define CHANNEL_44 43
#define CHANNEL_45 44
#define CHANNEL_46 45
#define CHANNEL_47 46
#define CHANNEL_48 47
#define CHANNEL_49 48
#define CHANNEL_50 49

// Current channel we're getting data from
unsigned int addr = 0x0;
// Time of the collection period (us)
unsigned int collectionPeriod = 100*1000;

// Array of the 10 optional channels describing if they are or are not
// in use.
unsigned int channels[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

void setup() {
  // Set MUX pins as output pins
  pinModeFast(MUX_PIN_1, OUTPUT);
  pinModeFast(MUX_PIN_2, OUTPUT);
  pinModeFast(MUX_PIN_3, OUTPUT);
  pinModeFast(MUX_PIN_4, OUTPUT);
  pinModeFast(MUX_PIN_5, OUTPUT);
  pinModeFast(MUX_PIN_6, OUTPUT);

  // Set ADC pins as input pins
  pinModeFast(ADC_PIN_1, INPUT);
  pinModeFast(ADC_PIN_2, INPUT);
  pinModeFast(ADC_PIN_3, INPUT);
  pinModeFast(ADC_PIN_4, INPUT);

  // Begin serial access
  Serial.begin(9600);

  while(!Serial);
  Serial.println("Serial data logger started\n");
}

void loop() {
  unsigned int i = 0;
  unsigned int data = 0;
  char dataOutputBuffer[20];

  // Reset addr to 0
  addr = 0;
  writeAddrToMux();

  //Determine the channels to use (1-40 + which optional?)
  detectChannelsInUse();

  // Start timing
  unsigned long startTime = micros();
  unsigned long currentTime = micros() - startTime;

  while (currentTime > collectionPeriod) {
    // Format the data from this collection cycle
    sprintf(dataOutputBuffer, "%08u;%06x;%04x",\
      currentTime, addr, getDataFromAdc());
    // Have MUX move to the next address to allow time for hardware changes
    nextAddrToMux();
    Serial.println(dataOutputBuffer);
    currentTime = micros() - startTime;
  }
}

// Gets data from the ADC
unsigned int getDataFromAdc() {
  unsigned int data = 0x0;

  data ^= digitalReadFast(ADC_PIN_1);
  data ^= (digitalReadFast(ADC_PIN_2) << 1);
  data ^= (digitalReadFast(ADC_PIN_3) << 2);
  data ^= (digitalReadFast(ADC_PIN_4) << 3);

  return data;
}

// Determine which channels are connected and enable data collection
// from them.
void detectChannelsInUse() {
  // TODO make functional. Currently placeholder.
  channels[0] = 0;
  channels[1] = 0;
  channels[2] = 0;
  channels[3] = 0;
  channels[4] = 0;
  channels[5] = 0;
  channels[6] = 0;
  channels[7] = 0;
  channels[8] = 0;
  channels[9] = 0;
}

// Increments the MUX to the next address
void nextAddrToMux() {
  if (addr < REQUIRED_CHANNELS) {
    addr++;
  } else if(channels[0] == 1 && addr < CHANNEL_41) {
    addr = CHANNEL_41;
  } else if(channels[1] == 1 && addr < CHANNEL_42) {
    addr = CHANNEL_42;
  } else if(channels[2] == 1 && addr < CHANNEL_43) {
    addr = CHANNEL_43;
  } else if(channels[3] == 1 && addr < CHANNEL_44) {
    addr = CHANNEL_44;
  } else if(channels[4] == 1 && addr < CHANNEL_45) {
    addr = CHANNEL_45;
  } else if(channels[5] == 1 && addr < CHANNEL_46) {
    addr = CHANNEL_46;
  } else if(channels[6] == 1 && addr < CHANNEL_47) {
    addr = CHANNEL_47;
  } else if(channels[7] == 1 && addr < CHANNEL_48) {
    addr = CHANNEL_48;
  } else if(channels[8] == 1 && addr < CHANNEL_49) {
    addr = CHANNEL_49;
  } else if(channels[9] == 1 && addr < CHANNEL_50) {
    addr = CHANNEL_50;
  } else {
    addr = 0x0;
  }
  writeAddrToMux();
}

// Writes the current addr to the MUX
void writeAddrToMux() {
  digitalWriteFast(MUX_PIN_1, addr & 1);
  digitalWriteFast(MUX_PIN_2, addr & (1 << 1));
  digitalWriteFast(MUX_PIN_3, addr & (1 << 2));
  digitalWriteFast(MUX_PIN_4, addr & (1 << 3));
  digitalWriteFast(MUX_PIN_5, addr & (1 << 4));
  digitalWriteFast(MUX_PIN_6, addr & (1 << 5));
}