Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)
User avatar
By Mai Mariarti
#79054 YES.
It worked.
Now I have to find a hardware solution since this bit-banging is too slow.
http://playground.arduino.cc/Code/MCP3208
Here is the code I need to convert to run on ADS8344 and ESP8266.
That should be a good exercise for me.
Thanks again for all your help.


Code: Select allThis code uses the SPI library rather than bit-banging with digitalWrite() so is much more efficient. It can sustain about 32ksps with a 2MHz SPI clock on an Uno or Mega

Note that this code hard-codes the command bits:

  // command bits for MCP3304
  // 0000 = diff, ch0 = in+, ch1 = in-
  // 0010 = diff, ch2 = in+, ch3 = in-
  // 0100 = diff, ch4 = in+, ch5 = in-

(the read_adc function provides 3 differential input channels, I didn't bother to code up for the 4th differential channel)

Code:

// read the MCP3304 in quad differential mode, non-bit-banging version
//#include <Serial.h>
#include <SPI.h>

#include <HardwareSerial.h>

long ticks = 0;

// for Uno
//#define SELPIN 10    // chip-select
//#define DATAOUT 11   // MOSI
//#define DATAIN 12    // MISO
//#define SPICLOCK 13  // Clock

// for Mega2560 / Max32
#define SELPIN 53    // chip-select
#define DATAOUT 51   // MOSI
#define DATAIN 50    // MISO
#define SPICLOCK 52  // Clock

int readvalue;


void setup(){
  //set pin modes
  pinMode(SELPIN, OUTPUT);

  // disable device to start with
  digitalWrite(SELPIN, HIGH);

  SPI.setClockDivider( SPI_CLOCK_DIV8 ); // slow the SPI bus down
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode(SPI_MODE0);    // SPI 0,0 as per MCP330x data sheet
  SPI.begin();

  Serial.begin(115200);
}


void loop() {
  long ticks = millis();
  int A = 0, B = 0;

  A = read_adc(1);
  B = read_adc(2);

  // do whatever you want with these readings

  long tcnv = millis() - ticks;

  delay(100 - tcnv);
}

// non-bit-banging version
// channel ranges from 1.. 3 (not zero!)
// maximum clock frequency is 2.1 MHz @ 5V
//
// this is SPI_CLOCK_DIV8
// at DIV64, 512 in 60ms (8.5 ksps)
// at DIV32, 512 in 35ms (14.6 ksps)
// at DIV16, 512 in 22ms (23.3 ksps)
// at DIV8, 512 in 16ms (32 ksps)

int read_adc(int channel){
  int adcvalue = 0;
  int b1 = 0, b2 = 0;
  int sign = 0;

  // command bits for MCP3304
  // 0000 = diff, ch0 = in+, ch1 = in-
  // 0010 = diff, ch2 = in+, ch3 = in-
  // 0100 = diff, ch4 = in+, ch5 = in-

  digitalWrite (SELPIN, LOW); // Select adc

  // first byte
  // first byte will always be B000010xx where xx are the D2 and D1 channel bits 
  byte commandbits = B00001000;
  commandbits |= (channel >> 1);         // high bit of channel

  SPI.transfer(commandbits);       // send out first byte of command bits

  // second byte; Bx0000000; leftmost bit is D0 channel bit
  commandbits = B00000000;
  commandbits |= (channel << 7);        // if D0 is set it will be the leftmost bit now
  b1 = SPI.transfer(commandbits);       // send out second byte of command bits

  // hi byte will have XX0SBBBB
  // set the top 3 don't care bits so it will format nicely
  b1 |= B11100000;
  //Serial.print(b1, BIN); Serial.print(" ");
  sign = b1 & B00010000;
  int hi = b1 & B00001111;

  // read low byte
  b2 = SPI.transfer(b2);              // don't care what we send
  //Serial.print(b2, BIN); Serial.print("\r\n");
  int lo = b2;
  digitalWrite(SELPIN, HIGH); // turn off device

  int reading = hi * 256 + lo;

  if (sign) {
    reading = (4096 - reading) * -1;
  }

  return (reading);
}

User avatar
By RichardS
#79058 Should not be very hard to figure out from here....

R.