NB2A DAC

NB2A DAC Files

NB2A DAC Example

The NB2A has a TLV5618 dual 12-bit DAC with a 1.24V reference. The DAC library contains the functions to initialize the DAC object, set the output voltage. The example program initializes the DAC and sets channel A to 0.75V, B to 0.5V.

When initializing the DAC object you need to define which pin number is connected to the CS pin. The example code below creates a DAC object using the default pin assignment for the NB2A.


// the load pin is attached to pin 10 (PB2)
// and the latch pin is attached to pin 9 (PB1)
// the spi port is attached to spi0

#define DAC_CS_PIN  4 // Sanguino Pin Number (ATmega644P PB4)

LED_debug led;

DAC_TLV5618 dac  = DAC_TLV5618(DAC_CS_PIN);

NB2A DAC Example

#include <avr/interrupt.h>    
#include <avr/io.h>  

#include <SPI.h>
#include <DAC.h>
#include <LED_debug.h>

#define ON  HIGH
#define OFF LOW

// DAC demo program for an NB2A.
// The DAC is a TI TLV5618 with a 1.225V reference.

// the chip select pin is attached to pin 5 (PB4)

#define DAC_CS_PIN     4  //PB4
#define SPI_TIMEOUT    10 // mS

LED_debug led(15);

SPI spi = SPI(SPI_TIMEOUT, NB2A_MOSI_PIN, NB2A_MISO_PIN, NB2A_SCK_PIN);
DAC_TLV5618 dac  = DAC_TLV5618(DAC_CS_PIN);

void setup() {

  // 
  // The NB2A uses a 12MHz XTAL
  // The Sanguino uses a 16MHz XTAL.
  // If f_cpu frequency is set to 16000000L in your
  // boards.txt file then correct for the 
  // difference in XTAL frequency
  // using one of the values below --
  // 
  // 12800 = (16/12) * 9600
  // 25600 = (16/12) * 19200
  //

  Serial.begin(9600); // f_cpu set to 12000000L in boards.txt

  // Setup the SPI control register (SPCR)
  // and the status register (SPSR)

  // Page 169 ATmega644P Datasheet Rev 8011L-AVR-02/09

  // SPIE = 0  =0 SPI INT disabled,   =1 enabled
  // SPE  = 1  =0 SPI disabled,       =1 enabled     
  // DORD = 0  =0 MSB First,          =1 LSB First
  // MSTR = 1  =0 Slave,              =1 Master mode
  // CPOL = 1  =0 SCK high when idle, =1 SCK low when idle,
  // CPHA = 1  =0 Sample on leading edge, =1 falling edge
  // SPR1, SPR2 = 0 fosc/4 (= 1 fosc/16)
  //                       (= 2 fosc/64)
  //                       (= 3 fosc/128)

  // SPSR is read only except for the double speed bit

  // SPI2X = 1 double speed

  spi.init(((1<<SPE) | (1<<MSTR) | (0<<CPHA) | (1<<CPOL)), (1<<SPI2X));

}

void loop() {

  // DACA is U21 pin 4
  // DACB is U21 pin 7
  
  dac.set_voltage(DAC_WRITE_B_AND_BUFFER, 1);
  dac.set_voltage(DAC_WRITE_A_UPDATE_B, 1.75);
   
  while(1) {
    led.blink(2);
    delay(1000);
  }

}