mod_dac_max5500.cpp

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/*Beginning of Auto generated code by Atmel studio */
#include <Arduino.h>
/*End of auto generated code by Atmel studio */

#include <Wire.h>
#include <SPI.h>

#include "mod_dac_max5500.h"

#include "config.h" // Fixed pins configuration for this hardware

/* SPI frames for the MAX5500 chip
           16 bits
     MSB --- LSB (MSB first)
|A1 A0  |  C1 C0 | D11 ... D0 |

Commands C1.C0:
 * 0 1: Load DAC, do NOT update DAC output.
 * 1 1: Load DAC, update ALL DAC outputs.

- POLARITY: CPOL=0 (inactive SCK=low level)
- PHASE: CPHA=1 (master changes data on the falling edge of clock)
 ==> SPI_MODE_0 (1?)

*/

void mod_dac_max5500_init()
{
        // start the SPI library:
        SPI.begin();
        digitalWrite(PIN_DAC_MAX5500_CS, HIGH);  // /CS=1
        pinMode(PIN_DAC_MAX5500_CS, OUTPUT);
        // Set all chip outputs to 0V
        mod_dac_max5500_send_spi_word(0x8000);
}

void mod_dac_max5500_send_spi_word(uint16_t tx_word)
{
        // Send HiByte:
        SPI.beginTransaction(SPISettings(8000000, MSBFIRST, SPI_MODE0));

        // nCS -> 0
        digitalWrite(PIN_DAC_MAX5500_CS, LOW);
        delayMicroseconds(1); // Min. 40ns: nCS->0 to SCK

        SPI.transfer16 (tx_word);

        delayMicroseconds(1);

        // nCS -> 1
        digitalWrite(PIN_DAC_MAX5500_CS, HIGH);

        SPI.endTransaction();
}

void mod_dac_max5500_update_single_DAC(uint8_t dac_idx, uint16_t dac_value)
{
        // See word format at the top of this file
        const uint16_t tx_word =
        (((uint16_t)dac_idx) << 14) |
        (((uint16_t)0x03)    << 12) |
        (dac_value & 0x0fff);

        mod_dac_max5500_send_spi_word(tx_word);
}