mcp4012_x.c

#include "mcp4012_x.h"
#include "boards.h"
#include "nrf.h"
#include "hal_nop_delay.h"
#include "hal_gpio.h"
#include "string.h"
#include "stdint.h"
#include "nrf_assert.h"

#ifndef SPIM_ENABLE_ENABLE_Enabled
#error "The SoC does not have the SPIM peripheral needed for this module"
#endif

#define SPIM_ID CONCAT_2(NRF_SPIM,SPIM_USED_MCP4012_DRIVER)

static void simple_spi_init();

static void simple_spi_transmit(uint8_t *data, uint32_t len);

#define BUFFER_SIZE 16

#define NO_OF_STEPS 64

#define SIZE_OF_WORD (NO_OF_STEPS/BUFFER_SIZE)

#define ALL_AA 0xAA

#define ALL_00 0x00

static uint8_t data_to_be_sent[BUFFER_SIZE];
static uint32_t UD_bar;
static uint32_t CS_bar;
static uint32_t SCK_pin;

void mcp4012_init(uint32_t CS_bar_pin_no, uint32_t UD_bar_pin_no, uint32_t SCK_pin_no)
{
  hal_gpio_cfg_output(CS_bar_pin_no, 1);
  hal_gpio_cfg_output(UD_bar_pin_no, 1);
  hal_gpio_cfg_output(SCK_pin_no, 1);
  UD_bar = UD_bar_pin_no;
  CS_bar = CS_bar_pin_no;
  SCK_pin = SCK_pin_no;
}

void mcp4012_set_value(uint32_t value_sent_by_user)
{
    ASSERT(value_sent_by_user < NO_OF_STEPS);
  uint32_t i =0;
  uint32_t word_no = 0;
  uint32_t last_seq = 0;
  uint32_t last_word_no = 0;
  uint32_t wiper_value = 0;
  /*Set value of all the bytes in data_to_be_sent as 0b10101010*/
  memset(data_to_be_sent, ALL_AA, BUFFER_SIZE);

  /* Part to set wiper value to maximum */
  hal_gpio_pin_set(CS_bar);
  hal_nop_delay_us(1);
  hal_gpio_pin_set(UD_bar);
  hal_nop_delay_us(1);      //T(LCU)
  hal_gpio_pin_clear(CS_bar);
  hal_nop_delay_us(1);      //T(LCUF)
  hal_gpio_pin_clear(UD_bar);
  hal_nop_delay_us(2);      //T(LCUR)-T(LCUF)
  simple_spi_transmit(data_to_be_sent, BUFFER_SIZE);
  hal_gpio_pin_set(CS_bar);

  /* As we are setting wiper value to maximum, to set value to different value
     we need to decrease it by (maximum_wiper_value - value_sent_by_user) */
  wiper_value = NO_OF_STEPS - value_sent_by_user;
  word_no = wiper_value/SIZE_OF_WORD;
  last_seq = wiper_value % SIZE_OF_WORD;
  last_word_no = word_no+1;

    /* To set data_to_be_sent[0 ... (byte-1)] as 0b10101010 */
  memset(data_to_be_sent, ALL_AA, word_no);
  /* To set data_to_be_sent[byte_no ... 15] as 0b0000000 */
  memset(&data_to_be_sent[word_no], ALL_00, (BUFFER_SIZE-word_no));
  /* Loop to set value for data_to_be_sent[byte_no] */
  for(i = 0; i < last_seq; i++)
  {
    data_to_be_sent[word_no] = 0x80 | data_to_be_sent[word_no] >> 2;
  }

  /* Part to decrease wiper value by (maximum - wiper_value_given_by_user) */
  hal_gpio_pin_set(UD_bar);
  hal_nop_delay_us(1);
  hal_gpio_pin_set(CS_bar);
  hal_gpio_pin_clear(UD_bar);
  hal_nop_delay_us(1);      //T(LCU)
  hal_gpio_pin_clear(CS_bar);
  hal_nop_delay_us(2);      //T(LCUR)
  simple_spi_transmit(data_to_be_sent, last_word_no);
  hal_gpio_pin_set(CS_bar);
}


static void simple_spi_init()
{
  SPIM_ID->TASKS_SUSPEND  = 1;
  SPIM_ID->TASKS_STOP = 1;
    SPIM_ID->PSEL.MOSI = UD_bar | (0 << 31);//UD_bar selected as MOSI
  SPIM_ID->PSEL.SCK = SCK_pin | (0 << 31);
  SPIM_ID->CONFIG = (SPIM_CONFIG_ORDER_MsbFirst << SPIM_CONFIG_ORDER_Pos)
            |(SPIM_CONFIG_CPHA_Trailing << SPIM_CONFIG_CPHA_Pos)
            |(SPIM_CONFIG_CPOL_ActiveHigh << SPIM_CONFIG_CPOL_Pos);
  //Data line frequency will be 500 kHz
  SPIM_ID->FREQUENCY = SPIM_FREQUENCY_FREQUENCY_M1 << SPIM_FREQUENCY_FREQUENCY_Pos;
  SPIM_ID->TXD.LIST = 1 << 0;
}

static void simple_spi_transmit(uint8_t *data, uint32_t len)
{
  simple_spi_init();
  SPIM_ID->TXD.PTR = (uint32_t ) data;
  SPIM_ID->TXD.MAXCNT = len;
  SPIM_ID->ENABLE = SPIM_ENABLE_ENABLE_Enabled << SPIM_ENABLE_ENABLE_Pos;
  SPIM_ID->TASKS_START = 0x01;
  while(!(SPIM_ID->EVENTS_ENDTX));
  SPIM_ID->EVENTS_ENDTX = 0;
  SPIM_ID->ENABLE = SPIM_ENABLE_ENABLE_Disabled << SPIM_ENABLE_ENABLE_Pos;
  SPIM_ID->TASKS_STOP = 0x01;
}