1 #include "typedefs.h"
 2
 3 #define DAC_DAC_A 0b00
 4 #define DAC_DAC_B 0b01
 5 #define DAC_DAC_C 0b10
 6 #define DAC_DAC_D 0b11
 7
 8 #define DAC_WRITE_SPECIFIC_DO_NOT_UPDATE 0b00
 9 #define DAC_WRITE_SPECIFIC_AND_UPDATE    0b01
10 #define DAC_WRITE_ALL_AND_UPDATE         0b10
11 #define DAC_POWER_DOWN                   0b11
12
13 /* must give the union some name, otherwise compile error in dcc.*/
14 struct DAC124S085_REG_tag{
15     union{
16         uint16_t R;
17         struct{
18             uint16_t reg_addr:2;
19             uint16_t action:2;
20             uint16_t raw_value:12;
21         } B;
22
23     } U;
24 };

void dac_lld_update(uint8_t which_out, uint8_t which_action, uint16_t voltage_in_mv)
{static struct DAC124S085_REG_tag  dac_spi_last_command;

uint16_t tmp16;
      uint32_t tmp32;
      tmp32 = voltage_in_mv*0xFFF;
      tmp16 = tmp32/4096; /* 4096 is the ref voltage. */

    switch(which_out){case DAC_DAC_A://
        dac_spi_command.U.B.reg_addr =  DAC_DAC_A;break;case DAC_DAC_B:dac_spi_command.U.B.reg_addr =  DAC_DAC_B;break;case DAC_DAC_C:dac_spi_command.U.B.reg_addr =  DAC_DAC_C;break;case DAC_DAC_D:dac_spi_command.U.B.reg_addr =  DAC_DAC_D;break;default:return;}switch(which_action){case DAC_WRITE_SPECIFIC_DO_NOT_UPDATE:dac_spi_command.U.B.action =  DAC_WRITE_SPECIFIC_DO_NOT_UPDATE;break;case DAC_WRITE_SPECIFIC_AND_UPDATE:dac_spi_command.U.B.action =  DAC_WRITE_SPECIFIC_AND_UPDATE;break;case DAC_WRITE_ALL_AND_UPDATE:dac_spi_command.U.B.action =  DAC_WRITE_ALL_AND_UPDATE;break;case DAC_POWER_DOWN:dac_spi_command.U.B.action =  DAC_POWER_DOWN;break;default:dac_spi_command.U.B.action =  DAC_WRITE_SPECIFIC_AND_UPDATE;}dac_spi_command.U.B.raw_value =  tmp16;if(dac_spi_command.U.R != dac_spi_last_command.U.R){DSPI_Send(1, 0b00000001,dac_spi_command.U.R); /* semd spi command */}dac_spi_last_command.U.R = dac_spi_command.U.R;
}