rpp/src/drv/dac.c

   1 /* Copyright (C) 2012-2013 Czech Technical University in Prague
   2  *
   3  * Authors:
   4  *     - Michal Horn
   5  *     - Carlos Jenkins <carlos@jenkins.co.cr>
   6  *
   7  * This document contains proprietary information belonging to Czech
   8  * Technical University in Prague. Passing on and copying of this
   9  * document, and communication of its contents is not permitted
  10  * without prior written authorization.
  11  *
  12  * File : dac.c
  13  * Abstract:
  14  *     RPP driver implementation for DAC.
  15  *
  16  * References:
  17  *     None
  18  */
  19
  20
  21 #include "drv/dac.h"
  22
  23 #define DAC_PIN_NUM     4
  24
  25 // See mcp4922.pdf p. 24
  26 // Options:
  27 //   Bit 13: Output Gain Selection bit set = 1x (VOUT = VREF * D/4096)
  28 //   Bit 15: DACA (0) or DACB (1) Selection bit.
  29 #define DAC1_INIT_VAL   (_BV(13)          )
  30 #define DAC2_INIT_VAL   (_BV(13) | _BV(15))
  31 #define DAC3_INIT_VAL   (_BV(13)          )
  32 #define DAC4_INIT_VAL   (_BV(13) | _BV(15))
  33
  34 /**
  35  * Pin status for each DAC pin, the structure of each field is defined
  36  * as spi command structure.
  37  */
  38 uint16_t dac_pin_stat[DAC_PIN_NUM] = {
  39         DAC1_INIT_VAL,
  40         DAC2_INIT_VAL,
  41         DAC3_INIT_VAL,
  42         DAC4_INIT_VAL
  43 };
  44
  45 /**
  46  * Port names for each DAC port, to be easily accessible by indexing
  47  */
  48 const char *dac_port_names[DAC_PIN_NUM] = {
  49         PORT_NAME_DAC1_2,
  50         PORT_NAME_DAC1_2,
  51         PORT_NAME_DAC3_4,
  52         PORT_NAME_DAC3_4
  53 };
  54
  55 /**
  56  * Command for SPI
  57  */
  58 static uint32_t dac_spi_cmd;
  59 /**
  60  * Shadow variable of SPI command
  61  */
  62 static uint32_t dac_spi_cmd_sh;
  63
  64 int drv_dac_spi_transfer(uint8_t pin, boolean_t enabled, uint16_t value)
  65 {
  66         // Check pin range
  67         if (pin >= DAC_PIN_NUM)
  68                 return -1;
  69
  70         // Check value range
  71         if (value > 4095)
  72                 return -2;
  73
  74         // Prepare command
  75         if (enabled)
  76                 bit_set(dac_pin_stat[pin], 12);
  77         else
  78                 bit_clear(dac_pin_stat[pin], 12);
  79
  80         dac_pin_stat[pin] = dac_pin_stat[pin] & 0xF000;
  81         dac_pin_stat[pin] |= (value & 0xFFF);
  82
  83         uint32_t commands[2];
  84
  85         // Warning!!! Can be "optimized" by compiler
  86         dac_spi_cmd = dac_pin_stat[pin];
  87         dac_spi_cmd_sh = dac_spi_cmd;
  88         //--
  89         port_desc_t *desc;
  90         desc = hal_port_get_dsc(dac_port_names[pin], -1);
  91         commands[0] = (dac_spi_cmd_sh & 0xFF00) >> 8;
  92         commands[1] = (dac_spi_cmd_sh & 0xFF);
  93
  94         return desc->port_setfnc_ptr(desc->config, desc->numValues, commands);
  95 }