rpp/src/drv/dac.c

   1 /* Copyright (C) 2012-2015 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
  26 /**
  27  * Pin status for each DAC pin, the structure of each field is defined
  28  * as spi command structure.
  29  *
  30  * See mcp4922.pdf p. 24
  31  * Options:
  32  *   Bit 13: Output Gain Selection bit set = 1x (VOUT = VREF * D/4096)
  33  *   Bit 15: DACA (0) or DACB (1) Selection bit.
  34  *
  35  */
  36 static uint16_t dac_pin_status[DAC_PIN_NUM] = {
  37         (_BV(13)          ),
  38         (_BV(13) | _BV(15)),
  39         (_BV(13)          ),
  40         (_BV(13) | _BV(15))
  41 };
  42
  43 /**
  44  * Port names for each DAC port, to be easily accessible by indexing
  45  */
  46 const char *dac_port_names[DAC_PIN_NUM] = {
  47         DIO_PORT_NAME_DAC1_2,
  48         DIO_PORT_NAME_DAC1_2,
  49         DIO_PORT_NAME_DAC3_4,
  50         DIO_PORT_NAME_DAC3_4
  51 };
  52
  53 /**
  54  * Command for SPI
  55  */
  56 static uint32_t dac_spi_cmd;
  57 /**
  58  * Shadow variable of SPI command
  59  */
  60 static uint32_t dac_spi_cmd_sh;
  61
  62 int drv_dac_spi_transfer(uint8_t pin, boolean_t enabled, uint16_t value)
  63 {
  64         // Check pin range
  65         if (pin >= DAC_PIN_NUM)
  66                 return -1;
  67
  68         // Check value range
  69         if (value > 4095)
  70                 return -2;
  71
  72         // Prepare command
  73         if (enabled)
  74                 bit_set(dac_pin_status[pin], 12);
  75         else
  76                 bit_clear(dac_pin_status[pin], 12);
  77
  78         dac_pin_status[pin] = dac_pin_status[pin] & 0xF000;
  79         dac_pin_status[pin] |= (value & 0xFFF);
  80
  81         uint32_t commands[2];
  82
  83         // Warning!!! Can be "optimized" by compiler
  84         dac_spi_cmd = dac_pin_status[pin];
  85         dac_spi_cmd_sh = dac_spi_cmd;
  86         //--
  87         dio_port_desc_t *desc;
  88         desc = dio_port_get_dsc(dac_port_names[pin], -1);
  89         commands[0] = (dac_spi_cmd_sh & 0xFF00) >> 8;
  90         commands[1] = (dac_spi_cmd_sh & 0xFF);
  91
  92         return desc->port_setfnc_ptr(desc->config, desc->numValues, commands);
  93 }