dac.c
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/*
* Copyright (C) 2017 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_sam3
* @{
*
* @file
* @brief Low-level DAC driver implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*
* @}
*/
#include "cpu.h"
#include "assert.h"
#include "periph/dac.h"
#define WP_KEY (0x444143)
#define PMC_BIT (1 << (ID_DACC - 32))
#ifndef DAC_STARTUP
#define DAC_STARTUP (DACC_MR_STARTUP_1984)
#endif
#ifndef DAC_REFRESH
#define DAC_REFRESH (DACC_MR_REFRESH(128))
#endif
int8_t dac_init(dac_t line)
{
assert(line < DAC_NUMOF);
/* power on DACC peripheral */
PMC->PMC_PCER1 = PMC_BIT;
/* unlock DACC registers */
DACC->DACC_WPMR = DACC_WPMR_WPKEY(WP_KEY);
/* configure mode register */
DACC->DACC_MR = (DAC_STARTUP | DACC_MR_TAG_EN | DAC_REFRESH);
/* enable the selected channel/line */
DACC->DACC_CHER = (1 << line);
/* set line initially to 0 volts -> this will startup the channel and the
* channel is ready after the defined number of startup cycles
* (DAC_STARTUP) have passed */
dac_set(line, 0);
return 0;
}
void dac_set(dac_t line, uint16_t value)
{
assert(line < DAC_NUMOF);
DACC->DACC_CDR = ((value >> 4) | (line << 12));
}
void dac_poweron(dac_t line)
{
assert(line < DAC_NUMOF);
PMC->PMC_PCER1 = (1 << (ID_DACC - 32));
DACC->DACC_CHER = PMC_BIT;
}
void dac_poweroff(dac_t line)
{
assert(line < DAC_NUMOF);
DACC->DACC_CHDR = (1 << line);
if (!(DACC->DACC_CHSR)) {
PMC->PMC_PCDR1 = PMC_BIT;
}
}