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/****************************************************************************
*
* Copyright (C) 2012 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @file adc.c
*
* Simple ADC support for PX4IO on STM32.
*/
#include <nuttx/config.h>
#include <stdint.h>
#include <nuttx/arch.h>
#include <arch/stm32/chip.h>
#include <stm32.h>
#include <drivers/drv_hrt.h>
#include <systemlib/perf_counter.h>
#define DEBUG
#include "px4io.h"
/*
* Register accessors.
* For now, no reason not to just use ADC1.
*/
#define REG(_reg) (*(volatile uint32_t *)(STM32_ADC1_BASE + _reg))
#define rSR REG(STM32_ADC_SR_OFFSET)
#define rCR1 REG(STM32_ADC_CR1_OFFSET)
#define rCR2 REG(STM32_ADC_CR2_OFFSET)
#define rSMPR1 REG(STM32_ADC_SMPR1_OFFSET)
#define rSMPR2 REG(STM32_ADC_SMPR2_OFFSET)
#define rJOFR1 REG(STM32_ADC_JOFR1_OFFSET)
#define rJOFR2 REG(STM32_ADC_JOFR2_OFFSET)
#define rJOFR3 REG(STM32_ADC_JOFR3_OFFSET)
#define rJOFR4 REG(STM32_ADC_JOFR4_OFFSET)
#define rHTR REG(STM32_ADC_HTR_OFFSET)
#define rLTR REG(STM32_ADC_LTR_OFFSET)
#define rSQR1 REG(STM32_ADC_SQR1_OFFSET)
#define rSQR2 REG(STM32_ADC_SQR2_OFFSET)
#define rSQR3 REG(STM32_ADC_SQR3_OFFSET)
#define rJSQR REG(STM32_ADC_JSQR_OFFSET)
#define rJDR1 REG(STM32_ADC_JDR1_OFFSET)
#define rJDR2 REG(STM32_ADC_JDR2_OFFSET)
#define rJDR3 REG(STM32_ADC_JDR3_OFFSET)
#define rJDR4 REG(STM32_ADC_JDR4_OFFSET)
#define rDR REG(STM32_ADC_DR_OFFSET)
perf_counter_t adc_perf;
int
adc_init(void)
{
adc_perf = perf_alloc(PC_ELAPSED, "adc");
/* put the ADC into power-down mode */
rCR2 &= ~ADC_CR2_ADON;
up_udelay(10);
/* bring the ADC out of power-down mode */
rCR2 |= ADC_CR2_ADON;
up_udelay(10);
/* do calibration if supported */
#ifdef ADC_CR2_CAL
rCR2 |= ADC_CR2_RSTCAL;
up_udelay(1);
if (rCR2 & ADC_CR2_RSTCAL)
return -1;
rCR2 |= ADC_CR2_CAL;
up_udelay(100);
if (rCR2 & ADC_CR2_CAL)
return -1;
#endif
/*
* Configure sampling time.
*
* For electrical protection reasons, we want to be able to have
* 10K in series with ADC inputs that leave the board. At 12MHz this
* means we need 28.5 cycles of sampling time (per table 43 in the
* datasheet).
*/
rSMPR1 = 0b00000000011011011011011011011011;
rSMPR2 = 0b00011011011011011011011011011011;
rCR2 |= ADC_CR2_TSVREFE; /* enable the temperature sensor / Vrefint channel */
/* configure for a single-channel sequence */
rSQR1 = 0;
rSQR2 = 0;
rSQR3 = 0; /* will be updated with the channel at conversion time */
return 0;
}
/*
return one measurement, or 0xffff on error
*/
uint16_t
adc_measure(unsigned channel)
{
perf_begin(adc_perf);
/* clear any previous EOC */
rSR = 0;
(void)rDR;
/* run a single conversion right now - should take about 60 cycles (a few microseconds) max */
rSQR3 = channel;
rCR2 |= ADC_CR2_ADON;
/* wait for the conversion to complete */
hrt_abstime now = hrt_absolute_time();
while (!(rSR & ADC_SR_EOC)) {
/* never spin forever - this will give a bogus result though */
if (hrt_elapsed_time(&now) > 100) {
perf_end(adc_perf);
return 0xffff;
}
}
/* read the result and clear EOC */
uint16_t result = rDR;
rSR = 0;
perf_end(adc_perf);
return result;
}
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