px4_autopilot/apps/drivers/stm32/adc/adc.cpp

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/**
 * @file adc.cpp
 *
 * Driver for the STM32 ADC.
 *
 * This is a low-rate driver, designed for sampling things like voltages
 * and so forth. It avoids the gross complexity of the NuttX ADC driver.
 */

#include <nuttx/config.h>
#include <drivers/device/device.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>

#include <arch/board/board.h>
#include <drivers/drv_hrt.h>
#include <drivers/drv_adc.h>

#include <arch/stm32/chip.h>
#include <stm32_internal.h>
#include <stm32_gpio.h>

#include <systemlib/err.h>
#include <systemlib/perf_counter.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)

#ifdef STM32_ADC_CCR
# define rCCR		REG(STM32_ADC_CCR_OFFSET)
#endif

class ADC : public device::CDev
{
public:
	ADC(uint32_t channels);
	~ADC();

	virtual int		init();

	virtual int		ioctl(file *filp, int cmd, unsigned long arg);
	virtual ssize_t		read(file *filp, char *buffer, size_t len);

protected:
	virtual int		open_first(struct file *filp);
	virtual int		close_last(struct file *filp);

private:
	static const hrt_abstime _tickrate = 10000;	/**< 100Hz base rate */
	
	hrt_call		_call;
	perf_counter_t		_sample_perf;

	unsigned		_channel_count;
	adc_msg_s		*_samples;		/**< sample buffer */

	/** work trampoline */
	static void		_tick_trampoline(void *arg);

	/** worker function */
	void			_tick();

	/**
	 * Sample a single channel and return the measured value.
	 *
	 * @param channel		The channel to sample.
	 * @return			The sampled value, or 0xffff if
	 *				sampling failed.
	 */
	uint16_t		_sample(unsigned channel);

};

ADC::ADC(uint32_t channels) :
	CDev("adc", ADC_DEVICE_PATH),
	_sample_perf(perf_alloc(PC_ELAPSED, "ADC samples")),
	_channel_count(0),
	_samples(nullptr)
{
	_debug_enabled = true;

	/* always enable the temperature sensor */
	channels |= 1 << 16;

	/* allocate the sample array */
	for (unsigned i = 0; i < 32; i++) {
		if (channels & (1 << i)) {
			_channel_count++;
		}
	}
	_samples = new adc_msg_s[_channel_count];

	/* prefill the channel numbers in the sample array */
	if (_samples != nullptr) {
		unsigned index = 0;
		for (unsigned i = 0; i < 32; i++) {
			if (channels & (1 << i)) {
				_samples[index].am_channel = i;
				_samples[index].am_data = 0;
				index++;
			}
		}
	}
}

ADC::~ADC()
{
	if (_samples != nullptr)
		delete _samples;
}

int
ADC::init()
{
	/* do calibration if supported */
#ifdef ADC_CR2_CAL
	rCR2 |= ADC_CR2_CAL;
	usleep(100);
	if (rCR2 & ADC_CR2_CAL)
		return -1;
#endif

	/* arbitrarily configure all channels for 55 cycle sample time */
	rSMPR1 = 0b00000011011011011011011011011011;
	rSMPR2 = 0b00011011011011011011011011011011;

	/* XXX for F2/4, might want to select 12-bit mode? */
	rCR1 = 0;

	/* enable the temperature sensor / Vrefint channel if supported*/
	rCR2 = 
#ifdef ADC_CR2_TSVREFE
		/* enable the temperature sensor in CR2 */
		ADC_CR2_TSVREFE |
#endif
		0;

#ifdef ADC_CCR_TSVREFE
	/* enable temperature sensor in CCR */
	rCCR = ADC_CCR_TSVREFE;
#endif

	/* configure for a single-channel sequence */
	rSQR1 = 0;
	rSQR2 = 0;
	rSQR3 = 0;	/* will be updated with the channel each tick */ 

	/* power-cycle the ADC and turn it on */
	rCR2 &= ~ADC_CR2_ADON;
	usleep(10);
	rCR2 |= ADC_CR2_ADON;
	usleep(10);
	rCR2 |= ADC_CR2_ADON;
	usleep(10);

	/* kick off a sample and wait for it to complete */
	hrt_abstime now = hrt_absolute_time();
	rCR2 |= ADC_CR2_SWSTART;
	while (!(rSR & ADC_SR_EOC)) {

		/* don't wait for more than 500us, since that means something broke - should reset here if we see this */
		if ((hrt_absolute_time() - now) > 500) {
			log("sample timeout");
			return -1;
			return 0xffff;
		}
	}


	debug("init done");

	/* create the device node */
	return CDev::init();
}

int
ADC::ioctl(file *filp, int cmd, unsigned long arg)
{
	return -ENOTTY;
}

ssize_t
ADC::read(file *filp, char *buffer, size_t len)
{
	const size_t maxsize = sizeof(adc_msg_s) * _channel_count;

	if (len > maxsize)
		len = maxsize;

	/* block interrupts while copying samples to avoid racing with an update */
	irqstate_t flags = irqsave();
	memcpy(buffer, _samples, len);
	irqrestore(flags);

	return len;
}

int
ADC::open_first(struct file *filp)
{
	/* get fresh data */
	_tick();

	/* and schedule regular updates */
	hrt_call_every(&_call, _tickrate, _tickrate, _tick_trampoline, this);

	return 0;
}

int
ADC::close_last(struct file *filp)
{
	hrt_cancel(&_call);
	return 0;
}

void
ADC::_tick_trampoline(void *arg)
{
	((ADC *)arg)->_tick();
}

void
ADC::_tick()
{
	/* scan the channel set and sample each */
	for (unsigned i = 0; i < _channel_count; i++)
		_samples[i].am_data = _sample(_samples[i].am_channel);
}

uint16_t
ADC::_sample(unsigned channel)
{
	perf_begin(_sample_perf);

	/* clear any previous EOC */
	if (rSR & ADC_SR_EOC)
		rSR &= ~ADC_SR_EOC;

	/* run a single conversion right now - should take about 60 cycles (a few microseconds) max */
	rSQR3 = channel;
	rCR2 |= ADC_CR2_SWSTART;

	/* wait for the conversion to complete */
	hrt_abstime now = hrt_absolute_time();
	while (!(rSR & ADC_SR_EOC)) {

		/* don't wait for more than 50us, since that means something broke - should reset here if we see this */
		if ((hrt_absolute_time() - now) > 50) {
			log("sample timeout");
			return 0xffff;
		}
	}

	/* read the result and clear EOC */
	uint16_t result = rDR;

	perf_end(_sample_perf);
	return result;
}

/*
 * Driver 'main' command.
 */
extern "C" __EXPORT int adc_main(int argc, char *argv[]);

namespace
{
ADC	*g_adc;

void
test(void)
{

	int fd = open(ADC_DEVICE_PATH, O_RDONLY);
	if (fd < 0)
		err(1, "can't open ADC device");

	for (unsigned i = 0; i < 50; i++) {
		adc_msg_s data[8];
		ssize_t count = read(fd, data, sizeof(data));

		if (count < 0)
			errx(1, "read error");

		unsigned channels = count / sizeof(data[0]);

		for (unsigned j = 0; j < channels; j++) {
			printf ("%d: %u  ", data[j].am_channel, data[j].am_data);
		}

		printf("\n");
		usleep(500000);
	}

	exit(0);
}
}

int
adc_main(int argc, char *argv[])
{
	if (g_adc == nullptr) {
		/* XXX this hardcodes the default channel set for PX4FMU - should be configurable */
		g_adc = new ADC((1 << 10) | (1 << 11) | (1 << 12) | (1 << 13));

		if (g_adc == nullptr)
			errx(1, "couldn't allocate the ADC driver");

		if (g_adc->init() != OK) {
			delete g_adc;
			errx(1, "ADC init failed");
		}
	}

	if (argc > 1) {
		if (!strcmp(argv[1], "test"))
			test();
	}

	exit(0);
}