path: root/src/drivers/batt_smbus/batt_smbus.cpp

/****************************************************************************
 *
 *   Copyright (C) 2012, 2013 PX4 Development Team. All rights reserved.
 *   Author: Randy Mackay <rmackay9@yahoo.com>
 *
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 * 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.
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 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
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 *    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
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/**
 * @file batt_smbus.cpp
 *
 * Driver for a battery monitor connected via SMBus (I2C).
 *
 */

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <sched.h>
#include <semaphore.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <errno.h>
#include <stdio.h>
#include <math.h>
#include <unistd.h>
#include <ctype.h>

#include <nuttx/arch.h>
#include <nuttx/wqueue.h>
#include <nuttx/clock.h>

#include <board_config.h>

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

#include <uORB/uORB.h>
#include <uORB/topics/subsystem_info.h>
#include <uORB/topics/battery_status.h>

#include <float.h>

#include <drivers/device/i2c.h>
#include <drivers/drv_hrt.h>
#include <drivers/drv_batt_smbus.h>
#include <drivers/device/ringbuffer.h>

#define BATT_SMBUS_ADDR_MIN				0x08	/* lowest possible address */
#define BATT_SMBUS_ADDR_MAX				0x7F	/* highest possible address */

#define BATT_SMBUS_I2C_BUS				PX4_I2C_BUS_EXPANSION
#define BATT_SMBUS_ADDR					0x0B	/* I2C address */
#define BATT_SMBUS_TEMP					0x08	/* temperature register */
#define BATT_SMBUS_VOLTAGE				0x09	/* voltage register */
#define BATT_SMBUS_DESIGN_CAPACITY		0x18	/* design capacity register */
#define BATT_SMBUS_DESIGN_VOLTAGE		0x19	/* design voltage register */
#define BATT_SMBUS_SERIALNUM			0x1c	/* serial number register */
#define BATT_SMBUS_MANUFACTURE_NAME     0x20    /* manufacturer name */
#define BATT_SMBUS_MANUFACTURE_INFO		0x25	/* cell voltage register */
#define BATT_SMBUS_CURRENT				0x2a	/* current register */
#define BATT_SMBUS_MEASUREMENT_INTERVAL_MS	(1000000 / 10)	/* time in microseconds, measure at 10hz */

#define BATT_SMBUS_PEC_POLYNOMIAL		0x07	/* Polynomial for calculating PEC */

#ifndef CONFIG_SCHED_WORKQUEUE
# error This requires CONFIG_SCHED_WORKQUEUE.
#endif

class BATT_SMBUS : public device::I2C
{
public:
	BATT_SMBUS(int bus = PX4_I2C_BUS_EXPANSION, uint16_t batt_smbus_addr = BATT_SMBUS_ADDR);
	virtual ~BATT_SMBUS();

	virtual int		init();
	virtual int		test();
	int				search();		/* search all possible slave addresses for a smart battery */

protected:
	virtual int		probe();		// check if the device can be contacted

private:

	// start periodic reads from the battery
	void			start();

	// stop periodic reads from the battery
	void			stop();

	// static function that is called by worker queue
	static void		cycle_trampoline(void *arg);

	// perform a read from the battery
	void			cycle();

	// read_reg - read a word from specified register
	int				read_reg(uint8_t reg, uint16_t &val);

	// read_block - returns number of characters read if successful, zero if unsuccessful
	uint8_t			read_block(uint8_t reg, uint8_t* data, uint8_t max_len, bool append_zero);

	// get_PEC - calculate PEC for a read or write from the battery
	//	buff is the data that was read or will be written
	uint8_t			get_PEC(uint8_t cmd, bool reading, const uint8_t buff[], uint8_t len) const;

	// internal variables
	work_s			_work;			// work queue for scheduling reads
	RingBuffer		*_reports;		// buffer of recorded voltages, currents
	struct battery_status_s _last_report;	// last published report, used for test()
	orb_advert_t	_batt_topic;
	orb_id_t		_batt_orb_id;
};

/* for now, we only support one BATT_SMBUS */
namespace
{
BATT_SMBUS *g_batt_smbus;
}

void batt_smbus_usage();

extern "C" __EXPORT int batt_smbus_main(int argc, char *argv[]);

// constructor
BATT_SMBUS::BATT_SMBUS(int bus, uint16_t batt_smbus_addr) :
	I2C("batt_smbus", BATT_SMBUS_DEVICE_PATH, bus, batt_smbus_addr, 400000),
	_work{},
	_reports(nullptr),
	_batt_topic(-1),
	_batt_orb_id(nullptr)
{
	// work_cancel in the dtor will explode if we don't do this...
	memset(&_work, 0, sizeof(_work));
}

// destructor
BATT_SMBUS::~BATT_SMBUS()
{
	/* make sure we are truly inactive */
	stop();

	if (_reports != nullptr) {
		delete _reports;
	}
}

int
BATT_SMBUS::init()
{
	int ret = ENOTTY;

	// attempt to initialise I2C bus
	ret = I2C::init();

	if (ret != OK) {
		errx(1,"failed to init I2C");
		return ret;
	} else {
		/* allocate basic report buffers */
		_reports = new RingBuffer(2, sizeof(struct battery_status_s));
		if (_reports == nullptr) {
			ret = ENOTTY;
		} else {
			// start work queue
			start();
		}
	}

	// init orb id
	_batt_orb_id = ORB_ID(battery_status);

	return ret;
}

int
BATT_SMBUS::test()
{
	int sub = orb_subscribe(ORB_ID(battery_status));
	bool updated = false;
	struct battery_status_s status;
	uint64_t start_time = hrt_absolute_time();

	// loop for 5 seconds
	while ((hrt_absolute_time() - start_time) < 5000000) {

		// display new info that has arrived from the orb
		orb_check(sub, &updated);
		if (updated) {
			if (orb_copy(ORB_ID(battery_status), sub, &status) == OK) {
				warnx("V=%4.2f C=%4.2f", status.voltage_v, status.current_a);
			}
		}

		// sleep for 0.05 seconds
		usleep(50000);
	}

	return OK;
}

/* search all possible slave addresses for a smart battery */
int
BATT_SMBUS::search()
{
	bool found_slave = false;
	uint16_t tmp;

	// search through all valid SMBus addresses
	for (uint8_t i=BATT_SMBUS_ADDR_MIN; i<=BATT_SMBUS_ADDR_MAX; i++) {
		set_address(i);
		if (read_reg(BATT_SMBUS_VOLTAGE, tmp) == OK) {
			warnx("battery found at 0x%x",(int)i);
			found_slave = true;
		}
		// short sleep
		usleep(1);
	}

	// display completion message
	if (found_slave) {
		warnx("Done.");
	} else {
		warnx("No smart batteries found.");
	}

	return OK;
}

int
BATT_SMBUS::probe()
{
	// always return OK to ensure device starts
	return OK;
}

// start periodic reads from the battery
void
BATT_SMBUS::start()
{
	/* reset the report ring and state machine */
	_reports->flush();

	/* schedule a cycle to start things */
	work_queue(HPWORK, &_work, (worker_t)&BATT_SMBUS::cycle_trampoline, this, 1);
}

// stop periodic reads from the battery
void
BATT_SMBUS::stop()
{
	work_cancel(HPWORK, &_work);
}

// static function that is called by worker queue
void
BATT_SMBUS::cycle_trampoline(void *arg)
{
	BATT_SMBUS *dev = (BATT_SMBUS *)arg;

	dev->cycle();
}

// perform a read from the battery
void
BATT_SMBUS::cycle()
{
	// read data from sensor
	struct battery_status_s new_report;

	// set time of reading
	new_report.timestamp = hrt_absolute_time();

	// read voltage
	uint16_t tmp;
	if (read_reg(BATT_SMBUS_VOLTAGE, tmp) == OK) {
		// initialise new_report
		memset(&new_report, 0, sizeof(new_report));

		// convert millivolts to volts
		new_report.voltage_v = ((float)tmp) / 1000.0f;

		// read current
		usleep(1);
		uint8_t buff[4];
		if (read_block(BATT_SMBUS_CURRENT, buff, 4, false) == 4) {
			new_report.current_a = (float)((int32_t)((uint32_t)buff[3]<<24 | (uint32_t)buff[2]<<16 | (uint32_t)buff[1]<<8 | (uint32_t)buff[0])) / 1000.0f;
		}

		// publish to orb
		if (_batt_topic != -1) {
			orb_publish(_batt_orb_id, _batt_topic, &new_report);
		} else {
			_batt_topic = orb_advertise(_batt_orb_id, &new_report);
			if (_batt_topic < 0) {
				errx(1, "ADVERT FAIL");
			}
		}

		// copy report for test()
		_last_report = new_report;

		/* post a report to the ring */
		_reports->force(&new_report);

		/* notify anyone waiting for data */
		poll_notify(POLLIN);
	}

	/* schedule a fresh cycle call when the measurement is done */
	work_queue(HPWORK, &_work, (worker_t)&BATT_SMBUS::cycle_trampoline, this, USEC2TICK(BATT_SMBUS_MEASUREMENT_INTERVAL_MS));
}

int
BATT_SMBUS::read_reg(uint8_t reg, uint16_t &val)
{
	uint8_t buff[3];	// 2 bytes of data + PEC

	// read from register
	int ret = transfer(&reg, 1, buff, 3);
	if (ret == OK) {
		// check PEC
		uint8_t pec = get_PEC(reg, true, buff, 2);
		if (pec == buff[2]) {
			val = (uint16_t)buff[1] << 8 | (uint16_t)buff[0];
		} else {
			ret = ENOTTY;
		}
	}

	// return success or failure
	return ret;
}

// read_block - returns number of characters read if successful, zero if unsuccessful
uint8_t BATT_SMBUS::read_block(uint8_t reg, uint8_t* data, uint8_t max_len, bool append_zero)
{
	uint8_t buff[max_len+2];    // buffer to hold results

	usleep(1);

	// read bytes including PEC
	int ret = transfer(&reg, 1, buff, max_len+2);

	// return zero on failure
	if (ret != OK) {
		return 0;
	}

	// get length
	uint8_t bufflen = buff[0];

	// sanity check length returned by smbus
	if (bufflen == 0 || bufflen > max_len) {
		return 0;
	}

	// check PEC
	uint8_t pec = get_PEC(reg, true, buff, bufflen+1);
	if (pec != buff[bufflen+1]) {
		// debug
		warnx("CurrPEC:%x vs MyPec:%x",(int)buff[bufflen+1],(int)pec);
		return 0;
	} else {
		warnx("CurPEC ok: %x",(int)pec);
	}

	// copy data
	memcpy(data, &buff[1], bufflen);

	// optionally add zero to end
	if (append_zero) {
		data[bufflen] = '\0';
	}

	// return success
	return bufflen;
}

// get_PEC - calculate PEC for a read or write from the battery
//	buff is the data that was read or will be written
uint8_t BATT_SMBUS::get_PEC(uint8_t cmd, bool reading, const uint8_t buff[], uint8_t len) const
{
	// exit immediately if no data
	if (len <= 0) {
		return 0;
	}

	// prepare temp buffer for calcing crc
	uint8_t tmp_buff[len+3];
	tmp_buff[0] = (uint8_t)get_address() << 1;
	tmp_buff[1] = cmd;
	tmp_buff[2] = tmp_buff[0] | (uint8_t)reading;
	memcpy(&tmp_buff[3],buff,len);

	// initialise crc to zero
	uint8_t crc = 0;
	uint8_t shift_reg = 0;
	bool do_invert;

	// for each byte in the stream
	for (uint8_t i=0; i<sizeof(tmp_buff); i++) {
		// load next data byte into the shift register
		shift_reg = tmp_buff[i];
		// for each bit in the current byte
		for (uint8_t j=0; j<8; j++) {
			do_invert = (crc ^ shift_reg) & 0x80;
			crc <<= 1;
			shift_reg <<= 1;
			if (do_invert) {
				crc ^= BATT_SMBUS_PEC_POLYNOMIAL;
			}
		}
	}

	// return result
	return crc;
}

///////////////////////// shell functions ///////////////////////

void
batt_smbus_usage()
{
	warnx("missing command: try 'start', 'test', 'stop', 'search'");
	warnx("options:");
		warnx("    -b i2cbus (%d)", BATT_SMBUS_I2C_BUS);
		warnx("    -a addr (0x%x)", BATT_SMBUS_ADDR);
}

int
batt_smbus_main(int argc, char *argv[])
{
	int i2cdevice = BATT_SMBUS_I2C_BUS;
	int batt_smbusadr = BATT_SMBUS_ADDR; /* 7bit */

	int ch;

	/* jump over start/off/etc and look at options first */
	while ((ch = getopt(argc, argv, "a:b:")) != EOF) {
		switch (ch) {
		case 'a':
			batt_smbusadr = strtol(optarg, NULL, 0);
			break;

		case 'b':
			i2cdevice = strtol(optarg, NULL, 0);
			break;

		default:
			batt_smbus_usage();
			exit(0);
		}
	}

	if (optind >= argc) {
		batt_smbus_usage();
		exit(1);
	}

	const char *verb = argv[optind];

	if (!strcmp(verb, "start")) {
		if (g_batt_smbus != nullptr) {
			errx(1, "already started");
		} else {
			// create new global object
			g_batt_smbus = new BATT_SMBUS(i2cdevice, batt_smbusadr);

			if (g_batt_smbus == nullptr) {
				errx(1, "new failed");
			}

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

		exit(0);
	}

	/* need the driver past this point */
	if (g_batt_smbus == nullptr) {
		warnx("not started");
		batt_smbus_usage();
		exit(1);
	}

	if (!strcmp(verb, "test")) {
		g_batt_smbus->test();
		exit(0);
	}

	if (!strcmp(verb, "stop")) {
		delete g_batt_smbus;
		g_batt_smbus = nullptr;
		exit(0);
	}

	if (!strcmp(verb, "search")) {
		g_batt_smbus->search();
		exit(0);
	}

	batt_smbus_usage();
	exit(0);
}