PX4-Autopilot/src/drivers/rc/sbus/RCInput.cpp

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#include "RCInput.hpp"

#include <termios.h>

using namespace time_literals;

RcSbus::RcSbus(const char *device) :
	ModuleParams(nullptr),
	ScheduledWorkItem(MODULE_NAME, px4::serial_port_to_wq(device))
{
	// initialize raw_rc values and count
	for (unsigned i = 0; i < input_rc_s::RC_INPUT_MAX_CHANNELS; i++) {
		_raw_rc_values[i] = UINT16_MAX;
	}

	if (device) {
		strncpy(_device, device, sizeof(_device) - 1);
		_device[sizeof(_device) - 1] = '\0';
	}
}

RcSbus::~RcSbus()
{
	perf_free(_cycle_perf);
	perf_free(_publish_interval_perf);
}

int RcSbus::init()
{
	_rcs_fd = ::open(_device, O_RDWR | O_NONBLOCK);

	// assume SBUS input and immediately switch it to
	// so that if Single wire mode on TX there will be only
	// a short contention
	sbus_config(_rcs_fd, board_rc_singlewire(_device));

	if (_rcs_fd < 0) {
		return -errno;
	}

	if (board_rc_swap_rxtx(_device)) {
#if defined(TIOCSSWAP)
		ioctl(_rcs_fd, TIOCSSWAP, SER_SWAP_ENABLED);
#endif // TIOCSSWAP
	}

#ifdef GPIO_PPM_IN
	// disable CPPM input by mapping it away from the timer capture input
	px4_arch_unconfiggpio(GPIO_PPM_IN);
#endif // GPIO_PPM_IN

	rc_io_invert(false);

	return 0;
}

int RcSbus::task_spawn(int argc, char *argv[])
{
	bool error_flag = false;

	int myoptind = 1;
	int ch;
	const char *myoptarg = nullptr;
	const char *device_name = nullptr;
#if defined(RC_SERIAL_PORT)
	device_name = RC_SERIAL_PORT;
#endif // RC_SERIAL_PORT

	while ((ch = px4_getopt(argc, argv, "d:", &myoptind, &myoptarg)) != EOF) {
		switch (ch) {
		case 'd':
			device_name = myoptarg;
			break;

		case '?':
			error_flag = true;
			break;

		default:
			PX4_WARN("unrecognized flag");
			error_flag = true;
			break;
		}
	}

	if (error_flag) {
		return -1;
	}

	if (device_name && (access(device_name, R_OK | W_OK) == 0)) {
		RcSbus *instance = new RcSbus(device_name);

		if (instance == nullptr) {
			PX4_ERR("alloc failed");
			return PX4_ERROR;
		}

		_object.store(instance);
		_task_id = task_id_is_work_queue;

		instance->ScheduleOnInterval(_current_update_interval);

		return PX4_OK;

	} else {
		if (device_name) {
			PX4_ERR("invalid device (-d) %s", device_name);

		} else {
			PX4_INFO("valid device required");
		}
	}

	return PX4_ERROR;
}

void RcSbus::fill_rc_in(uint16_t raw_rc_count_local,
			uint16_t raw_rc_values_local[input_rc_s::RC_INPUT_MAX_CHANNELS],
			hrt_abstime now, bool frame_drop, bool failsafe,
			unsigned frame_drops, int rssi = -1)
{
	// fill rc_in struct for publishing
	_rc_in.channel_count = raw_rc_count_local;

	if (_rc_in.channel_count > input_rc_s::RC_INPUT_MAX_CHANNELS) {
		_rc_in.channel_count = input_rc_s::RC_INPUT_MAX_CHANNELS;
	}

	unsigned valid_chans = 0;

	for (unsigned i = 0; i < _rc_in.channel_count; i++) {
		_rc_in.values[i] = raw_rc_values_local[i];

		if (raw_rc_values_local[i] != UINT16_MAX) {
			valid_chans++;
		}

		// once filled, reset values back to default
		_raw_rc_values[i] = UINT16_MAX;
	}

	_rc_in.timestamp = now;
	_rc_in.timestamp_last_signal = _rc_in.timestamp;
	_rc_in.rc_ppm_frame_length = 0;

	/* fake rssi if no value was provided */
	if (rssi == -1) {
		if ((_param_rc_rssi_pwm_chan.get() > 0) && (_param_rc_rssi_pwm_chan.get() < _rc_in.channel_count)) {
			const int32_t rssi_pwm_chan = _param_rc_rssi_pwm_chan.get();
			const int32_t rssi_pwm_min = _param_rc_rssi_pwm_min.get();
			const int32_t rssi_pwm_max = _param_rc_rssi_pwm_max.get();

			// get RSSI from input channel
			int rc_rssi = ((_rc_in.values[rssi_pwm_chan - 1] - rssi_pwm_min) * 100) / (rssi_pwm_max - rssi_pwm_min);
			_rc_in.rssi = math::constrain(rc_rssi, 0, 100);

		} else if (_analog_rc_rssi_stable) {
			// set RSSI if analog RSSI input is present
			float rssi_analog = ((_analog_rc_rssi_volt - 0.2f) / 3.0f) * 100.0f;

			if (rssi_analog > 100.0f) {
				rssi_analog = 100.0f;
			}

			if (rssi_analog < 0.0f) {
				rssi_analog = 0.0f;
			}

			_rc_in.rssi = rssi_analog;

		} else {
			_rc_in.rssi = 255;
		}

	} else {
		_rc_in.rssi = rssi;
	}

	if (valid_chans == 0) {
		_rc_in.rssi = 0;
	}

	_rc_in.rc_failsafe = failsafe;
	_rc_in.rc_lost = (valid_chans == 0);
	_rc_in.rc_lost_frame_count = frame_drops;
	_rc_in.rc_total_frame_count = 0;
}

void RcSbus::rc_io_invert(bool invert)
{
	// First check if the board provides a board-specific inversion method (e.g. via GPIO),
	// and if not use an IOCTL
	if (!board_rc_invert_input(_device, invert)) {
#if defined(TIOCSINVERT)

		if (invert) {
			ioctl(_rcs_fd, TIOCSINVERT, SER_INVERT_ENABLED_RX | SER_INVERT_ENABLED_TX);

		} else {
			ioctl(_rcs_fd, TIOCSINVERT, 0);
		}

#endif // TIOCSINVERT
	}
}

void RcSbus::Run()
{
	if (should_exit()) {
		exit_and_cleanup();
		return;
	}

	if (!_initialized) {
		if (init() == PX4_OK) {
			_initialized = true;

		} else {
			PX4_ERR("init failed");
			exit_and_cleanup();
		}

	} else {

		perf_begin(_cycle_perf);

		// Check if parameters have changed
		if (_parameter_update_sub.updated()) {
			// clear update
			parameter_update_s param_update;
			_parameter_update_sub.copy(&param_update);

			updateParams();
		}

		const hrt_abstime cycle_timestamp = hrt_absolute_time();

		bool rc_updated = false;

		// This block scans for a supported serial RC input and locks onto the first one found
		// Scan for 500 msec, then switch protocol
		constexpr hrt_abstime rc_scan_max = 500_ms;

		unsigned frame_drops = 0;

		// TODO: needs work (poll _rcs_fd)
		// int ret = poll(fds, sizeof(fds) / sizeof(fds[0]), 100);
		// then update priority to SCHED_PRIORITY_FAST_DRIVER
		// read all available data from the serial RC input UART

		// read all available data from the serial RC input UART
		int newBytes = ::read(_rcs_fd, &_rcs_buf[0], RC_MAX_BUFFER_SIZE);

		if (newBytes > 0) {
			_bytes_rx += newBytes;
		}

		const bool rc_scan_locked = _rc_scan_locked;

		if (_rc_scan_begin == 0) {
			_rc_scan_begin = cycle_timestamp;
			// Configure serial port for SBUS
			sbus_config(_rcs_fd, board_rc_singlewire(_device));
			rc_io_invert(true);

			// flush serial buffer and any existing buffered data
			tcflush(_rcs_fd, TCIOFLUSH);
			memset(_rcs_buf, 0, sizeof(_rcs_buf));

		} else if (_rc_scan_locked
			   || cycle_timestamp - _rc_scan_begin < rc_scan_max) {

			// parse new data
			if (newBytes > 0) {
				bool sbus_failsafe = false;
				bool sbus_frame_drop = false;

				rc_updated = sbus_parse(cycle_timestamp, &_rcs_buf[0], newBytes, &_raw_rc_values[0], &_raw_rc_count, &sbus_failsafe,
							&sbus_frame_drop, &frame_drops, input_rc_s::RC_INPUT_MAX_CHANNELS);

				if (rc_updated) {
					// we have a new SBUS frame. Publish it.
					_rc_in.input_source = input_rc_s::RC_INPUT_SOURCE_PX4FMU_SBUS;
					fill_rc_in(_raw_rc_count, _raw_rc_values, cycle_timestamp,
						   sbus_frame_drop, sbus_failsafe, frame_drops);
					_rc_scan_locked = true;
				}
			}

		} else {
			// Scan the next protocol
			rc_io_invert(false);
		}

		perf_end(_cycle_perf);

		if (rc_updated) {
			perf_count(_publish_interval_perf);

			_to_input_rc.publish(_rc_in);

		} else if (!rc_updated && (hrt_elapsed_time(&_rc_in.timestamp_last_signal) > 1_s)) {
			_rc_scan_locked = false;
		}

		if (!rc_scan_locked && _rc_scan_locked) {
			PX4_INFO("RC input locked");
		}

	}
}

int RcSbus::custom_command(int argc, char *argv[])
{
	if (!is_running()) {
		int ret = RcSbus::task_spawn(argc, argv);

		if (ret) {
			return ret;
		}
	}

	return print_usage("unknown command");
}

int RcSbus::print_status()
{
	PX4_INFO("Max update rate: %u Hz", 1000000 / _current_update_interval);

	if (_device[0] != '\0') {
		PX4_INFO("UART device: %s", _device);
		PX4_INFO("UART RX bytes: %"  PRIu32, _bytes_rx);
	}

	PX4_INFO("RC state: %s", _rc_scan_locked ? "found" : "searching for signal");
	PX4_INFO("SBUS frame drops: %u", sbus_dropped_frames());

#if ADC_RC_RSSI_CHANNEL

	if (_analog_rc_rssi_stable) {
		PX4_INFO("vrssi: %dmV", (int)(_analog_rc_rssi_volt * 1000.0f));
	}

#endif

	perf_print_counter(_cycle_perf);
	perf_print_counter(_publish_interval_perf);

	if (hrt_elapsed_time(&_rc_in.timestamp) < 1_s) {
		print_message(ORB_ID(input_rc), _rc_in);
	}

	return 0;
}

int RcSbus::print_usage(const char *reason)
{
	if (reason) {
		PX4_WARN("%s\n", reason);
	}

	PRINT_MODULE_DESCRIPTION(
		R"DESCR_STR(
### Description
This module does the RC input parsing and auto-selecting the method. Supported methods are:
- SBUS

)DESCR_STR");

	PRINT_MODULE_USAGE_NAME("rc_sbus", "driver");
	PRINT_MODULE_USAGE_COMMAND("start");
	PRINT_MODULE_USAGE_PARAM_STRING('d', "/dev/ttyS3", "<file:dev>", "RC device", false);

	PRINT_MODULE_USAGE_DEFAULT_COMMANDS();

	return 0;
}

extern "C" __EXPORT int sbus_main(int argc, char *argv[])
{
	return RcSbus::main(argc, argv);
}