PX4-Autopilot/src/systemcmds/tests/test_uart_loopback.c

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/**
 * @file test_uart_loopback.c
 * Tests the uart outputs.
 *
 * @author Lorenz Meier <lorenz@px4.io>
 */

#include <px4_platform_common/px4_config.h>

#include <sys/types.h>

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#include "tests_main.h"

#include <math.h>
#include <float.h>

int test_uart_loopback(int argc, char *argv[])
{

	int uart5_nread = 0;
	int uart2_nread = 0;
	int uart5_nwrite = 0;
	int uart2_nwrite = 0;

	/* opening stdout */
	int stdout_fd = 1;

	int uart2 = open("/dev/ttyS1", O_RDWR | O_NONBLOCK | O_NOCTTY);

	if (uart2 < 0) {
		printf("ERROR opening UART2, aborting..\n");
		return uart2;
	}

	int uart5 = open("/dev/ttyS2", O_RDWR | O_NONBLOCK | O_NOCTTY);

	if (uart5 < 0) {
		if (uart2 >= 0) {
			close(uart2);
		}

		printf("ERROR opening UART5, aborting..\n");
		return 1;
	}

	uint8_t sample_stdout_fd[] = {'C', 'O', 'U', 'N', 'T', ' ', '#', '\n'};
	uint8_t sample_uart2[] = {'C', 'O', 'U', 'N', 'T', ' ', '#', 0};
	uint8_t sample_uart5[] = {'C', 'O', 'U', 'N', 'T', ' ', '#', 0};

	int i, r;

	for (i = 0; i < 1000; i++) {
//		printf("TEST #%d\n",i);
		write(stdout_fd, sample_stdout_fd, sizeof(sample_stdout_fd));

		/* uart2 -> uart5 */
		r = write(uart2, sample_uart2, sizeof(sample_uart2));

		if (r > 0) {
			uart2_nwrite += r;
		}

//		printf("TEST #%d\n",i);
		write(stdout_fd, sample_stdout_fd, sizeof(sample_stdout_fd));

		/* uart2 -> uart5 */
		r = write(uart5, sample_uart5, sizeof(sample_uart5));

		if (r > 0) {
			uart5_nwrite += r;
		}

//		printf("TEST #%d\n",i);
		write(stdout_fd, sample_stdout_fd, sizeof(sample_stdout_fd));

		/* try to read back values */
		do {
			r = read(uart5, sample_uart2, sizeof(sample_uart2));

			if (r > 0) {
				uart5_nread += r;
			}
		} while (r > 0);

//		printf("TEST #%d\n",i);
		write(stdout_fd, sample_stdout_fd, sizeof(sample_stdout_fd));

		do {
			r = read(uart2, sample_uart5, sizeof(sample_uart5));

			if (r > 0) {
				uart2_nread += r;
			}
		} while (r > 0);

//		printf("TEST #%d\n",i);
//		write(stdout_fd, sample_stdout_fd, sizeof(sample_uart5));
	}

	for (i = 0; i < 200000; i++) {

		/* try to read back values */
		r = read(uart5, sample_uart2, sizeof(sample_uart2));

		if (r > 0) {
			uart5_nread += r;
		}

		r = read(uart2, sample_uart5, sizeof(sample_uart5));

		if (r > 0) {
			uart2_nread += r;
		}

		if ((uart2_nread == uart2_nwrite) && (uart5_nread == uart5_nwrite)) {
			break;
		}
	}


	close(stdout_fd);
	close(uart2);
	close(uart5);

	printf("uart2_nwrite %d\n", uart2_nwrite);
	printf("uart5_nwrite %d\n", uart5_nwrite);
	printf("uart2_nread  %d\n", uart2_nread);
	printf("uart5_nread  %d\n", uart5_nread);


	return 0;
}