dm6430-digital-io.c

来自「rt 6430 采集卡 linux下驱动源代码」· C语言 代码 · 共 131 行

/*
	FILE NAME: dm6430-digital-io.c

	FILE DESCRIPTION: Digital I/O sample program

		Sample program that demonstrates how to read and write the
		digital I/O ports.  The program constantly displays the value
		of the input port lines on the screen.  Wiring the input port
		lines to the corresponding output port lines will allow you to
		change the output lines and view the changes at the same time.

		Port 0 is used for input and port 1 is used for output.

	PROJECT NAME: Linux DM6430 Driver, Library, and Example Programs

	PROJECT VERSION: (Defined in README.TXT)

	Copyright 2004 RTD Embedded Technologies, Inc.  All Rights Reserved.
*/


#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/poll.h>
#include <unistd.h>

#include <dm6430lib.h>


char *program_name_p;


static void
usage(void) {
    fprintf(
	stderr,
	"\n"
        "Usage: %s MINOR_NUMBER"
        "\n",
	program_name_p
    );
    exit(EXIT_FAILURE);
}


static void
verify_success(int status, const char *message_p) {
    if (status == -1) {
	perror(message_p);
	exit(EXIT_FAILURE);
    }
}


static int
isstdindata(int timeout) {
    struct pollfd	in = {0, POLLIN | POLLERR | POLLPRI, 0};
    int			num_fds;

    while (((num_fds = poll(&in, 1, timeout)) == -1) && (errno == EINTR))
	;

    return ((num_fds == 1) && (in.revents & (POLLIN | POLLPRI)));
}

int
main(int argument_count, char **arguments_p_p) {
    int			descriptor;
    int			status;
    unsigned int	minor_number;
    u_int8_t		output_value;

    program_name_p = arguments_p_p[0];

    if (argument_count != 2) {
	fprintf(stderr, "Invalid number of options given.\n");
	usage();
    }

    if (sscanf(arguments_p_p[1], "%u", &minor_number) == 0) {
	fprintf(stderr, "Invalid device minor number.\n");
	usage();
    }

    descriptor = OpenBoard6430(minor_number);
    verify_success(descriptor, "OpenBoard6430() FAILED");

    status = InitBoard6430(descriptor);
    verify_success(status, "InitBoard6430() FAILED");

    status = DIOSetPort0Direction6430(descriptor, 0);
    verify_success(status, "DIOSetPort0Direction6430() FAILED");
    status = DIOSetPort1Direction6430(descriptor, 1);
    verify_success(status, "DIOSetPort1Direction6430() FAILED");

    fprintf(stdout, "Digital output at port 1\n");
    fprintf(stdout, "Digital input at port 0.\nPress Enter for stop\n");

    /*
     * Start digital output value at 0.  This will be updated in the loop
     * below to provide different values.
     */

    output_value = 0;

    while (!isstdindata(200)) {
	unsigned char	input_value;

	status = DIOWrite6430(descriptor, DM6430HR_DIO1, output_value);
	verify_success(status, "DIOWrite6430() FAILED");

	fprintf(stdout, "DIO(1) output: 0x%02x", output_value);

	status = DIORead6430(descriptor, DM6430HR_DIO0, &input_value);
	verify_success(status, "DIORead6430() FAILED");

	fprintf(stdout, ", DIO(0) input: 0x%02x\n", input_value);

	/*
	 * Make a different digital output value.  When it reaches 255, it will
	 * overflow to 0 and start all over again.
	 */

	output_value++;
    }

    exit(EXIT_SUCCESS);
}