dm6430-dac.c

rt 6430 采集卡 linux下驱动源代码

/*
	FILE NAME: dm6430-dac.c

	FILE DESCRIPTION: Digital to analog conversion sample program

		Sample program that demonstrates how to use the analog output.

		This program uses the digital to analog converters on the A/D
		board.  If you wire the D/A channel to this A/D channel	you
		can monitor the output of the DAC directly on your computer.
		Alternatively, you can monitor the output of the DAC with an
		oscilloscope.

	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 <limits.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)));
}


#define	AD_CHAN4	DM6430HR_AIN1		// Channel to read D/A data back
#define	GAIN4		DM6430HR_GAINx1		// Gain (for A/D)
#define	SE_DIFF4	DM6430HR_SE_SE		// Single-ended
#define	AD_SLOPE4	(65536.0/20.0)		// Number Bits divided by AD Range

#define	DAC_SLOPE4	(65536.0/20.0)		// Number Bits divided by DAC Range
#define	DAC_OFFSET4	2048			// Offset of the output line signal


int
main(int argument_count, char **arguments_p_p) {
    int			descriptor;
    int			status;
    short		DAData;
    short		dac_base;
    unsigned int	minor_number;

    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 = SetConversionSelect6430(descriptor, DM6430HR_CONV_SOFT_TRIGGER);
    verify_success(status, "SetConversionSelect6430() FAILED");

    status = SetChannelGain6430(descriptor, AD_CHAN4, GAIN4, SE_DIFF4);
    verify_success(status, "SetChannelGain6430() FAILED");

    status = ClearADFIFO6430(descriptor);
    verify_success(status, "ClearADFIFO6430() FAILED");

    /*
     * Base value for data written to D/A converter.  This value is modified
     * as the loop below is executed to allow one to see changes in the A/D
     * data
     */

    dac_base = 0;

    while (!isstdindata(200)) {
	int	empty_flag;
	int16_t	data;

	DAData = (dac_base * DAC_SLOPE4) + DAC_OFFSET4;
	status = LoadDAC6430(descriptor, DAData);
	verify_success(status, "LoadDAC6430() FAILED");

	status = StartConversion6430(descriptor);
	verify_success(status, "StartConversion6430() FAILED");

	do {
	    status = IsADFIFOEmpty6430(descriptor, &empty_flag);
	    verify_success(status, "IsADFIFOEmpty6430() FAILED");
	} while (empty_flag);

	status = ReadADData6430(descriptor, &data);
	verify_success(status, "ReadADData6430() FAILED");
	fprintf(stdout, "IN = %2.2lf mV\n", data / AD_SLOPE4);

	/*
	 * Increment base value for D/A data.  Only allow it to assume values
	 * in the range [0, 9] because, due to the way the D/A value is
	 * calculated in this program, these base values cause changes in A/D
	 * value.
	 */

	dac_base++;
	if (dac_base == 10) {
	    dac_base = 0;
	}
    }

    status = LoadDAC6430(descriptor, 0);
    verify_success(status, "LoadDAC6430() FAILED");

    exit(EXIT_SUCCESS);
}