linux_usb_iss_spi.c

/*******************************************************
* USB-ISS test application for Linux.                  *
*                                                      *
* Sets USB-ISS into spi mode and reads and writes from *
* microchips 23k256                                    *
*                                                      *
* Compiled using  gcc, tested on Ubunto 10.4 LTS.      *
*                                                      *
* By James Henderson, 2012.                            *
*******************************************************/

//
// Credit goes to the above person for this short but awesome program.
// I modified it slightly to read the information string from the
// Alphasense OPC-N2 sensor.
//

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

void display_version(void);
void set_spi_mode(void);
void read_data(void);

void wait_comseq() {
  struct timespec msec10;
  msec10.tv_sec = 0;
  msec10.tv_nsec = 10000000;
  nanosleep(&msec10, NULL);
}

int fd;
int error = 0;
unsigned char sbuf[64];			// serial buffer for r/w


int main(int argc, char *argv[])
{
	printf("******************************\n");
	printf("USB ISS linux test application\n");
	printf("By James Henderson, 2012\n");
	printf("******************************\n\n");

	if(argc != 2)
		printf("Incorrect input!\n");
	else
	{
		struct termios defaults;							// to store innitial default port settings
		struct termios config;								// These will be our new settings
		const char *device = "/dev/ttyACM0";
		fd = open(device, O_RDWR | O_NOCTTY);
		if(fd == -1) {
  			printf( "failed to open port\n" );
		} else {
			if (tcgetattr(fd, &defaults) < 0) perror("tcgetattr");  		// Grab snapshot of current settings  for port
			cfmakeraw(&config);							// make options for raw data
			if (tcsetattr(fd, TCSANOW, &config) < 0) perror("tcsetattr config");   	// Set options for port

			display_version();
			set_spi_mode();

      if (!error) read_data();

			if (tcsetattr(fd, TCSANOW, &defaults) < 0) perror("tcsetattr defaults");	// Restore port default before closing
		}
		close(fd);
	}
	return 0;
}

void display_version(void)
{
	sbuf[0] = 0x5A; 						// USB_ISS byte
	sbuf[1] = 0x01;							// Software return byte

	if (write(fd, sbuf, 2) < 0) perror("display_version write");	// Write data to USB-ISS
	if (tcdrain(fd) < 0) perror("display_version tcdrain");
	if (read(fd, sbuf, 3) < 0) perror("display_version read");	// Read data back from USB-ISS, module ID and software version

	printf("USB-ISS Module ID: %u \n", sbuf[0]);
	printf("USB-ISS Software v: %u \n\n", sbuf[1]);
}

void set_spi_mode(void)
{
	sbuf[0] = 0x5A;
	sbuf[1] = 0x02;			// Set mode command
	sbuf[2] = 0x92;			// Set SPI mode
	sbuf[3] = 0x0B;			// 500KHz clock speed

	if (write(fd, sbuf, 4) < 0) perror("set_spi_mode write");	// Write data to USB-ISS
	if (tcdrain(fd) < 0) perror("set_spi_mode tcdrain");
	if (read(fd, sbuf, 2) < 0) perror("set_spi_mode read");		// Read back error byte
	if(sbuf[0] != 0xFF)						// If first returned byte is not 0xFF then an error has occured
	{
		printf("**set_spi_mode: Error setting spi mode!** 0x%02x\n\n", sbuf[0]);
		error = 0xFF;						// Set error byte
	}
}


void read_data(void)
{

  for (int i=0;i<64;i++) {
    sbuf[i] = 0;
  }

	sbuf[0] = 0x61;
	sbuf[1] = 0x3F;
	sbuf[2] = 0x00;
	sbuf[3] = 0x00;
	sbuf[4] = 0x00;



	if (write(fd, sbuf, 2) < 0) perror("set_spi_mode write");	// Write data to USB-ISS
	if (tcdrain(fd) < 0) perror("set_spi_mode tcdrain");
//  wait_comseq();
	if (read(fd, sbuf, 2) < 0) perror("set_spi_mode read");		// Read back error byte

	sbuf[0] = 0x61;
	sbuf[1] = 0x3F;
  wait_comseq();
//	if (write(fd, sbuf, 2) < 0) perror("set_spi_mode write");	// Write data to USB-ISS
//	if (tcdrain(fd) < 0) perror("set_spi_mode tcdrain");
	if (write(fd, sbuf, 61) < 0) perror("set_spi_mode write");	// Write data to USB-ISS
	if (tcdrain(fd) < 0) perror("set_spi_mode tcdrain");
//  wait_comseq();
	if (read(fd, &sbuf, 61) < 0) perror("set_spi_mode read");		// Read back error byte

  for (int i=0;i<61;i++) {
//	  if (read(fd, &sbuf[i], 1) < 0) perror("set_spi_mode read");		// Read back error byte
    printf("%02x ", sbuf[i]);
  }
  printf("\n");

}