Hi Andy - 

 I had my DS1050-025 running, for a while, but now I can only get about 3 to 10 cycles out it.  I have gone back over changes I have made, but nothing seems to help.  Here is the test code I am currently trying.  I open the DS1050 i2c, using address 0x28 ( as shown by i2cdetect on my Raspberry Pi, which this hardware is on).  Then I write 0x50 (set PMW command) followed by the data (shown as 0x10h - which should be 50% PWM).

I close the file descriptor, call the second function, where I open the DS1050 in i2c again, writing 0x50 (set PWM command) followed by the data 0x20 as shown on the DS1050 data sheet.  Then again close the file descriptor.  I have tried combining the two functions and write 0x50, 0x10, 0x50, 0x20 and the close i2c with the same results.

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "/home/dvf/glg/include/GlgApi.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>    // read/write usleep     
#include <inttypes.h>  // uint8_t, etc
#include <linux/i2c-dev.h> // I2C bus definitions
#include <sys/ioctl.h>			//Needed for I2C port
#include "/home/dvf/glg/include/GlgApi.h"
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>


#include <termios.h>

#include <stdio.h>
#include <sys/types.h> // open
#include <sys/stat.h>  // open
#include <fcntl.h>     // open
#include <unistd.h>    // read/write usleep
#include <stdlib.h>    // exit
#include <inttypes.h>  // uint8_t, etc
#include <linux/i2c-dev.h> // I2C bus definitions
#include <sys/ioctl.h>
#include "PWM.h"
int PWM_Write2(void);
int fd_pwm, fd;
   int16_t val;
   uint8_t writeBuf[5], readBuf[2];

void main(void)
{
   

   // open device on /dev/i2c-1 
   if ((fd_pwm = open("/dev/i2c-1", O_RDWR)) < 0) 
   {
      printf("Error: Couldn't open I2C device\n");
      return;
   }

   // connect to ads1115 as i2c slave
   if (ioctl(fd_pwm, I2C_SLAVE, PWM_Addrs) < 0)
    {
      printf("Error: Couldn't find device on address!\n");
      return;
   }
   // set config register and start conversion

   writeBuf[0] = SetPWM;    // config register is 1
   writeBuf[1] = 0x10;
  // Set newm PWM duty
   if (write(fd_pwm, writeBuf, 4) != 4) 
   {
       printf("Can't write to register 1\n");
       return;
   }

   close(fd_pwm);

   PWM_Write2();
   while(1)
{
   ;
}

}

int PWM_Write2(void)
{
   // open device on /dev/i2c-1 
   if ((fd = open("/dev/i2c-1", O_RDWR)) < 0) {
      printf("Error: Couldn't open I2C device\n");
      return 1;
   }
printf("fd = %d\n",fd);
   // connect to ads1115 as i2c slave
   if (ioctl(fd, I2C_SLAVE, PWM_Addrs) < 0) {
      printf("Error: Couldn't find device on address!\n");
      return 1;
   }
// set config register and start conversion

   writeBuf[0] = SetPWM;    // config register is 1
   writeBuf[1] = 0x20;
   // Set newm PWM duty
   if (write(fd, writeBuf, 2) != 2) 
   {
       printf("Can't write to register 1\n");
       return 1;
   }

	close(fd);
}

Hope you can help,

David
YouTube "Sailing Solo at 70"