Pololu Jrk USB - Manual (Page 39)

#include
#include
#include
#ifdef _WIN32
#define O_NOCTTY 0
#else
#include
#endif
// Reads a variable from the jrk.
// The 'command' argument must be one of the two-byte variable-reading
// commands documented in the "Variable Reading Commands" section of
// the jrk user's guide.
int jrkGetVariable(int fd, unsigned char command)
{
if(write(fd, &command, 1) == -1)
{
perror("error writing");
return -1;
}
unsigned char response[2];
if(read(fd,response,2) != 2)
{
perror("error reading");
return -1;
}
return response[0] + 256*response[1];
}
// Gets the value of the jrk's Feedback variable (0-4095).
int jrkGetFeedback(int fd)
{
return jrkGetVariable(fd, 0xA5);
}
// Gets the value of the jrk's Target variable (0-4095).
int jrkGetTarget(int fd)
{
return jrkGetVariable(fd, 0xA3);
}
// Sets the jrk's Target variable (0-4095).
int jrkSetTarget(int fd, unsigned short target)
{
unsigned char command[] = {0xC0 + (target & 0x1F), (target >> 5) & 0x7F};
if (write(fd, command, sizeof(command)) == -1)
{
perror("error writing");
return -1;
}
return 0;
}
int main()
{
// Open the Jrk's virtual COM port.
const char * device = "\\\\.\\USBSER000"; // Windows, "\\\\.\\COM6" also works
//const char * device = "/dev/ttyACM0"; // Linux
//const char * device = "/dev/cu.usbmodem00000041"; // Mac OS X
int fd = open(device, O_RDWR | O_NOCTTY);
if (fd == -1)
{
perror(device);
return 1;
}
#ifndef _WIN32
struct termios options;
tcgetattr(fd, &options);
options.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
options.c_oflag &= ~(ONLCR | OCRNL);
tcsetattr(fd, TCSANOW, &options);
#endif
Pololu Jrk USB Motor Controller User's Guide © 2001–2014 Pololu Corporation
4. Using the Serial Interface Page 39 of 45