This example uses LibUSB to interface to the U4x1.
Example Code
| ⁄* uses libusb version 0.1.10a found at http:⁄⁄libusb.sourceforge.net *⁄ #include “libusb⁄usb.h” #define VENDOR_ID 0x0DE7 #define PRODUCT_ID 0x0191 #define CANT_SEND -1 #define CANT_READ -2 static struct usb_device *find_U401( struct usb_bus *bus ) { struct usb_device *dev; ⁄⁄ look through all busses for ( ; bus; bus = bus->next ) { ⁄⁄ look at every device for ( dev = bus->devices; dev; dev = dev->next ) { ⁄⁄ match to known IDs if ( dev->descriptor.idVendor == VENDOR_ID && dev->descriptor.idProduct == PRODUCT_ID ) { return dev; } } } return NULL; } void buffer_set( char *buf, int a, int b, int c, int d, int e, int f, int g, int h ) { buf[0] = a; buf[1] = b; buf[2] = c; buf[3] = d; buf[4] = e; buf[5] = f; buf[6] = g; buf[7] = h; } int send_command( struct usb_dev_handle *handle, char *command, int comLen, int resLen ) { int ret = usb_control_msg( handle, 0x21, 9, 0x0200, 0, command, comLen, 5000 ); ⁄⁄ check that the send was successful if ( ret != comLen ) return CANT_SEND; ⁄⁄ does the command expect a result? if ( resLen > 0 ) { ret = usb_bulk_read( handle, 0x81, command, resLen, 5000 ); if ( ret != resLen ) return CANT_READ; } return ret; } int main() { int busses, devices, ret, portA, portB; struct usb_bus *bus_list; struct usb_device *dev = NULL; struct usb_dev_handle *handle; char buffer[8]; ⁄⁄ initialize the usb system usb_init(); busses = usb_find_busses(); ⁄⁄ update info on busses devices = usb_find_devices(); ⁄⁄ update info on devices bus_list = usb_get_busses(); ⁄⁄ get actual bus objects if ( ( dev = find_U401(bus_list) ) == NULL ) return -1; ⁄⁄ failure to find if ( ( handle = usb_open(dev) ) == NULL || usb_claim_interface( handle, 0 ) ) return -1; ⁄⁄ failure to open if ( usb_set_configuration(handle, 1) ) return -1; ⁄⁄ initialize the ports (A & B) as input buffer_set( buffer, 0, 0, 0, 0, 0, 0, 0, 0 ); ret = send_command( handle, buffer, 8, 0 ); if ( ret != 8 ) return -1; ⁄⁄ read port A buffer_set( buffer, 0x05, 0, 0, 0, 0, 0, 0, 0 ); ret = send_command( handle, buffer, 8, 8 ); if ( ret != 8 ) return -1; ⁄⁄ report error ⁄⁄ print out port A value printf( “Port A = %d\n”, buffer[1] & 0xFF ); ⁄⁄ read port B buffer_set( buffer, 0x06, 0, 0, 0, 0, 0, 0, 0 ); ret = send_command( handle, buffer, 8, 8 ); if ( ret != 8 ) return -1; ⁄⁄ report error ⁄⁄ print out port B value printf( “Port B = %d\n”, buffer[1] & 0xFF ); if ( usb_release_interface(handle, 0) || usb_close(handle) ) return -1; ⁄⁄ report error return 0; ⁄⁄ success } |
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