Previous

Next

Printer Class Driver

The printer driver supports all USB printers using USB class 7 (Printer), subclass 1, and protocol 1 or 2 (uni- or bidirectional). Up to four printers can be operated simultaneously; additional printers are ignored.

The driver is registered using its callback USBPrinter. USBPrinterInfo can be called to return a string with information about an attached printer. USBPrinterStatus returns the current printer status. USBPrinterInit can be used to initialize and reset a printer. USBPrintData sends data to print to a printer and USBPrintCancel cancels all pending print jobs.

Example:

int main(void) 
{ 
   RTURegisterCallback(USBKeyboard); // include USB keyboard driver 
   RTURegisterCallback(USBPrinter);  // and USB printers 
   FindUSBControllers();             // start USB 

   RTUWaitInitialEnumDone();         // wait until the USB stack has 
                                     // found all attached devices 

   int PrinterIndex = 0; 
   const char * PInfo = USBPrinterInfo(PrinterIndex); 

   if (PInfo == NULL) 
   { 
      printf("sorry, no printer found\n"); 
      exit(1); 
   } 
   else 
      printf("Printer info: %s\n", PInfo); 

   // let's assume the printer can print ASCII data. 
   const char * Hello = "Hello, USB Printer!\n\f"; 

   BYTE Result = USBPrintData(PrinterIndex, Hello, strlen(Hello), 5000); 

   if (Result & USB_PRN_OUT_OF_PAPER) 
      printf("Out of paper\n"); 
   if (Result & USB_PRN_TIMEOUT) 
      printf("timeout\n");           // could do a retry here 
   if (Result & USB_PRN_IO_ERROR) 
      printf("I/O error or printer disconnected\n"); 
   if ((Result & USB_PRN_SELECTED) == 0) 
      printf("printer offline?\n"); 

   return 0; 
}

The RTUSB-32 Reference Manual contains additional information about the driver's API.

Class Drivers

Touch Screen Driver

Mass Storage Class Driver