USB connection crashes 4800 baud serial emulation

[tinley]

Hi,

I am having trouble getting USB to work fast enough for my application. The application has two RS232 inputs, (each up to 50% active) at 4800 BAUD which it merges into one 4800 output. I also want to output this stream to USB. I have tried writing my own subroutine 'usbout()' which helps, but still it keeps crashing the USB connection.

Please help?

CCS PCH C Compiler, Version 3.249, 27988 09-May-06 15:48

Filename: USB_Merger.lst

ROM used: 6722 bytes (21%)
Largest free fragment is 26042
RAM used: 1617 (79%) at main() level
1704 (83%) worst case
Stack: 13 worst case (6 in main + 7 for interrupts)

void usbout(char *sl){ //////////////////////////////////////////////////////////////////////////
char *s;
for (s=sl; *s != '\0'; s++){
//while(!usb_cdc_putready()){ //wait for usb buffer
// restart_wdt();
//}
delay_ms(1); //this helps prevent usb crash
usb_cdc_putc(*s);
}
}

[tinley]

Fault found... hardware, not software. I hadn't fitted the 220n capacitor on the Vusb pin.

Interesting to note that with the amount of data and sentence lengths I am sending, (up to 100 chrs), the following function is still required as printf(usb_cdc_putc,txBuffer) crashes the USB! :

void usbout(char *sl){
char *s;
for (s=sl; *s != '\0'; s++){
usb_cdc_putc(*s);
}
}

usbout(txBuffer); //in place of printf(usb_cdc_putc,txBuffer);