Vusb capacitor for USB comms with 18f2550

[mister_e]

To me serial test, Timer AND/OR PWM test is a nice start point to check a crystal accuracy, so configuration fuses setting too. PAUSE is not a safe test to me. OK OK, let's say your PAUSE 1000 take twice or half the time... you obviously see something is bad. But 1/4,1/10,1/100 second off on a 10 second delay... is hard to see. Serial comm on a high baudrate such as 115200 baud, would be a nice reference, even 19200 is still not bad.

Ceramic resonator are nice, but might shift with temperature, less than the internal OSC that's for sure, but not as accurate as Crystal. Some resonator have built-in cap, some not.

Good pcb, usb connector/cable debugging