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

[rjones2102]

OK you guys,

I am a very very happy man!! I can teach you something now. I doubt you will ever need to know it as you are probably not as careless as me but just in case you are as tired as me one day and stuff up!!

I built the circuit on breadboard with ICSP, LEDs, MAX232, USB and all the bits necessary to debug. I copied the wiring for the USB connections from the prototype board. Guess what, it didn't work. I used the luxury of breadboarding to swap cap values and crystals etc but all to no avail.

I decided I had to check my breadboard wiring. I got the EasyHID schematic out and checked the breadboard and then had to check the proto board to see if it could be true. Here comes the lesson:

If you get D+ and D- the wrong way round it might work sometimes!!!!

I definitely don't recommend it as it took me 3 days (incredibly long ones as well!!) to find it. If it weren't intermittent it would have been so much easier. I used to be a TV engineer 25 years ago and this whole thing takes me back a long way. Intermittent faults are a nightmare!

I just want to thank you guys for holding my hand through this trauma and I just want to add:

"There's no problem. Only learning opportunities"

Now where have I heard that before. I'm elated with how much I have learned!

The other person I would like to quote is Alain, AKA Altronics. "If there is the word Problem in the question, the answer is almost certainly RTFM". He is so right but I need one piece of info to make him right for me..... Does anyone know of any good books on how to understand a Microchip Datasheet? PBP books just don't cut it.

Cheers a very lot, back to the wonderful world of coding!

Rich