[Samuel Onesimus]

urgent! Help

Hi,

Ive designed a circuit which is a PIC18F4550 based. which uses SDCard, USB , Key Buttons, Piezoelectric Speaker, and drives 7 Stepper motors.. It might have errors in it.. I need to Design PCB board immeditely.. It would be very helpfull if the errors are spoted.. Pls Help.. I've attached the Circuit here..

[rnr107]

Hi Samuel,
It looks like your stepper motors can only spin in 1 direction... Is it what you want?

Also, check RA4. I think it not a TTL output level... It may requiere a pull up or something.

You may need a faster crystal (To run USB 2) if you run the motors a bit fast or in complex movement. (Have a look at the PIC datasheet for the list of crystal supported)

Have you got any USB coding experience? Because it is a bit complicated if you start from scrach...

Hope this help,
RNR

[Samuel Onesimus]

Hi Samuel,
It looks like your stepper motors can only spin in 1 direction... Is it what you want?

Also, check RA4. I think it not a TTL output level... It may requiere a pull up or something.
..
Have you got any USB coding experience? Because it is a bit complicated if you start from scrach...
RNR

Thanks RNR,
Ya want it all to apin in 1 direction..
I checked RA4.. I'm having problem as u said.. But i do not Know how to do it,( USE PULL UP or Something).. Can u help..
and abt USB, I'm using MikroC's LIB.. SO no much problem with it..

[rnr107]

I'll have a look at the datasheet for you. But you may have to use a different pin...

RNR

[rnr107]

Samuel,
I had a quick look at the datasheet, you should not tneed any pul ups...
But you need to make sure you clear all the bits of the TRIS_A register. By default some of the pins of port A are set to input. And RA4 is share function with USB (When using external USB device) and with Timer0 input trigger.
Make sure use declare and specify the use of Internal USB device. And do you use Timer0 in your code?

What is "MikroC's LIB" ? Do you mean Microchip? what compiler are you using?

RNR

[Samuel Onesimus]

yes.. I use Timer0..
And MiKroC is a Compiler for PIC, I'm using tat.. It has library to support USB functions..