urgent! Help Check if My Circuit is Correct!

[Samuel Onesimus]

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..

 

[karthi_keyan]

hai samuel,


nice design ya,here some correction

1. Put 0.1 uf capacitor near by controller between vcc and vss.
2. key bounce capacitor in MCLR and switches will help u to get correct pulse form status.
3.see the current rate of stepper motor and selected driver. if stepper takes more current than driver it ll get heat and also u need to change the powr supply design using some other.becoz u cant put heat sink for LM317 with ground.
4.its confusing why u connect 9v battery with LM317 out.(something strange).
5.if u are continuously using stepper in ON,there may be a chance to EMI to get in to ur controller. refer some other design how to protect controller from back emf of Stepper.

regards,

karthikeyan

 

[wizpic]

hi samuel,
Before you design the PCB does your desing work from your schematic ?

Have you built a proto-type from it, If not I would recomend that you build it first either on vero board or bred board and get working project then you can design your PCB for it. I know some one who made the same mistake desgined the PCB had 10 boards made only to find out that it was wrong and the boards became scrap.
You can use a LM317 with heatsink you just use a insulator between the heatsink and LM317. If it only runs foma 9V battery then I would use just a standard LM7805 either 0.5A or 1A has for the 3.3V for the sd card you could use this simple circuit just use R1,C1,C2,D1 ignoring the TX module.
I've not studied to hard to look for errors but really your the only one who knows has you are designing it and know what it is for