Problem with using two outputs of a power supplier for PIC and ULN2003

[silencer80]

Dear All
I have a power supplier with two outputs one 12v-2A and the other is 5v-2A
I want to use the 5v for supply the pic with the voltage & the 12v to supply ULN2003 to drive a bipolar stepper motor with rated current .4 A
the question is do I need pull up resistor at the input of the pic
& do I need to do so for the input of the uln2003
& is the uln will be good with the stepper motor or I need Another drive cct
& I have aproblem in programming with interfacing the lCD with pic where I use 4 bit mode & the WR pin is connected to ground when I try to move the cursor to a specific place it goes to it but then the character output becomes wrong
Please Answer me As soon as possiple
thanks alot

 

[matbob]

Re: V I Question

Hi silencer80,

First of all, you cannot use ULN2003 for a BIPOLAR stepper motor since it can only sink current and can't source current. You may use L293D instead and it is rated for 600mA continuous.

'do I need pull up resistor at the input of the pic' -please make the question little more clear. Pullup at which pin?

 

[silencer80]

Re: V I Question

Dear matbob
I'm very thankfull for your help about the uln2003 can I use it with unipolar with the 12v and .4A
now about the pull up resistor I mean VDD pin
& if you can help me in the LCD I use 4 X 20 lcd put when positioning the cursor at the second or the fourth nothing appear put the other lines is good
thanks alot

 

[matbob]

Re: V I Question

Hi silencer80,

Regarding ULN2003, the rated current is 500mA per channel but you may parallel the outputs if you require more.

Why should you 'pullup' the VDD pin of PIC? The VDD pin is meant directly to be connected to the 5V supply.

For 4x20 displays the display data ram (DDRAM) address may vary with manufacturers.
I think you should go through the datasheets throughly before posting questions. Do your homework first!!