Need Help!- Reversed Logic voltage to PICSTEP- What component to be replaced?

[Khalid]

I have developed the Picstep version 4 board but i did not install the IDC cable as my BOB only requires STEP and DIR signals. Today i accidentally reversed the Logic voltage cables so that instead of installation of +5V DC wire to the +5V Logic i install the +5V to the Gnd... The result was my PIC become too hot as soon i realize what i did wrong i removed the cables...

Fortunately most of the capacitors are ceramic or MKT type (non polar) so i am not worried about them But:
1- I am sure that the PIC is blown away.
2- What components else might be blown away?... XTAL and LMD?????

Anyone can tell me should i replace all the components and discard them? Or should i replace the 20MHz XTAL?

[Al_The_Man]

I doubt if the XTAL was damaged as it usually is connected to two pins on the PIC and isolated from DC -ve by two caps, if this is the configuration you have?
Probably just the PIC suffered, if you have any electrolytic's or Tantalum on board, you could remove them and test if need be.
Al.

[Khalid]

Thanks Al, I do have the electrolytic on the board.. I hae replaced the PIC as well as the Xtal.. Two wires (+5V and GND) from the ATX computer power supply, i am using to give the Logic voltage to the PICstep... I have connected 24VDC and GND on the PICstep board for Motor powering.. My Motor has total 6 wires so i have just left the both COMMON wires unconnected..the rest of the 4 wires are connected to the board A A' and B B'...

Following is my observation... With the motor connected and the both the Power supply enabled and the PIC install..My motor do not hold...

But when i keep finger under the PIC and Xtal soldering joints, Motor holds and i can't rotate it by fingers... But as i removed the fingers from the Xtal/Pic soldering joints the motor do not hold..
I thought that the cold solder may be their but the Digital Meter shows continiuty of all the joints...

1-Whats going wrong?
2- Should i make ENABLE pin to ground?
3-If the Motors hold it means that LMD and other Electrolytic capacitors are working well...

NOTE:
I am using 20MHz Xtals with 22PF capacitors.

[Al_The_Man]

I had a weird problem like that once and the reason turned out to be the fact I had not had the right config string in the asm code and the power up reset was not set for internal pull up.
Every time if I touched the board it would set it.
Is this a pre-programmed Pic or are you programming it? What PIC IC is it?.
If there is nothing connected to the Master Clear pin, you could take it high to see if it runs.
Al.

[Al_The_Man]

I found a schematic of the board, and MCLR pin 1 goes to +5 so it may not be the cause if this is connected.
What about the stop input?
Al.

[robe_uk]

Hi
you have to ground the enable line and also feed a step pulse for the motors to hold. So tie your enable to ground, with standard code the motors will not hold till it see's a pulse on the step pin.


Cheers Rob

[robe_uk]

did you get your pic's programmed ok?

[Khalid]

@Al:
I have QL-2006 advance PIC programmer and i am programming the PIC Myself. Hex code uploaded to the PIC successfully without Error with all Configuration Bits. Attached is also the screen shot of software after reading Back the Hex code from the PIC. The Right side of the initial and re-read Hex file has different characters and i think this is due to the placing of configuration bits.

What do you mean by STOP input.Please clarify.

@robe_uk:
A) I have ground the Enable Pin 01 to the GROUND with a Jumper but nothing happen. The motor do not hold.
B) As the Modular Card PICSTEP is not connected to the BOB, so can i externally give inputs to the STEP PIN?
Should i provide +5V DC to step pin to check or connect it to GND. Your help and opinion needed.

C) The PIC is programmed successfully as per attached picture and above points.

[Khalid]

If someone have a working HEX file can share with me please.

[Khalid]

Hmmm... In above picture i have mistakenly selected PIC 16LF628A but whether this may be the cause of trouble?

[doorknob]

Originally Posted by Khalid Following is my observation... With the motor connected and the both the Power supply enabled and the PIC install..My motor do not hold... But when i keep finger under the PIC and Xtal soldering joints, Motor holds and i can't rotate it by fingers... But as i removed the fingers from the Xtal/Pic soldering joints the motor do not hold.. I thought that the cold solder may be their but the Digital Meter shows continiuty of all the joints...

I have no experience with that circuit, but I am wondering whether the symptom you have described could be caused by a balky oscillator, with a crystal that does not want to start oscillating.

Is there any indication on the board (such as a blinking LED that is under the direct control of the PIC firmware) that the PIC is actually getting a clock signal when you don't have your finger under the crystal circuitry? If the oscillator does not start reliably then you will have problems. It might be possible that the capacitance values that you are using are not well matched to the crystal.

[Al_The_Man]

Is this the schematic you are working with?
http://www.jrkerr.com/pstep_bd.pdf
There is an active high E-stop input, which would indicate that this has to be taken low to remove the stop.
My programmer won't allow a different PIC than designated to be programmed?
What is the PIC you are using?
Al.