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Thread: Reversed Logic voltage to PICSTEP- What component to be replaced?

  1. #37
    Community Moderator Al_The_Man's Avatar
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    How did you make out with the test HEX file?
    Any Luck.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


  2. #38
    Member Khalid's Avatar
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    Quote Originally Posted by Al_The_Man View Post
    How did you make out with the test HEX file?
    Any Luck.
    Al.
    Today i will test the HEX file. Please confirm have you included all the Configuration bits...

    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    Member Khalid's Avatar
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    Quote Originally Posted by robe_uk View Post
    I would doubt the motors would hold if there was no PIC.
    If motor not hold with removed PIC then this is a good symptom ,at-least for me as in my case motor not hold.
    Quote Originally Posted by robe_uk View Post
    I have one more suggestion, when i was originally testing i couldn't get my picstep to run until i tested using a 4.8v battery pack, i had been using a pc power supply for my 5v so when the picstep worked with the battery pack i assumed i have a bad pc psu or that the pc psu interfered with the picstep, so try using a battery pack or 7805 circuit for the 5v rather than the pc switched mode psu.

    Good luck
    I will definitly go to change of Power Supply and shall use LM7809 for input Logic supply to board. I will also try the whole setup with BOB and Mach3. May be due to not attaching the BOB i am getting problem.

    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


  4. #40
    Member Khalid's Avatar
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    Quote Originally Posted by amishx64 View Post
    I will see if I can help you diagnose the issue step-by-step. I have experience programming AVRs (like PICs) and quite a bit of experience with circuits.

    However, I am very busy both today and tomorrow, so I can't immediately be of assistance. I will post when I have some more time.
    I appreciate your help... and i will wait for your posts Amish.

    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
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    Member Khalid's Avatar
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    Looking at schematic of PICstep i found that their is no capacitor between MCLR pin and GND. Also when both the Jumpers removed i.e. (1/8 microstep) How the MCLR is pull down???

    Attached Thumbnails Attached Thumbnails Reversed Logic voltage to PICSTEP- What component to be replaced?-mclr-ground-jpg  
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    Any open inputs to your PIC can cause the finger touch behavior in the PIC Micro controller. Tie them either to VCC or VDD as appropriate through a 1k to 10k resistor. They act very much like antennas and make PICs do unexpected things. Install bypass capacitors across the pwr to ground supply pins as close to the PIC as practical, .01µF.



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    Member Khalid's Avatar
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    Hi Joe,
    Thank you for your valuable advice.. I am still puzzled many peoples around having working PICSteps...How and Why?

    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    Quote Originally Posted by Khalid View Post
    Hi Joe,
    Thank you for your valuable advice.. I am still puzzled many peoples around having working PICSteps...How and Why?
    Have you committed your Project to a PC board yet or are you still using a breadboard to prototype it? Those breadboards that you just push in the parts have tons of stray capacitance and, also; suffer with corrosion issues if they are old. I try to replace them yearly. Regarding your 33 vs 15 µF caps on the crystals, again the breadboards tend to add capacitance and is why you had to reduce the value, when using the PC board you will likely have to go back to the 33 µF units. You know, I have heard of nearby fluorescent lights causing them to act up too.
    Another thought the 16F628 is not the same as the 16F628A so be sure your compiler is set to the correct one. I am going to back in this thread to find the source code and see what it is telling the chip to do, if I can find it . . .



  9. #45
    Member Khalid's Avatar
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    Quote Originally Posted by Joe S. View Post
    Have you committed your Project to a PC board yet or are you still using a breadboard to prototype it? Those breadboards that you just push in the parts have tons of stray capacitance and, also; suffer with corrosion issues if they are old. I try to replace them yearly. Regarding your 33 vs 15 µF caps on the crystals, again the breadboards tend to add capacitance and is why you had to reduce the value, when using the PC board you will likely have to go back to the 33 µF units. You know, I have heard of nearby fluorescent lights causing them to act up too.
    Another thought the 16F628 is not the same as the 16F628A so be sure your compiler is set to the correct one. I am going to back in this thread to find the source code and see what it is telling the chip to do, if I can find it . . .
    I have etched the board as per the PCB layout provided by Alan... After etching i checked the continuity and shorts in the whole circuit and found no observations... Then i drilled the PCB and installed all the Jumpers and check each jumper for continuity... Nothing found all Okay.. After placing and soldering all components i again checked the continuity shorts from solder to solder and all very well...
    This is not my first experience of etching, drilling and soldering of PCBs, i have done a lot in past...
    Attach is the source code , schematic by Alan for your review please.

    Attached Thumbnails Attached Thumbnails Reversed Logic voltage to PICSTEP- What component to be replaced?-picstep-jpg  
    Attached Files Attached Files
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    Quote Originally Posted by Khalid View Post
    I have etched the board as per the PCB layout provided by Alan... After etching i checked the continuity and shorts in the whole circuit and found no observations... Then i drilled the PCB and installed all the Jumpers and check each jumper for continuity... Nothing found all Okay.. After placing and soldering all components i again checked the continuity shorts from solder to solder and all very well...
    This is not my first experience of etching, drilling and soldering of PCBs, i have done a lot in past...
    Attach is the source code , schematic by Alan for your review please.
    Hi Khalid,
    I mean no disrespect, I know you are adept at pc boards as I briefly visited your website, I did Not know if you made one yet, and I never open ZIP files from individuals, sorry. So do you have All inputs pulled up or down as is appropriate to their operating use? Do you have the comparators shut off CMCON = 7 ? Analog functions scramble your best efforts to use digital outputs and the power on defaults are always analog.



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    Quote Originally Posted by Khalid View Post
    I will definitely go to change of Power Supply and shall use LM7809 for input Logic supply to board. I will also try the whole setup with BOB and Mach3.
    Is this a typo ? LM7809 outputs 9v, LM7805 outputs 5v. Or am I seeing more than I understand ?
    EDIT:
    Ok now I have read the code, all in assembly, should execute fast. I have studied the pc layout too and see you DO have a bypass cap on the power in, very good, it seems you Are having oscillator problems, try reprogramming using the correct 16F628A chip selected (tedious I know) but there ARE subtle differences internally even within PIC families that will make your day very long and arduous. Be really certain as to the Quality of the ground going to the crystal and 3 caps. Unless it is a really time critical program I prefer the ceramic resonators with built in caps, as some of the Chinese crystals are of questionable quality. + resonators are cheaper than QUALITY crystals. When using resonators ALWAYS set to HS_OSC as they like a bit more power than crystals, regardless of operating frequency, as per the Data sheet. Check the PIC outputs for their ON STATE voltage with and without the finger. Sometimes it's easier to figure out what is NOT the problem until the problem is all that's left.

    Last edited by Joe S.; 10-12-2011 at 04:05 AM.


  12. #48
    Member Khalid's Avatar
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    Quote Originally Posted by Joe S. View Post
    Is this a typo ? LM7809 outputs 9v, LM7805 outputs 5v. Or am I seeing more than I understand ?
    I feel no disrespect as you were guiding me ... I appreciate your response about the Breadboard..This thread is not read by me alone but it will be read by thousand of newbies in future..your comments about using breadboard might be useful for them
    Its Type..I will use LM7805
    Thanks for correction... Here is the attached ASM code...

    Attached Thumbnails Attached Thumbnails Reversed Logic voltage to PICSTEP- What component to be replaced?-picstep_v4_0_schema-pdf   Reversed Logic voltage to PICSTEP- What component to be replaced?-picstep_v4_0_overlay-jpg  
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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Reversed Logic voltage to PICSTEP- What component to be replaced?

Reversed Logic voltage to PICSTEP- What component to be replaced?

Reversed Logic voltage to PICSTEP- What component to be replaced?