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???
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???
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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.
Hi Joe,
Thank you for your valuable advice.. I am still puzzled many peoples around having working PICSteps...How and Why?
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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.
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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.
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.
I feel no disrespect as you were guiding me:cheers: ... 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:idea:
Its Type..I will use LM7805
Thanks for correction... Here is the attached ASM code...
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The config bits are set as per your ASM source file and you should see them set in your HEX file as I explained earlier.
The MCLR is pulled up if it is NOT used, but your program sets it as an input it is looking for status of J2
According to the source file the PIC is set to 628a version and the compiler is reflecting that in the HEX listing.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
When I read the source file earlier I assumed the step rate was just software set, but I see by the schematic it was also referring the inputs for the external jumpers hardware setting. They have pull-up resistors when the jumpers are open.
What do you have them set for BTW?
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Hi Al,
I have checked with all the 4-combination of Jumpers J1 and J2. Nothing worked for me.. Currently i am fabricating the Phil 4-axes BOB to test the PICStep.
I have seen too many Hex files given by the Alan for programming the Chip. The names of the Hex are confusing can you decode for me please (Although i have almost loaded /erased/loaded all of the Hex files one by one without any fruitful results)
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Do you want the source file assembled in the link post #14?
https://github.com/alangarf/picstep
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Al, I think ALAN has posted the source file for V3 in the above link. Can you please compile and send me the HEX file.
Regards
PS:
I will check your posted TEST HEX file as soon my BOB is ready (probably tonight the BOB will be finished).
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Here is the HEX file from the source file in the link.
(re-name from txt to hex)
If you load MPLAB and build using the wizard, you just need the ASM and 16F628A.INC file, but select re-locatable assemble not absolute code when asked.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Khalid,
This is likely to be the first of many posts. I am going to try to diagnose the issues little by little, so I will need you to try certain circuit configurations with the parts you have, and maybe others.
Disclaimer: Please understand that I am neither responsible nor liable for any actions or harm caused...
The first thing you need to do is get rid of the 33pf capacitors for the crystal. Those will NOT work with the PIC you are trying to use.:nono: With a 20MHz Crystal (classified as HS), you MUST use 15-30pF capacitors. I recommend a capacitor in the middle of that range, such as 20pf.
Lets start with the most basic electronic components and move up to the most difficult.
The second thing I think you should do is mess with the driver section of the circuit. It is worrying that you can't get the motor to engage at all...
So here is what I want you to do: Remove the PIC from the IC socket. Using quite a few jumper wires, construct the attached schematic by putting wires into the corresponding slots in the PIC IC slots. For instance, you should connect a +5v wire to pins 4,6,7,8 of the PIC IC socket, where the IC used to be, etc. Do all of that except for the direction pin. Now, with all the wires connected as I have laid them out in the schematic, spin the motor. It should still move freely. Now attach the direction pin marked as a red switch in the schematic, (RB6, pin 12 on the IC socket) to the +5V source. The motor should now lock or resist you turning it.
Remember to disconnect resistor R9 in the original schematic.
If that test is successful, that means that the problem is likely with the PIC or a wire mishap.
If the test was unsuccessful, your driver chips may be blown, bad stepper, bad driver wiring, or I may have read the datasheet wrong.
Also, please attach a picture (or two please) of the underside of the board.
Other Questions:
- Do you have spare LEDs and 100 - 200 ohm resistors?
- Have you completed the LED Flasher project you talked about in post #29? It would be good if you did.
- You do have an ohm meter, correct?
- What is the amperage ratings on your +5V and +24V supplies?
Well it is very late now... I will post again tomorrow after you have tried the above.
Thank you for the detailed reply and procedure. I have some comments:
1- I have used 33PF then 27PF and now using 12PF with no good response.
2- Currently 15PF are installed across the 20MHz xtal.
I have some questions for you regarding the circuit:
1- Are you talking placing jumpers in PIC IC socket or the LMD??? As your attached schematic shows LMD Pin Out..
2- Is it possible if you can mark on the attached picture where i installed jumper and what Resistor i remove..
Point wise Answers for your Questions:
1- yes I have LEDS and 100, 220ohm resistors.
2-No i didn't ..
3- yes I have Multimeter that includes Ohmmeter...
4- +5V supply is ATX power supply and it has more than 6 Amp. where as +24V supply has 3 Amp.. I am using 1.2 Amp motor.(single Motor)
PS:
Frankly speaking i am fed up with this PICSTEP.. I have assembled the three boards and no-one work
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Yes, 15pf is good. Continue using those. Don't waste your time with the others.
- Answers:
- Jumpers go into the PIC IC socket where the PIC used to be. Since you have 'supposedly' correctly connected the PIC IC socket to the LMD driver, this will be a good test of those existing connectioons. You will not put jumpers into every pin of the PIC IC socket.
- Sure. Give me two pictures then: A close up of the IC socket with the surrounding components visible (~20mm away from the edges) and one near the LMD drivers. I will Photoshop the connections in for you.
Also, please attach a picture of the underside of the board as I asked in the last post when you can.