Help me debug my PICKIT2 clone....

[annna]

ignoring all those errors if I try to detect my other 18f2550 connected to pickit2 I gives me error "No device detected".... Why is that so........

---------- Post added at 20:59 ---------- Previous post was at 20:47 ----------

I checked for R3 no break or dry solder...
and Q1 replaced still same problem...

 

[qwertyuiop415263]

if your pickit2 is not detected its mean either you didn't program it with bootloader or you usb connection D- and D+ are wrong.

 

[mvs sarma]

annna , has already crossed that stage. Now his Pickit is detected.
Generally the Vdd and Vpp should be available as switched by the micro. In this design, without any control, Vdd is available on the Output. the Micro, surely feels that there is some external voltage. The original hardware diagram has facility for controlling these conditions. and many other clones have not disabled but this Design has made the Vdd directly available at the icsp output with no control.

Perhaps the best would be to make a full fledged one and getting few P and N Mosfets should not be an issue. I recollect the post a that was started by computerman29 and he and many of us were able to make and use it.

 

[pranam77]

Vpp error will be caused by Transistor associated with the 680mh coil and associated componenets. Also cross check which transistors have you used and thier pin assignments and orientation as these tend to differ. The firmware chip gets a feedback from the Vpp via a resistor divider network built arround two resistors (sorry i dont have acess to the circuit now)..check that part too.
Cheers

 

[mvs sarma]

Yes, i agree with Pranam77 .
as per the schematic, R4 and R5 , check whether the values were interchanged while assembling. If so, perhaps the Vpp could be lower.

 

[PA3040]

Does your programmer have more components or just only device with zip socket

 

[annna]

Here I am with these results while troubleshooting....

1. external Vdd detected... (which is not a problem as you guys said)..

2. Vpp -- the software shows it to be 12.00volts.. but there is not a single point on my circuit where voltage crosses 5.38 volts when checked using a multimeter... and when I push MCLR on button on the gui I receive 3.23volts on pin 1 and when pushed MCLR off it jumps to 4.3volts...

3. Data and Clock pins are working as they should...

So what do you guys say.... I think its Vpp one thats causing problem...

 

[mvs sarma]

check as i told at post 25, whether R4 and R5 locations interchanged?

 

[annna]

no R4 and R5 are in right positions... here is voltage drop on R5 at different positions..

1. at normal position (MCLR off)... 3.58 volts

2. when Vpp tested to be 12.0 volts it is 4.47..

3. and when MCLR on it is 2.98 volts....

while total drop on voltage divider R4 and R5 is 5.23 volts....

 

[mvs sarma]

now the only way is to make one here
btw, please indicate the link where you got this sch?

 

[annna]

there is not much info given on this site.... But I found the schematic here... and made it for its simplicity...

Rough-pad « Rabiul's

 

[mvs sarma]

annna, did you see the note which reads as under:
"Note:

I have used the inductor of unknown value (no label on it, and having no LC meter). I have used some components with different value comparing to some other schematics found on the web. For instance I have not used a schottky or any diode on ICSP header pin # 2 (VDD), as using a diode gives me error. If you get VPP error you may replace the value of R3 to 2.7K (I used 2.2K) or value of C1 to 47uF (I used 10uF). You may also use the capacitor C7 of 10uF, while mine is 100uF – this is not much important. Anyway, if you really get VPP error, try changing the value of R3, then try with changing value of C1. The one I made is working and ok for me. But I can’t assure that this will also work for you. If you have any other schematic/PCB which works OK, and you have all the parts exactly as mentioned in the schematic, I recommend you to build that one instead of this."

 

[annna]

tried these above suggestions as well... but no difference on Vpp voltage... I can not get the point how can Vpp be 12 volts when usb port supplies only 5 volts...

another thing won't 12 volts damage my controller..

I think my circuit is working except that 12 volt part... So can you tell me where does 5 volts from USB jumps to 12 volts... that may help me debug....

 

[mvs sarma]

there is a dc to dc converter using software , Q1, L1 and D1 etc. R4, R5 divider supervises the actual value at the output. 12V Vpp is needed for programming the PIC chips.

 

[PA3040]

Let we know the value of the R16 resistor

 

[mvs sarma]

@Annna, please replace the Q1 and / or check proper pin placement. For me after assembling, the circuit is measuring Vpp around 11.6V DC at pin1 of icsp. Actual programming needs to be checked.

@PA3040, R16 is 100 ohms

I have checked and it is programming PIC16F628A correctly. Now, it is for Annna to check whether the transistors are OK and whether they are placed properly as per the pin out for the devices used. All the best.....

 

[annna]

ok I shall try....... Just tell me what value inductor have you used....

 

[mvs sarma]

if you have used 820uH, it is ok you can continue. As I suggested earlier, try to add a 10 ohm resistor in series to the inductor before connecting to 5V.
i can very well suspect the transistors' failure. check them with a dmm if o you know, otherwise rep0lace new ones, take due care of pin out.

PS: I had used 680uH as Bought few such.

 

[PA3040]

ok I shall try....... Just tell me what value inductor have you used....

Try with this to rectify the problem. this is design by myself and tested

 

[mvs sarma]

The artwork appears Nice PA3040 !! However, as annna has already assembled one, let us make it work. The same circuit i had assembled, and is working for me. It helps him save time in again making a fresh design.