Issues with JDM and other homebrew PIC programmers.

Thread Starter

mikejp56

Joined Jun 14, 2015
70
Hi be80be,
I have a question about the programmer. I would think that all I would need is the USB connections and the crystal and caps for PICkit 2 to detect the programmer. Is this a valid assumption? I want to try to re-use a breadboard that was used for a different USB project, and I have the 4 USB connections and the crystal and caps correct. I can see oscillations on one pin of the cap, and I see a short burst of USN activity when I connect the USB connector to the board. However Windows device manager says that there is an unknown device connected, and PICkit 2 does not detect the programmer. What would be the bare minimum circuitry needed for PICkit 2 to detect the programmer, not necessarily to actually program?
Regards,
mike
 

be80be

Joined Jul 5, 2008
2,072
You have to have a cap on the VUSB a 224 will work or you'll get a programer not found.
And double check the D+ and D- they are to easy to get backwards.
 

Thread Starter

mikejp56

Joined Jun 14, 2015
70
Hi be80be,
I think that I have a thread closing post! The reason for my last question, the one about detecting the programmer, was because I had built the HW for the USB PICProg from usbpicprog.org. I was sure that it was wired correctly, but it always gave unknown device error messages and no programmer detected messages. I went so far as to use the highliter and ohmmeter method of verifying my wiring; all was good.
So I thought that the FW was crap; that is when I decided to try out your circuit. I burned the FW into a chip using my trusty JDM serial port programmer, and got the same error message from Windows. This got me to thinking that the HW was the problem. After reading the forum at usbpicprog.org several times and poring over the schematic till my eyes were bleeding, I remembered something from when I was wiring the board up. A reader of the forum had posted that the D+ and D- lines from the USB connector to the 18F2550 were reversed , but the board op had said that the error was cleared up. So I just swapped pins 15 and 16 and VOILA, drivers were loading and the programmer was detected! I was able to detect and program all of the various PICs at my disposal. THE DAMN THING WORKS! Sorry for shouting!
So I have used a homebrew JDM (serial port) programmer on a desktop, NOT a laptop, to program 12F, 16F, and 18F series PICS. I have also used a homebrew USB programmer to program those same families. Both programmers were built using point to point wiring on perfboard. You old schoolers will know what point to point wiring is. The construction of these 2 programmers shows that it is not hard to do, but care must be taken to ensure proper wiring and firmware is used.
In closing just let me say that I am an old school guy; I prefer to build my own stuff where possible, and this was definitely possible.
Cheers, and I hope my experience will encourage others to build their own.
Regards,
mike
 

be80be

Joined Jul 5, 2008
2,072
Mike your speeking to choir Mike but that opens up worms LOL I've programmed pic's from just serial port an 3 resistors but not everyone has that luck and I've made some good jdm programmers The pickit2 clone I like the best. I have made them on bread board and they work.

But I told you watch the D- and the D+ pins and the cap on VUSB people get that wrong a lot when the draw it up LOL

Glade to see it works
 
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dannyf

Joined Sep 13, 2015
2,197
I prefer to build my own stuff where possible
It clearly can be a good and fun learning experience.

For me, however, tools (programmers + compilers + ides) are so vital to your exploration (and livelihood if so) that they should be the least place for you to doubt.

Because of that, I buy my pickit2s from Microchip.
 

Art

Joined Sep 10, 2007
806
I remember the days of this programmer works with this and the other programmer works with that,
and then the next thing you know....


 

be80be

Joined Jul 5, 2008
2,072
I remember the days of this programmer works with this and the other programmer works with that,
and then the next thing you know....


Lol its still like that they made the great pickt2 now you need pickit 3 next you'll need a pickit 4 it never ends
 

ErnieM

Joined Apr 24, 2011
8,377
(Building programmers) clearly can be a good and fun learning experience.

For me, however, tools (programmers + compilers + ides) are so vital to your exploration (and livelihood if so) that they should be the least place for you to doubt.

Because of that, I buy my pickit2s from Microchip.
I too want my programmer to be bulletproof.

Good lord, did you really spend two months wiring up a programmer that cannot do in circuit debugging?

For 10 bucks, you can get a PICkit II off EBay. Even with free shipping they rarely take more than 2 weeks to arrive, 3 on the outside. 30 bucks gets you a PICkit III.
 

be80be

Joined Jul 5, 2008
2,072
I don't no witch was made the programmers I made can debug there clones of the pickit2. I made mine back when bill came out with his junebug clone. It works just as good as a real pickit2 I know I own one of them.
 

dannyf

Joined Sep 13, 2015
2,197
I made mine back when bill came out with his junebug clone. It works just as good as a real pickit2 I know I own one of them.
I just looked at junebug now and it looks like a clone of pickit2, with identical pin-out, and skimmed on some non-essential parts.

Does anyone now if the firmware is the same, binary- or source code-wise?
 

be80be

Joined Jul 5, 2008
2,072
I really think the pickit2 is one of the best I made mine after studying there sch for a day or two. First one wouldn't program a chip lol I used to big of inductor. I Made it on breadboard with parts I found on old boards. But I have 3 of my own that I use all the time they actually work better then the real pickit2 I have there voltage levels are better.
 

dannyf

Joined Sep 13, 2015
2,197
The complication with pickit2/3 is the vpp generator. If you accept the limitation to low voltage programming only (all the newer chips), you can make a pick it with just the chip plus passives.
 

be80be

Joined Jul 5, 2008
2,072
I don't have any problems with VPP after I figured how the charge pump works. I've even added chips to the pickit2. Microchip could of keep adding chips too, Guess they wan't to sell something else. And as far as debugging goes you can't debug every chip without buying something else that even goes for IDC2 and I sure it's the same with the pickit3 and IDC3.
 

ErnieM

Joined Apr 24, 2011
8,377
I don't have any problems with VPP after I figured how the charge pump works. I've even added chips to the pickit2. Microchip could of keep adding chips too, Guess they wan't to sell something else. And as far as debugging goes you can't debug every chip without buying something else that even goes for IDC2 and I sure it's the same with the pickit3 and IDC3.
With some very few exception for the smallest of devices this is utterly and completely false.

The large majority of devices can be debugged in circuit with a PICkit II or an ICD 2 or 3. The now obsolete PICkit II does a decent job on the subset of devices it supports too.The same connections to program a PIC may be used to debug it, no hardware required.

For those devices that do not include the debug hardware there are inexpensive hardware equivalents available. While the form factor is quite different they strive to be very similar electrically.
 

be80be

Joined Jul 5, 2008
2,072
So you don't need headers that cost more then the programmer debug a 16f690 or a 16f628 for starters. It's not untrue you have to make sure the chips you use can be debuged easy or its going to take more then just the tool you have to debug. II have 20 chips I use only two can be debuged with a pickit2 alone that don't look to false to me lol.
 
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be80be

Joined Jul 5, 2008
2,072
Yep it looks totally untrue to me lol maybe I'm just unlucky lol.


Some 8-, 14- and 18-pin devices use small header boards with a special MCU for debugging. This special MCU has extra pins for PICkit 3 communication and therefore allows the use of all pins on the part for the application. The header board is not used or needed for programming. However, when debugging these devices the header must be used. See the "Header Specification" document below.
 
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