PicKit 3 Schematic in Eagle format.

[Computerman29]

Here we go again!!!

I drew the original PicKit 3 Schematic into Eagle. It is identical to the original in all but the following respects:

1) Test points have been omitted.

2) Memory chips have been substituted with SST parts

3) Q2 and Q3 have been substituted with Central Semiconductor parts.

4) The MOSFET'S have been substituted with ON Semiconductor parts.

Learning from my PicKit 2 project, I made my own library to avoid the MOSFET fiasco. (What a mess that was!!!) The subed parts could be easily changed back. I only changed them because I am on a very low budget, I can't get samples of Zetex or Fairchild, and Atmel is a pain to get samples. (At least in the USA)

As with the PK2 project, it would probably be only a few dollars more (maybe even cheaper) to buy an original, but I like to build things. :lol:

I have not started the layout yet. I wanted to get some feedback first. This will be much more of a challenge than the PK2, but still "do-able". It is done in all SMT devices, and the processor is .5mm pitch TQFP. All but the IC's could be done in TH, with the IC's soldered on the bottom. That would make it a bit easier to build and it would still be single-sided. The attached zip contains the schematic and the Eagle library of most of the parts used.

Opinions? Critiques? Suggestions?

 

[john blue]

Nice.. wating for people to build it XD.... you need the pickit 3 hex?

 

[bigdogguru]

Nice ...

I'm just starting to use Eagle and would like to see your layout when it's done. I'm sure I'll be able to pickup some pointers from your example. Eagerly awaiting the posting of your layout.

Thanks

 

[Computerman29]

Nice.. wating for people to build it XD.... you need the pickit 3 hex?

I'd imagine the hex is in the mplab folder like with the PK2 and ICD2

 

[boonserb]

Thank you. But pk2 hex can used to pk3 and it's no problem?

 

[Computerman29]

Thank you. But pk2 hex can used to pk3 and it's no problem?

The hex for the PK3 is in the same place as the hex for the PK2.

 

[john blue]

So, how's the layout? )

 

[boonserb]

The hex for the PK3 is in the same place as the hex for the PK2.

Thank you.

 

[Computerman29]

Finally started on the layout. Progress will be slow because I am preparing to move.

 

[jametzne]

Have you gotten validation that that SPI memory will work? My experiences shows that it won't, but I haven't yet dug into an alternative.

I have the SST25VF040B installed in my PicKit3 clone. The PicKit3 appears to want to do multi-byte writes using the 0x02 command without toggling the CE pin. (I think this is similar to the Microchip EEPROMs.)

Per the SST25VF040B datasheet, multi-byte writes don't look to be possible with the 0x02 command. When using the multi-byte write command, it still wants CE toggled after each byte.

I can post the SPI transactions or waveforms if they are of use to anyone.

Reference my other post:
Re: any body with clone pickit3 circuit and pcb

 

[jametzne]

Have you gotten validation that that SPI memory will work?

I found out the original PK3 used Microchip's 25LC256I SN for U3 and Atmel's 25DF041A SH for U4. I've validated that the 25LC256 part works fine as U3. Then I tested the W25X40BVDAIG part by Winbond in place of the Atmel part for U4 and the programmer-on-the go function worked as well (it was available in DIP which made testing easier). I was not able to get the SST part to work since it handles multi-byte writes differently than Atmel or Winbond. I'd recommend updating your board/schematics to not use the SST part. Although the Winbond part seemed to work OK for me now, I think I'd lean toward the Atmel part to match the original PK3.

 

[Computerman29]

Good idea. I only chose the SST part because I have them on hand. Since I have not built it yet (I have been busy packing, moving and unpacking), I will change it in the .sch/.brd files and repost. I will also change U3 to the Microchip part to match the original. I thought that they were both Atmel in the original otherwise I would have used the Microchip part. Thanks for pointing that out. Stay tuned...

 

[Computerman29]

As promised, here is the schematic and board files with the original Microchip and Atmel parts for U3 and U4. The layout is NOT complete, but included for reference.

 

[JayantD]

Computerman29,
Some comments on your schematic:
1. You need not place junctions on every pin.. use junctions only when two wires cross each other and are part of the same net. In case you are having problems making the nets, you may adjust your grid size accordingly.
2. Check for ERC errors and eliminate them.
3. Draw an outline for your schematic. See Frames library.

All the best for your project!

 

[Computerman29]

Thank you JayantD.

I know I don't need to, but I use junctions on every connection mainly to make sure they are connected properly when I check the nets. My design does have erc errors, but they are all the result of either unused pins on IC's, or because some IC's use GND, and some use Vss and they are connected together - Same thing with Vcc and Vdd. The outline is probably a good idea. I have never used one.

I have done some work on the layout. Honestly, I'm not sure I can do it single-sided, and I can't make double-sided boards myself. I have only an old clothes iron and press-n-peel blue film. HELP, PLEASE!!!

 

[whitelynx]

I have done some work on the layout. Honestly, I'm not sure I can do it single-sided, and I can't make double-sided boards myself. I have only an old clothes iron and press-n-peel blue film. HELP, PLEASE!!!

You can always do it single-sided... you may just need some jumpers to get the design completed. I'll take a look at the board files soon and see if I have any suggestions. I'm interested in building one of these and seeing how it works programming an 18F4550 and a 24FJ32GB004.

 

[Computerman29]

I have updated Eagle files.

All parts are now original or equivalent except Q3.
Resistors and ceramic caps are 0603.
Tantalum caps (except C23) are 0805.
The fuses are 1206.
The crystal could be changed to a smaller one.

The sizes for all but the IC's could be scaled back up to make it easier to build - perhaps even single-sided, but it will also cost more to have the board made if you don't make it yourself.

 

[fercho89]

Amazing work !! Thank you very much for sharing the schematic with us because yersterday at night my original Pickit 3 suffered a terrible damage.

I found something that i think could be useful for you. I look forward for your opinion.

Have a good day