QFN programming

Thread Starter

Shizman

Joined Dec 2, 2008
7
Hi everyone,

Not researching sufficiently, I just bought:

PIC16F887-I/ML-ND (44QFN)


Now I have the problem of not knowing how to get my code onto it. I have a programmer for PIN-based chips, but this is different of course.

Everything I have found is VERY expensive to get my code onto the chip. Should I cut my losses and get a chip that's PIN or SOIC based?

Also, what socket can I use to actually put this on my IC?

Thanks!
 

RiJoRI

Joined Aug 15, 2007
536
Look into the PICKit2. One of the boards (the debug module) has an 887 chip already.

Also, I think there are DIY programming instructions for the re-programmable (F) chips. Check the uChip forum,

As to how they are programmed, usually it's in-circuit: the board has a 4-6 pin connector which goes into the PICKit's socket, and away you go! Of course, this is good only for limited-run boards: Plugging in a board, programming the chip, and unplugging the board 100 times gets boring very quickly!

HTH,
--Rich
 

Thread Starter

Shizman

Joined Dec 2, 2008
7
I actually have the Pic2Kit with its sample board, complete with PIC16F already attached. I think that's why I ordered another one, in hopes of being able to make my own board and then solder this new chip onto it.

Now I'm running into more questions that are difficult to find answers for:

1. Do I need to put my QFN chip in a socket before attaching it to my own PCB? If not, how do I attach/solder it?

2. Are the QFN chips really made for machine-soldering methods (i.e. should I just get a pin-based or SOIC IC?)

3. (Asked already above) How do I cheaply program this darn thing?

Thanks for any help you can give!
 

mik3

Joined Feb 4, 2008
4,843
I actually have the Pic2Kit with its sample board, complete with PIC16F already attached. I think that's why I ordered another one, in hopes of being able to make my own board and then solder this new chip onto it.

Now I'm running into more questions that are difficult to find answers for:

1. Do I need to put my QFN chip in a socket before attaching it to my own PCB? If not, how do I attach/solder it?

2. Are the QFN chips really made for machine-soldering methods (i.e. should I just get a pin-based or SOIC IC?)

3. (Asked already above) How do I cheaply program this darn thing?

Thanks for any help you can give!
1. Its better to use a socket because in case the chip burns you can replace it easily. Also, there is a chance to destroy the chip due to overheating while soldering.

2. Not really, but it is easier to work with DIPs than QFNs.

3. You can buy a DIP to QFN adaptor as the one you found in ebay.
 

Thread Starter

Shizman

Joined Dec 2, 2008
7
What socket should I use for the 44-pin QFN chip? Are there specific things I need to look for when shopping for this?

So the thing I showed you on eBay will allow programming of it? I have a 40-pin programmer, so I assume only a subset of the pins are needed for programming?
 

mik3

Joined Feb 4, 2008
4,843
What socket should I use for the 44-pin QFN chip? Are there specific things I need to look for when shopping for this?

So the thing I showed you on eBay will allow programming of it? I have a 40-pin programmer, so I assume only a subset of the pins are needed for programming?
Yes, just a few pins of the chip are used for programming. If you can identify them (datasheet) you can take a simple QFN socket and a few wires as to be able to connect the QFN pins (the ones only needed for programming) to the DIP socket.
 

Thread Starter

Shizman

Joined Dec 2, 2008
7
Yes, just a few pins of the chip are used for programming. If you can identify them (datasheet) you can take a simple QFN socket and a few wires as to be able to connect the QFN pins (the ones only needed for programming) to the DIP socket.
Ahh beautiful. Now, any idea where I can get a socket for this chip? I have tried looking in Digikey, but I have no idea what to look for. Are they called something other than a "socket"?
 

mik3

Joined Feb 4, 2008
4,843

RiJoRI

Joined Aug 15, 2007
536
The PICKit2 connects to ANY supported microcontroller in the same way, using 5 electrical connections:

* Vdd, or "supply voltage"
* Vss, power and signal return ("ground")
* MCLR/Vpp, the "reset pin"
* PGC, the ICSP clock
* PGD, the ICSP data
* (If your processor has the "low voltage ICSP option" you will need to make its "PGM" pin LO with a suitable pulldown resistance.)

These 5 signals appear on the 6-pin header socket on the PICKit2. Pinout details about the physical connections are in the documentation.

You must look at the Data Sheet for whatever processor you are working with, determine which processor pin(s) is used by each of these signals, and make the electrical connection. The details are up to you: a pin header on your PWB (or solderless breadboard) that mates directly to the PICKit2, a shop-built jumper cable, loose wires soldered directly to the
processor pins, etc. Don't let wire length get too long, and a 0.1 uF power supply bypass capacitor located near the chip may be helpful.

Commercial products that may help you with this task are discussed, illustrated, or linked from the recent thread "PICKIT2 OEM Boards".

Dale
So it actually seems quite simple!

--Rich
 
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