Down and dirty way to use a SMD PIC with a DIP programmer?

[bartman]

I want to use a couple SMD PICS for a small project.

I don't think I want to learn the ins-and-outs of in-circuit programming at this time to do this, but I do only have space for the SMD size of a 12F629.

I am wondering if this would be possible.

http://arieselec.com/products/18010.pdf

Take this adapter and temporarily stick the SMD PIC on it then put it in my programmer.

Any problems with this? Like I say, I would only be doing a couple of these as normally I can use the DIP versions for what I do.

Doable?

Thanks.

Bart

[Dave]

bartman, What I have done in the past is use a machined pin dip socket and solder a piece of ribbon cable to it (5 wires) and then on the other end use an inline connector which goes to the pcb I have the surface mounted processor on. this is usually the final product and I only use the "interum" cable to load a bootload hex file into the target processor. After which time I use the bootloader software to load the application and any serial activity thru an RS-232 port. No need to buy an expensive smd to dip adapter just for testing. If you have a look at the data sheet for the device you are trying to program it will show you the proper connections for ICSP. It's very easy...

Dave Purola,

[bartman]

Thanks, but I would have to classify this as the "not something I want to get into" reason.

It all sounds so simple if you know what you're doing, and I don't think I can be accused of that, but I need to design around this tempoary connection, understand what the heck you're talking about with bootloading and buy those connectors so I don't know if I am really saving any time or money.

I'm still a newbie here and probably in over my head half the time too!

Bart

[Bruce]

It's very do-able. I've programmed hundreds of 8-pin SOIC parts using a similar adapter in our programmers ZIF socket.

I press & hold the part on the adapter with a vacume pencil then click program. Real easy & super fast.

[bartman]

That's perfect then. I should be able to hold one for 30 seconds!

Thanks.

Bart

[mister_e]

you can even use a clip on adapter then solder each wire to a regular dip socket.

Now you just have to clip your PIC in the adapter then press program. I do it every day when i want to read EEPROM dump in my radio decode purpose.

I talk about that kind of adapter... 3M do some great. Even you can found some in overstock places.
<img src=http://www.picbasic.co.uk/forum/attachment.php?attachmentid=689&stc=1&d=1135995023 >

ICSP is another way to go when design permit. No big money adapter needed. Only 4 testpoint on your target PCB. Then you use 4 wires from your programmer to your target PCB.

[bartman]

That's a cool looking... thing. Would it also work on the clothes line?? :-)

Bart

[mister_e]

Would it also work on the clothes line?? :-)

Sure a bit expensive but could work. You know, i use some obsolete or 'too old' PIC on my pin board now... so why not using a test clip on a clothes line

3M do good one, but there's few other brand. Look digikey catalog or local supplier. I really like this method and, as i said, i use it daily to read/write from/to radio EEPROM when there's no testpoint on the PCB OR when the design do not permit to clip over them to read/write to them.

[bartman]

I found the clip in the Digi-Key catalog. It's about twice the money of the adapter.

Are you saying that I would just build my circuit with the SMD PIC in place then clamp this on and program that way?

I would solder the ribbon cable from each pin on the clip to the corresponding pins on a DIP socket, no other parts required?

What if I have not so great solder connections on my board and the clip doesn't fit well? Odds are they are not going to be fantastic joints with a tiny amount of solder. I don't have the proper equipment to make such a nice joint on something so small.

Bart

[Zeke]

I've done this with a 12F629 also. I just used the adapter that you show (or similar) that I picked up at Digi-key for about $8 CDN and held it down with a pencil while programming. I did end up soldering it to the adapter so that I could set it up in a prototype board which made it easier to re-program (over and over again!). When I was done, I just de-soldered it and put it in to my final circuit.

Good Luck!

[mister_e]

Well i was talking about to use that clip to program your PIC while not on the PCB ... to program before soldering on the PCB for the final step....but it could work... maybe not for the reason you said.

SO you can even leave some testpoint (or programming points... ) on the PCB, then solder few wire wich will goes directly to your programmer. That's more than feasable and allow to update your program if it needs to... one day or another.

[bartman]

Okay, but if I didn't have room for the programming points would this clip work to program something right on the board or does that kind of in-circuit programing require extra hardware in the cable to work properly?

IF it is just a matter of going pin to pin from the programmer to the clip and it is somewhat forgiving on the soldering this may be a good idea for me instead of the adapter.

BUT if it takes a bunch of extra parts to make it work other than the clip then the adapter is still my best bet.

Bart

[Darrel Taylor]

Steve's picture looked familiar. So I thought I'd show my programming cable for 12F629/675/683 etc.
The molex end plugs into my EPIC programmer

You can just stick the chip in it directly.

Or clip it on a chip on a PC board.

Works great.
<br>

[bbarney]

Now you guy's got me wanting one too.So what would be the best size clip to get to cover most every chip.A 16 pin Clip ?

[bartman]

Okay, so no extra parts and I can do this right on my board without affecting anything on that board like buzzers or LED's, etc.?

Just clip and go.

I like that.

Bart

[Darrel Taylor]

bartman,

Well, it's almost that easy. But, the circuit still has to be designed to not interfere with the ICSP signals. In the third picture, behind the clip, you can almost see a 3 position dip switch. With all switches open, the ICSP pins are disconnected from the rest of the circuit. Then during normal operation, the switches serve as Mode Select inputs.

That's just one way, though. You can do it without switches, as long as there are good sized resistors inbetween the pins and the rest of the circuit, and not much capacitance.



bbarney,

Good question ...

<br>

[bartman]

Thanks. I won't have room for any kind of switch, but then got to thinking the clip might still be best for me anyway. I can program it then plug the DIP into my breadboard to ensure the program works before soldering the PIC into place and finding out it was having issues then. Future projects will probably have more space to do it properly.

Bart

[Darrel Taylor]

Perfect! I think that's what Steve had in mind too. Post #6



P.S. I found that clip in a junk bin at the local electronics store. They wanted $2.00 for it.
Decisions that easy, don't come along very often.
<br>

[bartman]

To be lucky to have such a store here!

Bart

[mister_e]

Now you guy's got me wanting one too.So what would be the best size clip to get to cover most every chip.A 16 pin Clip ?

I have one for each model. Not cheap but decrease the chance to do mistake. BUT the ICSP connector or 'test-point' is still the cheapest way.

[bbarney]

thank's Mister E
Bart here'a a good pdf on smd part sizes,might help you out

[RossWaddell]

Steve's picture looked familiar. So I thought I'd show my programming cable for 12F629/675/683 etc.
The molex end plugs into my EPIC programmer

You can just stick the chip in it directly.

Or clip it on a chip on a PC board.

Works great.
<br>

I have a project which could benefit from using SMD PICs as the space the board needs to go into my model is quite tight. I've found the 3M clip at DigiKey but I'm unclear as to which pins I need to wire to program. I have an EPIC USB MEL so I'm presuming I can just remove my ZIF for regular DIPs and plug in the Molex connectors to the programmer, but it would be a big help if someone could tell which pins go where (for the 8-pin PIC above, it looks like the wires are connected to the PIC pins 1 & 2 and 5 & 8 - is that right?

If reviving this old thread is bad manners, I'll start a new one.

[Darrel Taylor]

There are 5 wires on that clip.
But if your circuit is powered externally, you don't need VDD.

[RossWaddell]

Thanks Darrel! Can I assume that J3 plugs into the melabs U2 Programmer's socket and U1 is the clip?

[Darrel Taylor]

That's a good assumption, yes.

[Charlie]

Also note you need to lay out your board so the chip clip has room to actually clamp on the device. No decoupling caps or anything too close by. It takes more room than you think... well, more than I thought, back when they were popular. I sure didn't learn that one the hard way, no sir

[RossWaddell]

Thanks Charlie! That's good advice as I'm not very good at desoldering (even with wicks) so being able to reprogram in-circuit is critical.

[AvionicsMaster1]

As Darrel said, make sure you design to accomodate the ICSP through switches or high resistances between PIC and load. The old PBP manual had some values of resistors but I couldn't find it in the PBP3 manual after a quick search. I've experienced thinking I could program once the PIC is installed only to find out I didn't fully think it through. Good luck.

[RossWaddell]

What constitutes high resistances? All the outputs will be connected to 150-220 ohm resistors (for LEDs) but there won't be anything on VDD/VSS. And which of the ICSP connections on the PIC are the important ones for this?

[AvionicsMaster1]

If you've got a PBP2.6 manual I recollect there are hard numbers in it for isolation resistance. I thought the desired value from the old manual was several hundred kohms but I don't see it in the PBP3 manual.

If you look here http://ww1.microchip.com/downloads/e...es/_91017b.pdf it says 1kohm isn't enough. I have found an LED to ground on the PGC or PGD pins, even with current limit resistor, causes problems. I also remember that a capacitor on the MCLR pin caused a problem.

Just FYI, all these recollections may not be relevant to what you're designing. From experience I now use a switch to disconnect the PGC/PGD and depending on use the MCLR pin from the circuit for ICSP. You can get surface mount components that are very tiny.

[RossWaddell]

If you've got a PBP2.6 manual I recollect there are hard numbers in it for isolation resistance. I thought the desired value from the old manual was several hundred kohms but I don't see it in the PBP3 manual.

If you look here http://ww1.microchip.com/downloads/e...es/_91017b.pdf it says 1kohm isn't enough. I have found an LED to ground on the PGC or PGD pins, even with current limit resistor, causes problems. I also remember that a capacitor on the MCLR pin caused a problem.

Just FYI, all these recollections may not be relevant to what you're designing. From experience I now use a switch to disconnect the PGC/PGD and depending on use the MCLR pin from the circuit for ICSP. You can get surface mount components that are very tiny.

Could you please point me to the surface mount switches you're referring to?

[AvionicsMaster1]

These are pretty tiny. If designed properly you will probably only need to switch PGC and PGD lines. This DPDT http://www.newark.com/knitter-switch...smd/dp/38K5668will do that.

This may not meet your needs exactly but there are thousands to choose from.

[RossWaddell]

Thank you!

[Waneta]

This looks very cool

[RossWaddell]

I wired up the 3M clip this afternoon and I successfully programmed a SOIC-8 12F683 chip. Huzzah! The only problem I encountered is the spring on the clip is strong enough to deform the chip's pins, so it won't sit flush on the PCB unless I straighten them out. Has anyone else seen this? Should I just work the clip over and over to reduce the spring tension, or is it just a question of holding the chip just right when closing the clip?

I marked pin1 with a white dot:

[Darrel Taylor]

Never had that problem with my clip.

But looking at the pictures ... yours seems to have one more loop in the spring. 7 vs. 6.
hard to tell though.

Maybe you could cut some off the spring.

[RossWaddell]

I just realized I'm using the wrong orientation of pins on the clip if I want to do ICSP. Perhaps after I switch them the pressure won't be so bad.

[RossWaddell]

I re-wired the clip this morning (flipping the orientation of pin1) and it works! It's a bit tricky seating the SMD properly to make contact but it doesn't bend the pins (because they sit over top of the clip's metal pins).