want input on idea: ZIF socket daughtercard for STK500

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On the last AVR project I did, I got tired of the difficulty of ripping AVRs out of the STK500 programmer. Especially with the 40-pin chips, it seems I can't really do it without bunging up the socket beneath the chip ,slightly prying the chip up enough so my IC puller will work, and in any case it has always been very difficult getting the chips in and out.

I fashioned a 6 pin header on my latest circuit, so that of course cuts down somewhat on the need to pry, but I though to myself:

why struggle? I can easily make an add-on daughter card like the stk501 that has a couple really nice Aries ZIF sockets on it. I can use the EXPAND connectors. I can fit two of the 48-ping ZIFs on the board, and I should be able to support with one socket the "A3" chips like the 8535, m16, m323, m8535, m32 (using the first 20 rows of a 48-pin socket), and the "D1" series like 2343, T12, T22, T11, T45 et all (using the other 4 rows), and with the other socket, in a similar fashion the 2313 (my favorite), and the m8 (which I have never used). I could post the resulting ExpressPCB SCH and PCB files here on Avr Freaks for everyone to use.

What do you think of my idea?
Would you find it useful to have ZIF sockets for the STK500?
If you could download the layout and all for free, would you spring the 19 bucks apiece for 2 ZIF sockets for your board, as well as the perhaps $20 per board?
Is the STK500 going to be around for a while?
Am I planning on supporting the right AVR chips? I could probably make the layout handle the other chips too in the same board run by combining two entirely separate layouts on the same PCB.
Any other ideas for me? Do you want the SPROG headers on the daughter? (I was planning on making the board as big only as the target section itself).

Typing to you from my Sun keyboard plugged through an AVR board I made into my PC,

Todd Cromwell III
Seattle

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P.S. I already have half the schematic drawn up in only a couple hours. This ExpressPCB toolchain is good. Now if I can figure out what to use for AVTG . . .

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Only since you are asking, I wouldn't need such a device though it's great you are doing one. Others might want it.

I think a lot of us use ISP programming and the header pins pretty much exclusively. All my designs use surface mount parts and I program them in place.

Please note - this post may not present all information available on a subject.

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An approach that is crude but effective is to put more sockets into the STK500 sockets. [There are some past threads beating this to death.] At that point, there are several alternatives:

--Keep your "dev" AVR chip in it's own private dev (spare) socket. Then when you move from programming on the STK500 to your app, if any pins get munged up it will be on the inexpensive socket;
-- and/or adding extra socket(s) on the STK500 raises the target chip, and makes it much easier to get a good angle for insertion or removal;
-- and/or adding extra socket(s) on the STK500 raises the level so it is much easier to accomodate a ZIF socket.

But we are with refields at our place--we allow for ISP in almost all of our apps, and would probably never use an adapter of that type even for DIP designs.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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You could make a daughterboard that would fit all AVRs in DIL package up to 40 pins. You connect the daughterboard via the EXPAND0 and EXPAND1 connectors as You envisioned. The signals go from there to a 40 pin header (2 rows of 20, similar to the 2x10s on the STK500). Adjacent to that You have eight 2x20 that connects to a 40 pin universal ZIP (one that accepts both .300 and .600 DILs, $20 or so at Jameco). These different headers "corresponds" to the eight sockets on the STK500, they route the appropriate signals to the ZIF socket. Now You select the pinout of the ZIF by connecting the incoming 2x20 to the appropriate one going to the ZIF with an IDE-cable (an operation much less nerve-breaking than prying at the STK500 sockets).

The idea was stolen from a GAL-programmer (GALblast) I looked at for a long time but never built.

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I appreciate your responses, thank you.

I think the reasons for pulling my chips out may be that I was trying out two
different AVR types (my latest board can use either of two), and I switch projects.
It's so unpleasant to take those 40 pin chips out. As I mentioned, my boards for the Sun Keyboard to PC project use the ISP header (it's fun!).

The double/triple/quad decker idea is a good one, and I have used that before, but
it seems a little crude and rickety, and you still have to unplug stuff if you switch procs (because the STK500 can take one only). The dev chip in its own socket is also a good idea.

The IDE cables idea with the multiple 2x20 headers could work well. Then I have to plug and unplug the IDE cables, though. And yeah, prying at the STK500 sockets is never-wracking, good description.

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ISP isn't that tough once you already have the STK500. Think about the objectives you just stated--multiple target flexibility and effort to swap the actual chip from programmer to target. ISP addresses these admirably. Once you use it, you'll never look back. The only tricky part is avoiding conflicts with the ISP signals if you use all the pins.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Reading this thread, I realized that I had a 40 pin TextTool ZIF socket in one of my parts drawers. Those who have been arround a while will remember them, their the ugly green sockets with the lever located up by pin #1.

I was thinking about mounting them on my STK500. The problem is that, the body of the ZIF socket won't physically fit in between the option headers and the port headers, and if they did, the port header would intefere with the release handle on the ZIF socket.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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Hi,

Quote:
-- and/or adding extra socket(s) on the STK500 raises the level so it is much easier to accomodate a ZIF socket.

Isn't Lee's statement above alluding to a fix for this statement (below)?

Quote:
The problem is that, the body of the ZIF socket won't physically fit in between the option headers and the port headers, and if they did, the port header would intefere with the release handle on the ZIF socket.

Just wondering, I haven't tried it.

Regards,
Steve

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Yeah, I have used the ISP; that's how a reprogram my keyboard translator I made.
I just still find myself pulling the chips now and then, and it's a pain. I use the
STK500 with a breadboard, and there it's easy to use the target section on the
STK500 and put the port cable over to the breadboard, without hooking up the
ISP connections too. Also, I do sometimes get conflicts with the port on the ISP
connector depending on what circuit I am working on.

Those TexTool sockets I don't like very much. I like the black Aries ones, very
high quality. I did think about doing the "decker" solution, as I did years ago for a
Z80 development board I had, but as I said, I didn't like that solution much.

I am nearly done with the schematic and layout. I just need to handle the AVTG
and similar signals as called out in the STK500 schematic. Since I haven't
used that peripheral those weren't as trivial as the PAT0 etc signals.

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Hey,

As for ZIF sockets - I had a number of these cheapZIF sockets from the local electronics store. They didn't have handels, just kinda a little catch that you pulled up to release the chip. I don't really know how to explain it though.. when putting the chip in it automatically closed the ZIF.

At any rate they were about the same size as a normal IC socket, so they easily fit on the STK500. Myself I wouldn't bother with an add-on card, I either use ISP or just put it right in the STK500 when I am using the STK500 for dev.

-Colin

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I would think that, unless the STK500 is being used for production programming, there wouldn't be a huge need to frequently swap Uc's. I'm using the Mega16 for limited development and then moving over to the Mega32, which is what I seem to have setteled on for a base controller. This isn't to say that I wouldn't move up or down in performance, the Mega 32 seem to be about right for my needs.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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Heh heh, I just completed the schematics and layouts and sent the order for
the PCBs off to ExpressPCB.

Hopefully I didn't make any (big) mistakes.

If everything goes well I will have 2 daughtercards, one of which supports the most
common processors that go in 4 of the STK500 sockets, and the other supporting
the other 4 STK500 sockets.

If this works I will post the sch and pcb files to the site for others to use.
I realize that a lot of you see little use since you use ISP.

I use ISP too, but as I mentioned I still use the programmer itself to develop
on so I find myself ripping chips in and out all too often.