Author Topic: How to program SOIC chips?  (Read 4128 times)

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Offline ConscriptedTopic starter

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How to program SOIC chips?
« on: January 18, 2011, 03:29:19 PM »
How do you program the micro if you want to use a SOIC chip and your design does not include header pins for IN-System programming? With a DIP I would put it in another board with a DIP socket and move it after programming. I can't seem to find something similar for an 8 pin attiny85 in soic format.

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Re: How to program SOIC chips?
« Reply #1 on: January 18, 2011, 04:05:02 PM »
This is just for one board, thats already soldered, right?

In that case, you'll have to solder 26 gauge wires to each individual pin you'd like to access.

Offline Soeren

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Re: How to program SOIC chips?
« Reply #2 on: January 18, 2011, 05:12:55 PM »
Hi,

How do you program the micro if you want to use a SOIC chip and your design does not include header pins for IN-System programming? With a DIP I would put it in another board with a DIP socket and move it after programming. I can't seem to find something similar for an 8 pin attiny85 in soic format.
Plenty of ZIF-sockets out there...  If you wanna part with the cash - $111,- for a multi socket from DigiKey (and that's really not expensive) and $50 for a more modest one from solarbotics

I program the PIC10F-series through a similar ZIF-socket.

Perhaps Atmel sells them along with their programming equipment and if not, MicroChipDirect does (or at least they used to).

The alternative is to design the board with pads (can be anywhere you can find room for them, or make the bed to fit directly over the pins) instead of pins, but you still need to use resistors to make the programmer able to "rape it".
Then you just make a "bed of nails" where the PCB goes down over correctly placed pogo pins, just like in ATE.
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Søren

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Offline Soeren

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Re: How to program SOIC chips?
« Reply #3 on: January 18, 2011, 05:21:12 PM »
Didn't study this page for more than a sec but it should be worth a wet dream.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline ConscriptedTopic starter

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Re: How to program SOIC chips?
« Reply #4 on: January 18, 2011, 09:52:39 PM »
Thanks Soeren. All of those options are more expensive then I have a budget for. I'll have to think of something. I do appreciate the time you spent.

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Offline Graynomad

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Re: How to program SOIC chips?
« Reply #5 on: January 19, 2011, 04:24:41 AM »
Is this a one-off? an existing PCB? Production environment? Only while developing the code?

What other circuitry is connected to the SPI pins?

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Offline ConscriptedTopic starter

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Re: How to program SOIC chips?
« Reply #6 on: January 19, 2011, 08:22:55 AM »
Yeah. This is a one off type of deal. I'm building something small and don't want to spend the space.

Offline Graynomad

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Re: How to program SOIC chips?
« Reply #7 on: January 19, 2011, 08:33:37 AM »
Wow it must be small if you can't afford a few pads.

In that case I don't think there's much option but solder a few wires on, although I think there are SMD chip clips that would be neater.

You still may have issues with contention on the signals.

Another thought, add the pads to the edge of the board, program the chip, then cut that part of the board off.
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Rob

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Offline Soeren

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Re: How to program SOIC chips?
« Reply #8 on: January 20, 2011, 11:25:16 AM »
Hi,

Thanks Soeren. All of those options are more expensive then I have a budget for.
A "bed of nails" can be made with a bit of Vero board and some cheap pogo pins - You could even make your own pseudo pogos, using just some piano steel wire (like a guitar string) or similar (I'll make you a drawing if you need it).

Whatever solution you choose, remember that the programming pins should be isolated from the rest of the circuit with resistors (say 5k upward), or the programmer will not have the power to control the lines.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline ConscriptedTopic starter

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Re: How to program SOIC chips?
« Reply #9 on: January 20, 2011, 05:37:14 PM »
A drawing would be great. I may have something similar in mind but would love some clarification.

Offline Afroman

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Re: How to program SOIC chips?
« Reply #10 on: January 21, 2011, 08:27:05 PM »

Offline ConscriptedTopic starter

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Re: How to program SOIC chips?
« Reply #11 on: January 21, 2011, 09:10:42 PM »
Very interesting. Thank you!

Offline Soeren

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Re: How to program SOIC chips?
« Reply #12 on: January 21, 2011, 10:40:37 PM »
Hi,

A drawing would be great. I may have something similar in mind but would love some clarification.
This is a rough scetch of how I envision it:

Not to (any) scale - check the metrics of your chip.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline ConscriptedTopic starter

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Re: How to program SOIC chips?
« Reply #13 on: January 22, 2011, 08:22:47 AM »
Hmmm. Interesting. I'll look into this too. Thanks for the extra effort

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