In circuit Programmer

J

jmumby

Senior Member
Hello,

Does any one know if there is a tool that will program chips insute like a SOIC? We could upgrade a printer board with I2C (50 printers) but the brainbox who designed the board (HP) left no capabilities to upgrade the firmware. We will have to replace all the boards at great cost to the enviroment. If there is some sort of special clamp you can place over the chip or adapter can some one fill me in?

I have had a goolgle but them seem to be for square multipin devices ours is just 8 pins

Thanks.
 
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A

Andrew Cowan

Senior Member
Is this for raw PICs? If so, it would not be good to put voltage into the inputs/ouptut devices.

Can you give more details of the application?

A
 
premelec

premelec

Senior Member
Please post a picture of the SOIC on the existing board and indicate the pins that are I2C - there are so many configurations and possibilities - there are many probes made and sometimes you can cut a trace and then resolder across it - or - rework with new chip... have you contacted rework folks in your vicinity?
 
hippy

hippy

Ex-Staff (retired)
There are PCB sprung-probe 'needles' used in test jigs which can make contact with a board so you could just sit the board on those with an appropriate jig, and you could possibly bodge something which can be held against the board, and as we'll see below you only need two contact points ( SDA and SCL ) plus a far easier 0V. Maybe just a couple of wires judiciously held and some one else to hit the "go" button ? Look for vias, always useful.

As to doing the programming, it would depend on the circuit and how it was affected by your programmer. If it's legitimate I2C it's an open-collector bus so pulling SDA and SCL to 0V shouldn't be a problem electrically. All you need to do is stop anything else accessing the I2C chip whilst re-programming; may be as simple as grounding reset to the micro it connects to, or simply waiting until the micro has done accessing the I2C. You're probably out of luck if write-protect is hard-wired direct to +V. If SCL is hard-driven you will need to add a pull-up and make sure SCL is floating when accessing I2C.

After that, either bit-bang or use a PICAXE I2C interface to send out the data, as long as the I2C bus is, and used, open collector there should be no risk of damage.
 
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