Infinite resistor

[hakko]

Burn chip uart phisicaly... No better way to protect it!

[desolatordan]

It is a prebuilt PCB that I wrote a calibration for, and because its used in a professional race series the people in charge want to know that the calibration stays constant, so that it cannot be changed by the team using it (within reason), there exists an easy method to change it that everyone knows about so i want to defeat that (again within reason ) whereas it cannot easily be handled in-situ, pretty simple really.

Coat the board in epoxy if you want to stop them from tampering and replacing components.

[charliex]

Well in this instance I want it to be reversible, typically i'd just damage the JTAG.

Epoxy is straightforward to remove, if you use the hard epoxy it risks shrinkage and causing damage. the temperatures are fairly extreme, so especially on the teeny SMD stuff.  It never bonds that well I find. But the reversible thing applies to that too,s o even if I could make it so that it was impossible to remove , it'd be no good.

cheers though.

[Simon]

why not put the board on a box that is soldered shut with some sort of seal on it

[septer012]

Output the ICSP of the controller through a logic design of your choosing. To a header. Coat the whole thing in epoxy, and have an adapter to program it with yourself that you have to plug in.

[charliex]

Space and weight is very limited, once its inside the enclosure there is about 3mm gap.

i like the idea of having a secondary adapter though.

for now though the plan is replace the 0402 metric fuse, i can still access it with a bed of nails. its cheap, cheerful and fast.