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| What is your go to tactic to develop a test jig? |
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| mrburnzie:
Interesting. Are there ready systems which provide testing software with hardware (of course used for complicated systems)? |
| voltsandjolts:
Not enough info on the test requirements to give a meaningful answer of course, but in general the first question I would ask myself is: Why not use a 34970A or such like? It's very flexible device with the card slot architecture. Easily calibrated to traceable standards by your local cal lab (be they keysight or independant, because these are very popular devices). Easy comms with PC for test control software (which may also communicate with other types of devices). Keep custom stuff to a minimum IMO, especially if traceable cal is required. |
| Berni:
It depends a lot on what you are testing. Sometimes the device has all the required connectors and you can just hook it up to a testing cable harness. Sometimes its just a board and you need a bed of nails. We sometimes make these using 3D printing and a PCB to hold the pogo pins. The test system also depends on what you need. Sometimes all you need is a bunch of fixed resistors or voltage sources to provide some input for your device to mesure. Sometimes you can loop outputs back into inputs on the device. Then it is just a matter of the devices own firmware to have a testing mode. Sometimes you need precision test equipment to test it. In that case you might want to have a stack of dedicated equipment on a wheelie cart that can plug into various test jigs for the given product. In that case you would always use a PC to control the test equipment, run the test procedure, record/print results... |
| ajb:
As others have said it depends quite a bit on the project. Sometimes it's possible to take one specimen of the board and convert it into a test fixture, this works especially well when the board has a bunch of specialty IO that is either symmetrical (same number of outputs as inputs) or bidirectional (RS485/CAN/etc). For example I have a small board that is basically a special-purpose Ethernet switch with some additional integrated signaling, and I designed it so that a few jumper cuts/component swaps and new firmware allows it to become its own test system. A simple interposer PCB provides pogo pins for the DUT as usual, connecting all of the required signals including all of the network ports between the DUT and fixture. The main PCB has a footprint for a USB connector that's only fitted on the test fixture board, so with some USB-CDC action on the on-board MCU it's possible to interact with the fixture through a serial terminal, and have it run through automated tests of the various signals in and out of the DUT and read out the switch status to check if all of the DUT's ports can support a link. At some point I'd like to add some external network connectors to the fixture, then it would be possible for the fixture to enable one port between itself and the DUT at a time and do automated per-port throughput testing from a connected PC. Generally if you're building something with an MCU you're going to have a debug serial port, which can be a great start towards automated testing. I have a lib that provides an SCPI-like command system that pretty much goes into every embedded project, so it's super easy to expose internal variables for monitoring or manipulation of a DUT by just adding a new definition to the command list. Something like that, especially if you make the interface consistent across your projects, makes it a lot easier to create test scripts. |
| jmelson:
I make some motion controllers that are all FPGA-based, and controlled through a PC parallel port. So, I made a bed of nails fixture with switches and LEDs to input sense data and display the results. I have a diagnostic program that exercises one feature of the module at a time that runs on a PC. I have tested about 500 of these modules so far. I just test them as sales occur, so I plug in the desired firmware for that order and run the tests. Jon |
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