I just checked our schematic and it looks like ~95% of our circuit can be self-checked using the IMP itself. I can feed many signals back to unused pins, including the forward voltage of the LEDs. Even boost converter functionality can be checked by hardware.voltage. For the test rig, with a bed of needles, I plan to use an IMP001+April. Do you have recommendations?
No, the reference designs like Nora were only very low volume, hence no jigs at all. The imps themselves have jigs, yes, but they’re driven by PCs on the factory floor.
imp001+april is a bit pin limited as you’d need:
- blinkup LED
- “start test” button
- high side power gate control
- i2c to a current monitor (eg http://www.ti.com/product/ina219 )
…and then you have only one line spare, which likely isn’t enough for ISP on the other device.
imp002 might be enough, though it depends on the ISP for the other micro, how much code you’re loading, etc.
What are you wanting the external device to test, exactly?
I want the jest jig (bed of needles) to supply power the Device Under Test (DUT), to measure the current into DUT, to program the wifi settings, to program the other micro on the DUT, and to test parts of the circuit that the DUT cannot self-test. For example we have a battery reverve polarity protection, and a MIC841 that disconnects the the battery when the voltage is <1.7V and re-enables when voltage is >2.15V.
I am sure you have build test jigs to test your reference designs during manufacturing, for example the Nora, and I am interested in the circuits in your test jig.
What is the voltage I should expect on IMP003 VDD_DCDC_IN? Should I measure that voltage or can I verify functionality through something else?
I believe it’s 1.5v, but if this isn’t up the wifi won’t be working so you won’t get very far
Looks like the board need only 8 test points for programming another micro and to test circuits that can not be self tested by de IMP under test