PyCubed V5 Hardware Debugging

[polygnomial]

Hey! I am debugging 5 PyCubed v05s that were SMT assembled. The boards don't have 3.3V regulators or radios yet, and are also missing L3, and a the usual DNP components.

I've been powering them with a bench power supply, and they seem to only work when I have the debugging header connected to my computer in addition to the USB.

I will update here as I debug! I am planning to first solder on a 3.3V regulator, and will go from there :-).

Running Beepsat (Simple) on each board:

[maholli]

Hey @polygnomial!

Ok so you have partially-assembled boards. Since they don't have 3V3 regulators, you're supplying 3V3 from an external power supply so you can program the micros and test things.

Few things jump out at me:

• USB charger and power monitor (both are I2C devices) are powered by the VIN before it reaches the 3V3 regulator. If you're only piping in 3V3 directly, these wont get powered. This is also likely effecting the IMU.
• Not directly relevant in your case, but when powering from an external power supply and also connecting to the board via USB, you need to be careful with ground loops. Is your supply floating relative to your USB connection? If USB is a laptop, is laptop plugged into power supply? That kind of stuff.
• Your REPL print outs look strange - I noticed you have baudrate set to 9600. Bump that up to 115200 (and enable ASCII color codes, if possible) and that should clean itself up.

[polygnomial]

Thanks for the suggestions! I switched back to screen for ASCII color. I soldered on a 3V3 regulator, and here are the results. The BMX160 is not populated either, so it makes sense that it doesn't work. I will add a radio and see if I can get that working too.

[maholli]

Ah! Then everything appears to be working. 👍

[polygnomial]

Yep!

[Mikefly123]

Just to tack onto this thread, here was the final BOM as installed by PCBWay:
quotation-T-1D8W104511F-W104511FS1D7-10sets-PyCubed V5 BOM 2021-9-9.xlsx