This issue is most likely related to bootloader and how it initializes. This just happens to cause issue with PSM, because the VDD_5V_PERIPH_EN is pulled up high for short duration. That happens to cause issues on peripheral power.
I have written a short description on cubepilot facebook of this issue. Perma link to the facebook comments.
This happens only on BLUE cubes, NOT on black cubes. Reasons are no yet found. EMI ?!??
This problem has been replicated on multiple units. 5 units so far.
Clear replicable “failure” behavior can be triggered with following procedure.
- Load PSM BQ2431x output close to its maximum allowed current (0.8A or more), but not over current.
- Wait for a short while.
- BQ2431x sets itself to a 220-250mA limiting mode until rebooted. Works like constant current powersupply.
- BQ2431x will regulate voltage to meet 220-250mA limit.
- BQ2431x is not overheating. No hot spots on PSM.
This is definitely hardware failure and only solution for this is to make new revision to cube, carrier board or PSM.
So far custom carrier boards have worked, but will do a bit more testing on those too. Those are using 3DR version of the PSM.
I’m a bit dissapointed as we have had the black cube issue and now we have this issue with BLUE cubes.
TLDR; Cube BLUE is not usable with the default carrier board.
@philip, I would like to hear plan for this.