mPCIE device/port not powered in battery mode - OPi RK3399

EricP · Published in 2019-7-18 02:31:05

Hi. I'm using an OrangePi RK3399 and if the power supply from the 12V barrel jack is removed, the LTE module connected to the mPCIE port dies. Does anybody know how to make the mPCIE port work while on battery?
The mPCIE dying is due to the port being powered from the main power supply line VBUS from the barrel jack (before the BQ25700a battery charger IC, according to the board's schematics). I don't know why power is not supplied from VSYS like everything else on the board. So, what I've found is that if I want to power the mPCIE port from the battery, the reverse OTG mode from the BQ25700a battery charger IC would need to be set (allowing voltage to flow from the battery to VBUS). The problem is that even if the correct register on the BQ25700a is set, there is a resistor from the OTG Enable pin connected to GND, overriding any software configuration.

Am I missing something or is there no way to mantain the LTE module on the mPCIE port working while powered from batteries?

JacksonMonson · Published in 2021-12-25 18:03:59

Really informative post! As one of the system integrator, I have tried to power on mPCIe device in battery mode and find some strange behavior. Firstly, please check if your board can successfully boot from SD card via UART console which https://www.essaywritinglab.co.uk/buy-essays-online/ site help students to buy essay work. Keep it up!

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