I was hoping someone could clarify what support the nRF52840 has for USB power source detection. Our design uses a 150mAh LiPo battery, with a dedicated PMIC. We have the capability to set the charge current to 100mA, 150mA, or off. From what I've gathered from this Maxim USB charging brief, we can draw 100mAh after we enumerate, and draw up to 1.5A if we confirm the charging device is a dumb charger (data lines shorted together). To be completely compliant, it's necessary to support USB suspend mode, which has a max draw of 2.5mA.Alternatively, a safe non-compliant method would be just to limit the current to 100mA forever, ignoring the suspend mode
Can this state detection be accomplished in software? How about detecting the shorted data lines, indicating a 1.5A USB charger? We don't have the option to add external USB power detection hardware.
Thanks for your time.
Hi, I forwarded this question to the HW designers. I will come back with an answer later.