I’m trying to build a custom power module with a USB socket for deploying and D socket to power my boards. From the schematics (SP, DP and AA module) i see that there is a signal UD_Vbus connected to socket D. In SP and AA modules it is connected to pin 3, in DP module it is connected to pin 6. This signal seems to be a part of the USB 5V (it is connected to a voltage divider).
From the schematics of cerberus board, i see that pin 3 is connected to PA9 of the processor (pin 42) and pin 6 is connected to PB12 (pin 33). But for G120HDR board, pin 3 and pin 6 are not connected.
So, my questions are:
- Do i need to connect UD_VBUS to pin 3 (or pin 6) of the D socket?
- What is the purpose of that signal?
- My custom module is going to be powered by batteries, LM1117 is a good/efficient LDO to generate 3,3V?