SparkFun Forums

[andyshinn]

Hello,

I am working with the double main board, ESP32 processor, LoRa function board, GPS board, and a larger LiPo battery. I had some questions about this setup.

* I was trying to measure battery voltage via GPIO39 and it only returned the USB voltage when plugged in. It looks like the divider is between the USB voltage instead of the battery voltage. Is there any way to measure the battery voltage instead of the USB voltage?
* I was having trouble getting the LoRa board to work in function slot 1 with GPS in slot 0. This first arrangement was because i need to use UART with the GPS and it only appears the UART is connected when GPS is on slot 0. But then it appears that some of the F# pins the LoRa radio needs are not available on slot 1. Is it possible to use the GPS function board UART along with the LoRa function board on the double main board?
* I am having trouble getting the ESP32 to boot when it is first powered on or I flash a firmware. I have to hit the reset button and then it will boot the program. I was suspecting this was maybe because of a bootstrap pin being help high or low unintentionally. Is there somewhere I am missing that may be unintentionally setting bootstrap pins causing boot issues?

Thanks,

-Andy

[TS-Russell]

It's broken out next to the lipo connector; you should be able to just tap into that (or you could measure the trace directly too, I suppose https://cdn.sparkfun.com/assets/7/3/6/d ... ematic.pdf

You might be able to use the UART multiplexer mentioned ~halfway down in this section of the guide as a workaround https://learn.sparkfun.com/tutorials/mi ... e-overview

Hmmm...not sure about the boot, but maybe measure the j9/j13 (in the schematic) while powering on and see?