First boot issue
I have recently received a parcel containing a Spresense kit (main board, extension board and camera module) but unfortunately have been unsuccessful in getting it up and running. I was following the tutorials on your website to connect it with my setup (Ubuntu 18.04 64-bit + Arduino IDE 1.8.16).
If I plug a USB cable to the main board's micro-USB connector, the power LED does not light up although the serial interface ttyUSB0 appears (dmesg | grep "cp21.*attached" even returns usb 1-1: cp210x converter now attached to ttyUSB0). Alternatively, connecting to the expansion board's micro-USB connector lights up the main board's power LED, but the serial interface does not show up.
I've tried nonetheless to burn the bootloader via the Arduino IDE or returning to factory default settings via your recovery tool but neither have solved the issue.
Do you have any insights with regards to this? BTW I tried with different USB ports / USB cables / computers.
Thanks for your help!
From your description it looks like the LDO (5V-> 4V) of IC5 is broken. According to the specification, the maximum voltage for this LDO is 6V.
It's possible that the USB power supply has exceeded 6V and the LDO has been damaged. Maybe you used an adapter or battery that doesn't properly comply with the USB-PD standard.
In the Spresense documentation you can find:
"Powering the Spresense board using a conversion adapter for USB Type-C AC adapter etc. to microB may result in a voltage exceeding the VBUS withstand voltage, which may destroy the Spresense board. (Conversion adapters with Type-C receptacle connectors are non-USB standard compliant)."
Additionally, please see block diagram: