3 Replies Latest reply on Dec 14, 2016 4:33 PM by Intel Corporation

    Edison boot behaviour.


      When I recently built a custom board featuring Edison, I discovered that during the boot process the drive strength on UART2_TX changes.


      At first it starts out with a strong drive strength but after passing control to the bootloader (uboot I think) it changed to weak.

      This caused trouble with the level shifters I was using as the "pull up" strength on the RX line to the host (Edison's TX line) was strong enough to trick the level shifter (TXB0108PWR) into thinking the data direction had changed, and form the point on nothing could be received from the UART.


      In the process of debugging this it struck me that I can't really find an authoritative document on the boot process for Edison.

      I think a good low-level description of the boot process would be very helpful for system designers.


      Does anyone know of where I could find such a document?