SPI Failure
embenix opened this issue · comments
Hardware Setup
- Adafruit nrf52840 Feather Express
- Bootloader version: "feather_nrf52840_express_bootloader-0.3.2_s140_6.1.1"
- IDE: VS code with platformio
Problem Description
The SPI communication doesn't work when the board is powered up with battery alone. Otherwise works fine when USB is plugged in. The problem is mainly related to VBUS. When I supply the VBUS with external 5V everything seems to work fine.
To Reproduce
Simply program the board with any SPI example and power up the board with battery or any 3.3v source alone. It won't communicate.
- PINs used: SCK, MOSI, MISO and CS = D10
Expected behavior
In my case, I have connected a fingerprint sensor FPC BM-Lite which is communicating through SPI. The sensor gets initialized well when USB is plugged as shown below:
But throws back communication error when USB is not plugged!!
Data from logic analyzer
When SPI is working fine I can easily see the communication
are you SURE this is the bootloader's bug !!!??? Bootloader don't even enable SPI peripheral at all !!!!
are you SURE this is the bootloader's bug !!!??? Bootloader don't even enable SPI peripheral at all !!!!
I am not 100% sure if this is directly related to bootloader but something wrong is happening in the very beginning. If I power up the board with USB then everything works fine otherwise SPI doesn't work at all.
Maybe try this with a vanilla Arduino SPI program as well, as opposed to platformIO.
I successfully tested the SPI with TFT module from Adafruit and it seems to work fine. So I found a work around. I am initializing SPI TFT first and then initializing the fingerprint sensor. Problem solved. ;)
Thanks for your responses. 👍