Recovering bootloader and flashing RNode firmware to Heltec T114 to replace meshtastic

[easytarget]

Not so much a question; I was going to ask for help here but found my solution and figured I should share it in classic 'tl;dr' fashion.

I could not get the RNode firmware (any version, mainline or CE) to flash properly on my Heltec T114 (v2).

• This device has had the latest meshtastic firmware on it since I got it.

Using the Online tool (https://liamcottle.github.io/rnode-flasher/) I could put my device in DFU mode and upload the firmware files with the progress being shown, and get the 'uploaded OK' dialog afterwards. But after that provisioning failed, and the device has no display or USB serial response. I repeated this several times with both mainline and CE firmware.

I resolved It by using the 'Factory erase' firmware also provided by meshtastic. This resets the board partitioning back to a 'vanilla' state, and is super easy to use, just download and drag the nrf_erase2.uf2 file onto the device while in DFU mode).

• I believe the partitioning scheme used in the meshtastic firmware is the issue;

Having done this I was immediately able to re-run the rnode online flasher, go back into DFU mode, and this time after the upload completed the device rebooted with the RNode software running (display came on, provisioning worked).

I figured this is worth documenting / sharing here.

Meshtastic use this to solve uploading issues, but it also worked for me to allow the Rnode firmware. It's not very obvious what is happening (I had a brief 'oh no, is it bricked? moment after the first failed flash).

[markqvist]

Thanks a lot for sharing this guide! I wonder if Meshtastic changed the partition mapping to something weird, since this definitely used to work. Or maybe, it's simply that the web flasher doesn't handle the partition mapping fully, if it already has a different one. As far as I know, if you flash it with rnodeconf, it will work regardless of what partition map is on the device to begin with.

[easytarget]

if you flash it with rnodeconf, it will work

Which is what I should have tried, of course ;-)

It's good to be aware of the 'erase' flash target. I have used it several times recently in an (abortive) attempt to get micropython running on my V1 T114. (The V1 being the version with LoRa tx defects and BT issues, I have a V2 replacement, but they never asked me to return the V1..)

[cobraPA]

Their erase bootloader just seems to format the eeprom…. The bootloaders are in the meshtastic git (some older ones are in Mark Birss’s git),so if we need to we can look at them and figure out what is going on. It’s odd, the setup of the whole nrf52 bootloader and meshtastic seems to have some strange dependency.