Maxim / Pronto Bricked, blue LED flashing

Our Maxim and Pronto controllers have a regulator that needs an enable-signal from the MCU to stay on, even if the enable-pin on the 39-pin connector is powered. So if the firmware becomes corrupted they won’t be able to stay on long enough to flash new firmware using the SWD pins. This corruption can happen if you flash the wrong firmware file manually or remove power directly after a firmware upload has finished. Usually the blue LED will repeatedly flash then as the enable-pin only powers on the regulator briefly but it never fully boots.

⚠️ Note Firmware prior to 7.00 would sometimes not boot fast enough to enable the regulator, resulting in the device shutting down even with correct firmware. This was mostly a problem on the pronto and got fixed in firmware 7.00. So if you have a blue LED flashing and the controller not booting, start by removing all external loads on the 5V and 12V outputs and see if it boots then. If it does, upgrade the firmware to 7.00 and see if the problem persists. This should be done before trying any of this.

⚠️ Note the Maxim+ has a different regulator and will stay on while the enable-pin is powered, even if it has no firmware. So if the blue LED is flashing on your Maxim+ it is likely to be some different problem.

To fix corrupt firmware, the Maxim and Pronto can be powered from a 12V current-limited (0.5A) power supply through the 12V AUX-output while using an SWD-programmer to upload the correct firmware as shown in this image

⚠️ Do not power the controller from an external supply or battery at the same time!

The correct firmware for your device can be found in the firmware archive

https://github.com/vedderb/vesc_fw_archive

If you have any questions about this procedure please contact us. Also, if you are uncomfortable doing any of this you can send your Pronto or Maxim back to us and we will do it free of charge.