Entering Bootloader Mode on nRF52 Devices

Every nRF52nRF52A microcontroller chipset made by Nordic, used by several devices such as the RAK Meshtastic Starter Kit and the Lilygo T-Echo. Lower power usage than ESP32. device runs a small program called the bootloader before the firmware starts. In bootloader mode, also called DFUDFU (Device Firmware Update). A state in which a device is placed into for it to receive a firmware update. mode, the device mounts on your computer as a USBUSB (Universal Serial Bus). The wired connection used to power a device, flash firmware onto it, and communicate with it over serial. drive and installs whatever .uf2 file is copied onto it. Drag & Drop, Factory Erase, and Update nRF52 Bootloader all start here. The methods are ordered most convenient first.

Reset button

Most nRF52nRF52A microcontroller chipset made by Nordic, used by several devices such as the RAK Meshtastic Starter Kit and the Lilygo T-Echo. Lower power usage than ESP32. devices enter bootloader mode when you double-press the reset button within about half a second. Press the reset button once to leave it without flashing.

Meshtastic client

Once Meshtastic firmware is installed, the device can be rebooted into bootloader mode from a client without touching a button. Connect the device over USBUSB (Universal Serial Bus). The wired connection used to power a device, flash firmware onto it, and communicate with it over serial. and run:

meshtastic --enter-dfu

The device reboots into bootloader mode and mounts the drive. The Android client's USB File Transfer option does the same over a USBUSB (Universal Serial Bus). The wired connection used to power a device, flash firmware onto it, and communicate with it over serial. connection.

Devices with a single button

The SenseCAP Card Tracker T1000-E and SenseCAP MeshTracker X1 have one button and no reset button, so the double-press doesn't apply. On the Meshtastic OTAFIX bootloader 2.5 or later, connect the USBUSB (Universal Serial Bus). The wired connection used to power a device, flash firmware onto it, and communicate with it over serial. cable, then hold the button while the device starts and keep holding it for 3 seconds. The drive appears a few seconds later. A short press while the device starts, or a hold while the firmware is running, doesn't reach the bootloader. The steps are on each device page: Card Tracker T1000-E and MeshTracker X1.

To leave bootloader mode without flashing, eject the drive. Unplugging doesn't leave bootloader mode: the device stays in it on battery, and plugging it back in only mounts the drive again.

A T1000-E on an OTAFIX bootloader before 2.5 has no button path into the bootloader, and ejecting the drive doesn't leave it, so use the Meshtastic client method and copy a firmware file to get out.

Checking your bootloader version

INFO_UF2.TXT on the mounted drive names the bootloader version, and from OTAFIX 2.4 on carries a Factory-Erase: line. Update nRF52 Bootloader covers moving to a newer one.