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Flashing Guide

warning

Firmware installation is intended for experienced users. An incorrect bootloader, target or connection can leave the ESC unresponsive and may damage the hardware.

info

The board ships with a bootloader and firmware installed. If revision 4 of BOOT4_PA2 is already installed and protected, start at Firmware flashing. Otherwise, follow Bootloader flashing first.

warning

Disconnect power before changing any wiring. Remove the propeller and secure the motor before applying power to the ESC.

Using the Prog Tool? Follow its Quick Start Guide for the built-in SWD and serial interfaces. The procedure below uses separate adapters.

Required hardware

  • PhotonDrive ESC-R-150
  • USB-to-serial adapter and the circuit shown below
  • Power source within the ESC’s rated input range
  • Power leads and connectors appropriate for the installation
  • Signal wire
  • ST-Link V2 programmer only if the bootloader is missing, damaged or outdated

Required software

The ESC-R-150 is an official ESCape32 target named PHOTONDRIVE1. Download that firmware and its matching BOOT4_PA2 bootloader from the Firmware page.

warning

Match the bootloader to the target. BOOT4_PA2 is the only correct bootloader for the ESC-R-150 — its input pin is PA2.

Firmware flashing

  1. With the ESC power disconnected, connect a USB-to-serial adapter to the input signal pin through the diode-transistor circuit:

    • RX to Collector
    • TX to Base through a 1 kΩ resistor
    • Emitter to ESC Input Signal
    • Emitter to TX via a diode
    • GND to ESC GND
    Firmware Flashing Adapter Schematic
    Firmware Flashing Adapter Schematic

  2. Check the wiring, keep the propeller removed, and power the ESC from a protected source within its rated input range.

  3. Flash the PHOTONDRIVE1 firmware using the ESCape32 Tools.

     ./escape32-update -d <serial-port> <path-to-firmware-file>

    On Windows, use serial port format /dev/ttyS# where # is the COM port number minus one (e.g., COM4 → /dev/ttyS3).

    info

    The diode-transistor circuit provides a two-way connection, so no extra flag is required. A one-way connection — such as TX and GND only, or Betaflight passthrough — requires -f to force the update.

    For more information, see the ESCape32 installation guide.

    ESCape32 Tools
    ESCape32 Tools

  4. Confirm communication with the ESCape32 CLI:

    ./escape32-cli -d <serial-port>

    At the CLI prompt, enter info to verify the target and firmware revision. This check does not start the motor.

    ESCape32 Tools CLI
    ESCape32 Tools CLI

Once flashed, the ESC can be configured from the radio over CRSF (see Radio Configuration), over a Wi-Fi Link board, or over the serial CLI.

Disconnect power before changing any wiring.

Bootloader flashing

The bootloader normally needs to be installed only once. Current ESCape32 update tools require revision 4 with bootloader write protection enabled. If BOOT4_PA2-rev4 is already installed and protected, continue at Firmware flashing. If its state is unknown, reinstall it over SWD before updating the firmware.

ESC-R-150 SWD Pinout
ESC-R-150 SWD Pinout

  1. Connect the ST-Link V2 programmer to the ESC’s SWD connector.

    • 3.3 V to 3
    • GND to G
    • RST to R
    • SWDIO to D
    • SWCLK to C
    warning

    The connector has ESD protection, but it is not protected against incorrect wiring. Check every pin before connecting USB power.

  2. Connect the ST-Link V2 programmer to your computer.

  3. Start STM32CubeProgrammer and select the ST-Link V2 by its serial number.

  4. Click Connect and wait for the connection to be established.

  5. Select Full chip erase to erase the ESC’s flash memory. This also removes the installed firmware and saved configuration.

  6. Open Erasing & Programming and select the bootloader binary.

  7. The bootloader is distributed as a .bin file, so set the Start address to 0x08000000.

  8. Click Start programming and wait for the process to finish.

    Bootloader Flashing
    Bootloader Flashing

  9. Open Option bytes, set BOOT_LOCK under Secure Protection, and click Apply.

Once the bootloader is flashed, disconnect the programmer before changing the wiring for the firmware update.

After recovery, continue with Firmware flashing.

Need help with your setup? Contact us.