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OpenESC, AM32. Step 1 of 4

Connect your OpenESC and read its firmware

The OpenESC has four small processors, one per motor, each running AM32. Each one has an AM32 bootloader that can receive new firmware. Unlike the flight controller, there is no button to press: the tool wakes the bootloader up through the motor signal wire.

This guide covers connecting and reading, which works today. Installing new AM32 from our firmware page is coming after bench verification; see Install AM32 on your OpenESC.

The usual way in is through the flight controller (called passthrough): the browser talks to the flight controller over USB, and the flight controller passes the data on to the ESC over the 8-pin cable. The flight controller does not have to be an OpenFC: any board running Betaflight can do this. A USB link adapter is an alternative, covered at the end.

Two tools can read the ESCs. The firmware page shows the chip and the firmware name of each ESC. esc-configurator.com also shows the AM32 version and the ESC settings. Both only read when you use them as described here.

You need

  • A computer with Chrome or Edge
  • A USB-C data cable for the flight controller
  • Your OpenESC, connected to a flight controller running Betaflight with the 8-pin cable
  • A charged flight battery

Steps

  1. Take the propellers off. Remove all four propellers. Keep the battery unplugged for now.

    You should see: Bare motor shafts, no battery connected.

  2. Check the flight controller. The ESC must be plugged into the flight controller with the 8-pin cable, and the flight controller must run Betaflight. If you are not sure, follow Check the firmware on your OpenFC first.

    You should see: The flight controller connects in the Betaflight app. Disconnect it there again before the next step: only one page can use the port at a time.

  3. Plug the flight controller into the computer. Connect the flight controller with a USB data cable. Do not press the BOOT button: the flight controller has to run Betaflight normally for passthrough.
  4. Plug in the battery. Now plug the flight battery in, propellers still off. Keep your hands and the cables clear of the motors. The ESC gets its power only from the battery, so it must be in before you read.

    You should see: The motors play their start-up beeps. The ESC is powered.

  5. Read the ESCs. On the firmware page, choose OpenESC and click Read ESC info in its "Check your ESCs" step, then pick the flight controller's port in the list Chrome or Edge shows. That one click connects, switches the flight controller to ESC passthrough and reads every motor output. In esc-configurator instead, click Connect, then Read Settings. Either way, only read: do not flash anything.

    You should see: On the firmware page: one row per motor output Betaflight has set up (four on a quad), each with the chip and the firmware name. In esc-configurator: one entry per ESC with AM32 and its version. Write down what you see.

  6. Disconnect, then unplug the battery. Click Disconnect (on the firmware page or in esc-configurator), then unplug the flight battery.

    You should see: The flight controller is back to normal and connects in the Betaflight app again.

With a USB link adapter instead

If you have no flight controller connected, a USB link adapter for AM32 or BLHeli ESCs can reach the bootloader directly. Wire it to the ESC's signal and ground as the adapter's instructions describe; the OpenESC's pad labels are in its documentation (OpenESC 20×20, OpenESC 30×30). An adapter on one signal line reaches one motor's processor at a time. The battery is still needed to power the ESC.

If it doesn't work

The browser lists no port.
Check the flight controller is running Betaflight (not in bootloader mode), try another data cable, and close the Betaflight app or any other tab that might hold the port.
Every ESC row on the firmware page says "unreadable".
The battery was not plugged in when you clicked Read, so the ESCs had no power. Click Disconnect, plug the battery in (propellers off) and click Read ESC info again. Also check the 8-pin cable is seated at both ends.
The page finds fewer motor outputs than you have motors, or none.
The page reads as many ESCs as Betaflight has motor outputs set up. Check the mixer and motor settings in the Betaflight app, then read again.
The Betaflight app no longer connects after reading the ESCs.
The flight controller is still in ESC passthrough, usually because the tab was closed without Disconnect. Power-cycle the flight controller to leave passthrough: unplug USB and the battery, wait five seconds, then plug USB back in.
One ESC entry is always missing or shows no firmware.
That motor's processor may be waiting in its bootloader after an earlier failed flash. Follow Recover a failed ESC update.
No beeps when the battery goes in.
Unplug the battery at once and check the battery wiring and the connector. If it still stays silent, open a support ticket.

Go to the firmware page