Result: --id 255 isn't supported by my voxl-esc-tools (bin version 1.9) — it scans, finds IDs 0–3, then exits with ERROR: Specified ESC ID not found. Running ./voxl-esc-spin.py --id 2 --power 0 works and I do see BOARD_VOLTAGE and BOARD_CURRENT printed. So the ESC is emitting the battery telemetry message correctly.

But PX4 still never publishes battery_status:

VOXL2 M0054, voxl-suite 1.6.3, 4× M0138-1 ESCs on firmware 39, tools 1.9
BAT1_SOURCE = ESCs, VOXL_ESC_PUB_BST enabled in QGC
POWER_MANAGER=none in /etc/modalai/voxl-px4.conf (was voxlpm; changed per the comment "use none for modalai mini-esc since the esc driver handles PM" — I have no voxlpm module, the ESC is my only sensing)
px4-listener battery_status 5 → "never published", after systemctl restart voxl-px4 and a full reboot
esc_status is healthy: 4 ESCs online, esc_voltage 24.055 (6S)

Questions:

• How do I verify VOXL_ESC_PUB_BST on the flight side? px4-qshell param show VOXL_ESC_PUB_BST doesn't return anything readable in my terminal, so I can't confirm the QGC write reached the DSP.

• Does the voxl-esc driver poll ESC channel 2 for telemetry in my configuration? If its telemetry rotation depends on the motor mapping, could it be missing the one channel that sends the battery message?

• Is POWER_MANAGER=none correct for the FPV 4-in-1 (M0138), or is that comment specific to the mini ESC (M0129)?

ID         : 1
Board      : version 42: ModalAi 4-in-1 ESC (M0138-1)
UID        : 0x203837304848570400490045
Firmware   : version   39, hash a58f5f6f
Bootloader : version  187, hash aad89d63

ID         : 2
Board      : version 42: ModalAi 4-in-1 ESC (M0138-1)
UID        : 0x20383730484857040029004D
Firmware   : version   39, hash a58f5f6f
Bootloader : version  187, hash aad89d63

ID         : 3
Board      : version 42: ModalAi 4-in-1 ESC (M0138-1)
UID        : 0x20383730484857040029004E
Firmware   : version   39, hash a58f5f6f
Bootloader : version  187, hash aad89d63

WARNING:
This test requires motors to spin at high speeds with
propellers attached. Please ensure that appropriate
protective equipment is being worn at all times and
that the motor and propeller are adequately isolated
from all persons.

For best results, please perform this test at the
nominal voltage for the battery used.

Type "Yes" to continue: yes
[0.017] (2) RPM: 0, PWR: 0, VOLTAGE: 23.842V, TEMPERATURE: 37.47C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.842V, BOARD_CURRENT: -0.096A
[0.035] (2) RPM: 0, PWR: 0, VOLTAGE: 23.839V, TEMPERATURE: 37.47C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.839V, BOARD_CURRENT: -0.072A
[0.054] (2) RPM: 0, PWR: 0, VOLTAGE: 23.843V, TEMPERATURE: 37.48C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.843V, BOARD_CURRENT: -0.080A
[0.076] (2) RPM: 0, PWR: 0, VOLTAGE: 23.839V, TEMPERATURE: 37.49C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.839V, BOARD_CURRENT: -0.040A
[0.092] (2) RPM: 0, PWR: 0, VOLTAGE: 23.844V, TEMPERATURE: 37.47C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.844V, BOARD_CURRENT: -0.096A
[0.121] (2) RPM: 0, PWR: 0, VOLTAGE: 23.843V, TEMPERATURE: 37.46C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.843V, BOARD_CURRENT: -0.064A
[0.133] (2) RPM: 0, PWR: 0, VOLTAGE: 23.843V, TEMPERATURE: 37.44C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.843V, BOARD_CURRENT: -0.008A
[0.153] (2) RPM: 0, PWR: 0, VOLTAGE: 23.840V, TEMPERATURE: 37.46C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.840V, BOARD_CURRENT: -0.048A
[0.178] (2) RPM: 0, PWR: 0, VOLTAGE: 23.841V, TEMPERATURE: 37.45C, CURRENT: 0.000A, BOARD_VOLTAGE: 23.841V, BOARD_CURRENT: -0.064A

Here is some background..

The Mini ESC (M0129) and the FPV ESC (M0138) do not have individual channel current sensing (unlike M0134 ESC), so the individual ESC channel current is reported as 0, while each ESC channel still reports the measured voltage in the standard telemetry packet sent to the FC. For these two ESCs (M0129 and M0138), one of the ESC channels measures the total board current that flows through the ESC and sends out a second telemetry message with just voltage and total current. For M0129, the ESC channel 3 does this, and for M0138, channel 2 (0-indexed).

The telemetry messages are sent from the ESC to the FC (VOXL2) via UART and is parsed in the PX4 in voxl-esc driver. In the voxl-esc driver, if the battery status telemetry message is received from the ESC and VOXL_ESC_PUB_BST is enabled, then the driver will publish the battery_status topic with the battery voltage and current from the ESC telemetry message.

In order to do a quick test to make sure the ESC is sending out the battery status, you can do the following:

• stop px4 : systemctl stop voxl-px4
• test the ESC using voxl-esc tools (note that these tools are not part of px4):

cd /usr/share/modalai/voxl-esc-tools
./voxl-esc-spin.py --id 255 --power 0

Note that you will be running a spin test command (take off props for safety!), but the command is 0, so the motors will not spin, but you will see the telemetry from the ESC being printed in the terminal on voxl2. You will seeBOARD_VOLTAGE and BOARD_CURRENT being reported and that is coming from the extra telemetry message from the ESC. If you see this current printed, then the ESC is sending the correct information.

The argument --id 255 will tell the test script to communicate with all 4 ESC channels and the commands will be sent and telemetry requested from all 4 ESC channels (including the channel that sends back the battery status telemetry message).

Can you please check this?

voxl2:/usr/share/modalai/voxl-esc-tools$ ./voxl-esc-spin.py --id 255 --power 0
Detected Python version : 3.6.9 (default, Mar 10 2023, 16:46:00) 
[GCC 8.4.0]
Found voxl-esc tools bin version: 1.9
VOXL Platform: M0054
Detected RB5 Flight, VOXL2 M0054 or M0104!
INFO: Scanning for ESC firmware: /dev/slpi-uart-2, baud: 2000000
Sending library name request: libslpi_qrb5165_io.so
Sending initialization request
INFO: ESC(s) detected on port: /dev/slpi-uart-2, baud rate: 2000000
	ID         : 0
	Board      : version 40: ModalAi 4-in-1 ESC (M0129-3)
	UID        : 0x2039333557555313000F0036
	Firmware   : version   39, hash 9c6233d6
	Bootloader : version  184, hash 10bf24c8

	ID         : 1
	Board      : version 40: ModalAi 4-in-1 ESC (M0129-3)
	UID        : 0x2039333557555313000F0032
	Firmware   : version   39, hash 9c6233d6
	Bootloader : version  184, hash 10bf24c8

	ID         : 2
	Board      : version 40: ModalAi 4-in-1 ESC (M0129-3)
	UID        : 0x2039333557555313000F0034
	Firmware   : version   39, hash 9c6233d6
	Bootloader : version  184, hash 10bf24c8

	ID         : 3
	Board      : version 40: ModalAi 4-in-1 ESC (M0129-3)
	UID        : 0x2039333557555313000F0038
	Firmware   : version   39, hash 9c6233d6
	Bootloader : version  184, hash 10bf24c8

---------------------

WARNING: 
This test requires motors to spin at high speeds with
propellers attached. Please ensure that appropriate
protective equipment is being worn at all times and
that the motor and propeller are adequately isolated
from all persons.

For best results, please perform this test at the
nominal voltage for the battery used.

Type "Yes" to continue: yes
[0.015] (0) RPM: 0, PWR: 0, VOLTAGE: 0.000V, TEMPERATURE: 0.00C, CURRENT: 0.000A
[0.015] (1) RPM: 0, PWR: 0, VOLTAGE: 16.049V, TEMPERATURE: 38.24C, CURRENT: 0.000A
[0.015] (2) RPM: 0, PWR: 0, VOLTAGE: 0.000V, TEMPERATURE: 0.00C, CURRENT: 0.000A
[0.015] (3) RPM: 0, PWR: 0, VOLTAGE: 0.000V, TEMPERATURE: 0.00C, CURRENT: 0.000A
[0.036] (0) RPM: 0, PWR: 0, VOLTAGE: 0.000V, TEMPERATURE: 0.00C, CURRENT: 0.000A
[0.036] (1) RPM: 0, PWR: 0, VOLTAGE: 16.049V, TEMPERATURE: 38.24C, CURRENT: 0.000A
[0.036] (2) RPM: 0, PWR: 0, VOLTAGE: 16.059V, TEMPERATURE: 38.85C, CURRENT: 0.000A
[0.036] (3) RPM: 0, PWR: 0, VOLTAGE: 0.000V, TEMPERATURE: 0.00C, CURRENT: 0.000A
[0.059] (0) RPM: 0, PWR: 0, VOLTAGE: 16.039V, TEMPERATURE: 38.22C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.047V, BOARD_CURRENT: 0.240A
[0.059] (1) RPM: 0, PWR: 0, VOLTAGE: 16.049V, TEMPERATURE: 38.24C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.047V, BOARD_CURRENT: 0.240A
[0.059] (2) RPM: 0, PWR: 0, VOLTAGE: 16.059V, TEMPERATURE: 38.85C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.047V, BOARD_CURRENT: 0.240A
[0.059] (3) RPM: 0, PWR: 0, VOLTAGE: 16.047V, TEMPERATURE: 38.86C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.047V, BOARD_CURRENT: 0.240A
[0.075] (0) RPM: 0, PWR: 0, VOLTAGE: 16.039V, TEMPERATURE: 38.22C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.047V, BOARD_CURRENT: 0.240A
[0.075] (1) RPM: 0, PWR: 0, VOLTAGE: 16.049V, TEMPERATURE: 38.23C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.047V, BOARD_CURRENT: 0.240A
[0.075] (2) RPM: 0, PWR: 0, VOLTAGE: 16.065V, TEMPERATURE: 38.89C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.047V, BOARD_CURRENT: 0.240A
[0.075] (3) RPM: 0, PWR: 0, VOLTAGE: 16.047V, TEMPERATURE: 38.86C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.047V, BOARD_CURRENT: 0.240A
[0.101] (0) RPM: 0, PWR: 0, VOLTAGE: 16.044V, TEMPERATURE: 38.19C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.041V, BOARD_CURRENT: 0.232A
[0.101] (1) RPM: 0, PWR: 0, VOLTAGE: 16.049V, TEMPERATURE: 38.23C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.041V, BOARD_CURRENT: 0.232A
[0.101] (2) RPM: 0, PWR: 0, VOLTAGE: 16.065V, TEMPERATURE: 38.89C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.041V, BOARD_CURRENT: 0.232A
[0.101] (3) RPM: 0, PWR: 0, VOLTAGE: 16.041V, TEMPERATURE: 38.91C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.041V, BOARD_CURRENT: 0.232A
[0.119] (0) RPM: 0, PWR: 0, VOLTAGE: 16.044V, TEMPERATURE: 38.19C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.041V, BOARD_CURRENT: 0.232A
[0.119] (1) RPM: 0, PWR: 0, VOLTAGE: 16.054V, TEMPERATURE: 38.23C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.041V, BOARD_CURRENT: 0.232A
[0.119] (2) RPM: 0, PWR: 0, VOLTAGE: 16.060V, TEMPERATURE: 38.88C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.041V, BOARD_CURRENT: 0.232A
[0.119] (3) RPM: 0, PWR: 0, VOLTAGE: 16.041V, TEMPERATURE: 38.91C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.041V, BOARD_CURRENT: 0.232A
[0.137] (0) RPM: 0, PWR: 0, VOLTAGE: 16.044V, TEMPERATURE: 38.25C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.043V, BOARD_CURRENT: 0.248A
[0.137] (1) RPM: 0, PWR: 0, VOLTAGE: 16.049V, TEMPERATURE: 38.22C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.043V, BOARD_CURRENT: 0.248A
[0.137] (2) RPM: 0, PWR: 0, VOLTAGE: 16.060V, TEMPERATURE: 38.88C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.043V, BOARD_CURRENT: 0.248A
[0.137] (3) RPM: 0, PWR: 0, VOLTAGE: 16.043V, TEMPERATURE: 38.90C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.043V, BOARD_CURRENT: 0.248A
[0.156] (0) RPM: 0, PWR: 0, VOLTAGE: 16.044V, TEMPERATURE: 38.25C, CURRENT: 0.000A, BOARD_VOLTAGE: 16.043V, BOARD_CURRENT: 0.248A