Partial ESC telemetry from Tekko32 to Kakute H7

ArduCopter Copter 4.2
1

Hello,

I am in the process of a 7’’ long range quadcopter build, currently in tuning phase, flying well and looking better every TestFlight. However for the ‘long range’ part I would like to know the amps used, so I can evaluate what flight speeds etc are efficient… and there I run into a puzzling problem.

I have bdshot and esc telemetry working, I think, partially.

The quad arms, takes off, flies etc very well so basic motor functionality is working. In mission planner, and in dataflash logs, for each of the four esc’s I can see lots of info, e.g. rpm, raw_rpm, temp, voltage, but no Amps? That is weird, I think, so I am curious if I missed anything obvious.

Some context:

HW setup:
FC: Holybro Kakute H7
ESC: Holybro Tekko32 F4 65A
Motors: T-motor F90 1300kV

FW setup:
FC: Arducopter 4.2.3 (official), platform “Kakute H7 - bdshot”
ESC: BLHeli32 rev 32.9

This is my first post on the forum, and I am not entirely sure if this is a esc/blheli32 issue or a fc/arducopter issue. If I need to include more info pls let me know.

Many thanks!

Boris

2

You can’t get amps from the ESC telemetry usually - you need to use the current signal wire and the battery monitor

3

Hi andyp1per,

Thanks for quick reply!

I guess I’ll wire that up and go from there, think that implies there’ll be only one amp reading for the whole quad instead of one per esc, shame really, amps would be a possible useful indication of motor power used. Which could possibly help in endurance testing, but first see if I get this going…

Have a good weekend!
Boris

4

My understanding is that some high-end ESCs do this, but there are limitations which means it doesn’t work that well.

5

I have an Ori32 4in1 that has one shunt resistor per ESC with the data available thru telemetry.

6

Hi,

I did some more digging, and found that ,as suggested by @andyp1per, the esc telemetry does not carry amps on these esc’s but they use a separate analog wire to do this.

Joshua Bardwell has a video on this (- YouTube ) with a nice explanation. I missed that video obviously… He also mentions that some esc’s (like the Ori32 mentioned by dkemxr and some others) do have 4 current sensors but that is not usually the case anymore.

Anyways, on my setup, the only thing I needed to do is start with the assumption that the amps are carried by a seperate wire and use the Kakute H7 spec sheet and set:

BATT_MONITOR: 4
BATT_VOLT_PIN: 10
BATT_CURRENT_PIN: 11
BATT_VOLT_MULT:11
BATT_AMP_PERVOLT:59.5

Something I did not expect, most of the BATT_* entries do not show up in mission planner until I power the esc board as well (i.e. if the fc is only connected through usb they do not show up).

Just did a TestFlight, I have not bench-tested or verified if the Amp or Volt readings are accurate, but I can see reasonable values now, (averages of 22V/6A in hover) so that’s good.

Guess that closes my question.
Thanks for the help!
Boris

7

I was trying to work out why this did not work out of the box for you because I thought all of those were already set on this board. This reason is that HAL_BATT_MONITOR_DEFAULT is not set by default. It should be and I will do a PR for this. The other settings already have the correct defaults on this board.