ESC telemetry allows you to monitor the temperature of ESC, and the RPM of the motors. You can also monitor current usage without having a dedicated current sensor on the FC or PDB (real-time current draw and mAh consumed)

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In this guide I will show you how to set up ESC Telemetry in Betaflight to be displayed on OSD.

Limitation of ESC Telemetry

ESC Telemetry is a cool feature, but most people probably find it not that useful. Let me explain why.

ESC Telemetry can report RPM of the motors to the flight controller (how fast the motors are spinning). This information is useful for RPM filter in Betaflight. However bi-directional DShot already does it, and does it better because it’s much faster. RPM reporting from ESC telemetry is just too slow for RPM filter.

Current sensors built into flight controllers and PDB are usually placed right after the XT60 connector, so all current usage can be recorded. ESC telemetry can possibly replace the FC/PDB current sensor, but it’s not the most accurate because they only monitor current usage by the motors. Anything else such as FPV gear, radio receiver etc, are not taken into account.

Betaflight ESC telemetry is also very limited in terms of what you can display in the OSD at the moment (2021).

The featured image on the top of the article, which shows RPM, temperature and current draw of each individual motor, is from my KISS quad running KISS FC and KISS ESC’s. I found this setup to be really useful for analysing the performance of my quad and the motors.

KISS’s ESC Telemetry

On the other hand, in Betaflight, all you can show on the OSD are the temperature of the hottest ESC’s and the averaged RPM of all motors. And really… it’s not that useful to know the temperature of the ESC.

Betaflight’s ESC Telemetry

That’s why I don’t personally normally setup ESC telemetry in my drones. But if you still wanna go ahead and do it, here is how.

Requirement

Hardware and Firmware

• BLHeli32 ESC that has ESC telemetry pad (TX) and flashed with the latest firmware, ESC’s that I have tested this feature on:
  • Betaflight BLHeli32 ESC
  • XRacer Quadrant BLHeli32 ESC
• F3, F4 or F7 Flight Controller running Betaflight 3.1.0 firmware or newer, with 1 spare UART
• Betaflight Configurator (Chrome App) version 1.8.5 or newer

Further reading:

• What is BLHeli32?
• What are the differences in F3, F4 and F7 flight controllers?

How to setup ESC Telemetry in Betaflight OSD

Simply connect all the TX pins (telemetry pads) on the ESC’s to the same RX pin of a spare hardware UART on the flight controller. The FC will be able to read the data from ESC’s one by one.

For 32-bit 4in1 ESC that supports ESC Telemetry, there should be only 1 TX pin. You only need to connect this TX pin to a spare RX pin on the FC.

First of all, open Betaflight Configurator, and in Ports Tab, find the UART that is used for ESC telemetry, under Sensor Input, select “ESC” in the drop-down list. Click “Save” button.

In the Configuration Tab, enable feature “ESC_Sensor“.

You can now use your ESC for voltage and current monitoring in the “Power & Battery” tab by selecting “ESC Sensor”

Important: You also have to set DShot as the ESC protocol (DShot150, DShot300, DShot600 or DShot1200) in order to get ESC Telemetry to work.

Important: If you are not getting any current (amp draw stays 0) when setting the source to ESC sensor, it’s possible that the 4in1 ESC does not support it. For this to work, the 4in1 ESC has to have four shunt resistors (one per ESC). If you can only see one near the power pad, that means it only works with “Onboard ADC” as current meter source, and you need to connect the “Curr” pad on the ESC to the FC.

Further Reading: what is DShot?

You can now display your ESC telemetry data on Betaflight OSD.

Under the OSD tab, you can enable “ESC Temperature” (highest value) and “ESC RPM” (average of all motors).

Further Reading: How to setup and use Betaflight OSD?

To verify if it’s working, simply power on your quad, put on your goggles and arm the quad to see if the RPM number is changing when you move your throttle stick. (Make sure to remove propellers when doing this!)

Make sure to check the accuracy of the voltage and current reading from ESC telemetry, you might need to calibrate them by adjusting the scale values. (default usually should work fine)

Further Reading: How to calibrate current sensor?

That’s it! I will keep this guide updated.