# TFRPM01: Drone RPM tachometer sensor

Find out the current speed of the propellers, engines, landing gears, rotors and other wheels of your drone!

- **Seller:** [ThunderFly](https://lectronz.com/stores/thunderfly), Soběslav, Czechia
- **Price:** €77.70 (EUR, before shipping and taxes)
- **Availability:** In stock
- **Categories:** Robotics, Technology, I2C
- **Certified Open Source Hardware:** [OSHW CZ000009](https://certification.oshwa.org/cz000009.html)
- **Product page:** https://lectronz.com/products/tfrpm01-drone-rpm-tachometer-sensor

## Options

**I2C JST-GH high-flexible silicone cable**

- Without cable
- TFCAB15I2C01: 15 cm I2C cable with JST-GH [Add €2.97]
- TFCAB30I2C01: 30 cm I2C cable with JST-GH [Add €3.47]
- TFCAB45I2C01: 45 cm I2C cable with JST-GH [Add €3.96]

**Probe type**

- Without probe
- Magnetic and optical probe - TFPROBE01A [Add €23.78]
- Hall probe with flange (55100) [Add €23.78]

## Links

- [Documentation](https://docs.thunderfly.cz/avionics/TFRPM01/)
- [Design Files](https://github.com/ThunderFly-aerospace/TFRPM01)

## Images

![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MTYsInB1ciI6ImJsb2JfaWQifX0=--e485a8a6018d44114296d53bfc69a759dbea891c/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2023-05-07T19-3A17-3A33.294Z-EOSR9209-Edit.jpg)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MTcsInB1ciI6ImJsb2JfaWQifX0=--b7c957037d43eda8dec9fd417272319b9eaf0793/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2023-05-07T19-3A17-3A33.294Z-EOSR9196.jpg)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MTgsInB1ciI6ImJsb2JfaWQifX0=--82071d6ee98c50cfbc4f394bb48016235d253864/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2023-05-07T19-3A19-3A02.415Z-EOSR8863.jpg)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MTksInB1ciI6ImJsb2JfaWQifX0=--76e811d5dd894fa13b2fe3d45996d1696014a265/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2023-05-07T19-3A17-3A33.294Z-TFRPM01D_comose.jpg)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MjAsInB1ciI6ImJsb2JfaWQifX0=--b1499fb0c23b6228bbb52d65857e4f368a2b4b6e/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJKUEciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--a1419a086f227676aca33a49760ac51e58b523e3/2021-03-22T21-3A41-3A37.424Z-DSC00624_enhanced.JPG)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MjEsInB1ciI6ImJsb2JfaWQifX0=--2b2b7af4512826cfe9f3481a55a722f5ca981431/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2021-03-22T21-3A41-3A37.424Z-TFRPM01_magnetic_probe.jpg)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MjIsInB1ciI6ImJsb2JfaWQifX0=--cfc90c49385c0bf4787323e6c541aa8f76436d0b/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2021-03-19T12-3A12-3A55.274Z-TFPROBE01A_shipping_content.jpg)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MjMsInB1ciI6ImJsb2JfaWQifX0=--18de86891d91f8bf39f794ee40bec16751e160fc/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2021-03-19T12-3A15-3A19.214Z-TFRPM01B_hall_sensor.jpg)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MjQsInB1ciI6ImJsb2JfaWQifX0=--8cb77f45cf3383bce9c4add49df23b50bfd40611/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJKUEciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--a1419a086f227676aca33a49760ac51e58b523e3/2021-03-22T21-3A41-3A37.424Z-DSC00616_enhanced.JPG)
![TFRPM01: Drone RPM tachometer sensor](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzQ2MjUsInB1ciI6ImJsb2JfaWQifX0=--0cadd8c120b39f2588c2d771c853a3ebd0b6cf58/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJKUEciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--a1419a086f227676aca33a49760ac51e58b523e3/2021-03-22T21-3A41-3A37.424Z-DSC00617_enhanced.JPG)

## Description

# General Description

TFRPM01 is an open-source frequency sensor [tachometer](https://en.wikipedia.org/wiki/Tachometer) intended for the measurement of the speed of rotational actuators on drones. The TFRPM01 sensor itself does not contain a sensing probe. It needs to be connected externally. This allows you to connect many different probes based on different technologies. For basic diagnostics, the sensor is equipped with an LED indicator that shows the logic state of the input pin.

TFRPM01 is supported by Pixhawk autopilots with up-to-date PX4 firmware. For the correct setting of the sensor, see the [official documentation](https://docs.px4.io/master/en/sensor/thunderfly_tachometer.html). The sensor is designed to be able to count high frequencies without overloading the autopilot CPU.

# Technical description

The sensor is based on I²C pulse counter IO [PCF8583](https://www.nxp.com/docs/en/data-sheet/PCF8583.pdf). 

The I2C connector is a 4-pin JST-GH connector compliant with [Pixhawk Reference Standards](https://pixhawk.org/standards/). The second I2C connector can be used as a thought-pass I2C output and allows to connection of another sensor on the same bus. 

There can be up to two TFRPM sensors on one bus. The default sensor address is 0x50 and it can be changed to 0x51 by the use of soldering iron. A sensor with a different address is available on request.

For connecting the probe, the sensor is equipped with a standard three-pin header connector. The connector contains a power and signal pin. The order of pins is GND 5V Signal. It supports 5V TTL signals. The maximum pulse frequency of IO is 20 kHz with a 50% duty cycle. Maximal measured frequency and accuracy depend on the driver setting.


# Supported probes

## Hall-Effect Sensor Probe

Hall-effect sensors (magnetically operated) are ideal for harsh environments, where dirt, dust, and water can contact the sensed rotor.

Many different hall-effect sensors are commercially available. For example, a 5100 Miniature Flange Mounting Proximity Sensor is a good choice. 

![Example of Hall effect probe](https://github.com/ThunderFly-aerospace/TFRPM01/raw/TFRPM01B/doc/img/TFRPM01B_hall_sensor.jpg "Hall effect probe")

## Optical Sensor Probe

The optical sensor can also be used (and maybe is a better fit, depending on the measurement requirements). Both transmissive and reflective sensor types may be used for pulse generation. We suggest the [TFPROBE01](https://docs.thunderfly.cz/avionics/TFRPM01/probe#tfprobe01---omnipolar-magnetic-and-reflective-optical-sensor-probe) reflective optical sensor, which is combined with optional magnetic sensing. 

![Optical Sensor Probe](https://raw.githubusercontent.com/ThunderFly-aerospace/TFPROBE01/TFPROBE01A/doc/img/TFPROBE01A_sensors.jpg "Optical sensor probe")

# PX4 configuration

How to set up the TRRPM01 sensor with [PX4](https://px4.io/) based autopilot is described in [official documentation](https://docs.px4.io/master/en/sensor/thunderfly_tachometer.html). PX4 driver acquires RPM frequency from the sensor and sends it as an internal uORB message. uORB message is logged in autopilot and translated to MAVLink message and can be received/visualized by a ground station (QGroundControl). 

![PlotJugles screen with RPM data](https://raw.githubusercontent.com/ThunderFly-aerospace/TFRPM01/TFRPM01C/doc/img/rpm_graph.png)

The sensor was tested with CUAV V5+ and CUAV Nano autopilot. Other PX4-based autopilots should be also supported with PX4 firmware.

## Use of multiple TFRPM01 sensors

In applications where multiple TFRPM01 are needed, the [TFI2CADT01](https://www.tindie.com/products/26353/) module could be used. That allows the connection of up to six TFRPM01s to a single I2C port.

![Multiple sensors](https://raw.githubusercontent.com/ThunderFly-aerospace/TFI2CADT01/TFICADT01A/doc/img/TFI2CADT01_multi_TFRPM01.jpg)

# The package includes:
- TFRPM01D
- Plastic case

## Optionally
- [I2C silicone cable](https://docs.thunderfly.cz/avionics/TFCAB01/) (TFCABxxI2C01) in lengths of 15cm, 30cm, 40cm
- [Sensing probe](https://docs.thunderfly.cz/avionics/TFRPM01/probe) (TFPROBE01 or Hall probe 55100)

# Accessories

## I2C cables
You may need to purchase additional [I2C cables separately](https://lectronz.com/products/1060). We offer high-quality cables that are compatible with the [Pixhawk standard](https://raw.githubusercontent.com/pixhawk/Pixhawk-Standards/master/DS-009%20Pixhawk%20Connector%20Standard.pdf) and with a [ThunderFly color scheme](https://docs.px4.io/main/en/assembly/cable_wiring.html#i2c-cables) for easy signal type identification. ThunderFly cables are specifically designed with improved resistance to electromagnetic interference and a silicone insulator that makes them highly flexible.

## Sensor probe
The [sensing probe](https://docs.thunderfly.cz/avionics/TFRPM01/probe) is not included in the TFRPM01 sensor package. ThunderFly sells and has tested the following two probes, which can be directly connected to the TFRPM01 sensor board:

  * Hall probe with flange
  * [TFPROBE01 - Omnipolar magnetic and reflective optical probe](https://lectronz.com/products/1065)


# Product changelog
The product is gradually evolving and improving based on user requirements. Currently (as of 05/2023), the TFRPM01D revision is being shipped. In the development process, we keep backward compatibility, for example by keeping the same form factor or communication interface. The complete list of changes is in [releases](https://github.com/ThunderFly-aerospace/TFRPM01/releases).

#### TFRPM01D (from 06/2023)
Roll-back to sticker version with a hole for the screw, to allow user disassembly. 

#### TFRPM01D (from 05/2023)
 * Green case
 * Added an LED indicating the sensor power supply
 * Improved PCB layout

Note: The TFRPM01D sensors shipped from 8. 5. 2023 does not have a hole in the bottom sticker for accessing the screw for disassembling the plastic case. To change the I2C device address or output voltage, it is necessary to remove the bottom sticker and unscrew the screw. (The bottom sticker is a sticker with a QR code)

#### TFRPM01C (from 03/2021) 
 * Gray case
 
#### TFRPM01B (from 12/2020)
 * Orange case

#### TFRPM01A - Was not publicly available