Hawk - The Flow Below I²C Level Sensor
Written by Matthew Clark-Massera
Updated at February 24th, 2025
Table of Contents
Please ensure to also read the below for full details on configuring Tasks and I²C Sensors for the Hawk
The Flow Below sensor is an level sensor which can be used for tank monitoring applications. It uses a 60GHz radar to detect the tank level.
Model Number: FB-L-R-I2C-1-1 and FB-L-R-I2C-2-2
3rd Party Sensor
The Level Below Sensor is a 3rd Party sensor - the advice given below is general. Always check the product datasheet direct from the manufacturer. Specific guidance on installation and usage should be obtained directly from the manufacturer. The instructions below are based on a sensor tested at the time of article writing - things may change.
Concurrent use with MB7040
It is important to note that this sensor can not be used concurrently with a MB7040 I²C Ultrasonic Range Sensor (though it is unclear why this would be necessary).
IO Card
Ensure a plug-in IO card with an I²C interface is fitted to the Hawk. Currently the only card with this interface is the AgTech1 card.
Wiring
Flow Below Sensor |
Agtech1 |
Bluetooth+ |
VCC |
Hawk IO 5 |
Hawk IO 7 |
SCL |
Hawk IO 6 |
Hawk IO 5 |
SDA |
Hawk IO 4 |
Hawk IO 6 |
GND |
Hawk GND |
Hawk GND |
Firmware
To read data from the sensor, you will need AgTech1 Card firmware 1.6 or above.
Any Bluetooth+ FW is satisfactory, although we always recommend the latest.
Parameters
I²C Action Parameters
- Select Flow Below as the Sensor Type
- Choose an Analogue to write the values to
- The Sensor Parameter 1 can be used choose the number of samples that are taken by the Hawk before returning a median value. If the parameter is set to zero (default), the Hawk will sample 3 readings; the max number of samples is 10.
The I²C address can be left as a 0.
Task Parameters
Ensure the I²C action you have configured above (Action 1 or 2) is set as an action of the task.
Output/Conversion
With the above parameters, the output would be:
| Value | Analogue | Units | Conversion Example |
| Distance | Analogue Offset Value | mm |
500 = 500mm = 0.5m |
If mounted at the top of a tank, the reported distance would be the distance from the top of the tank to the water - so the water level would be Total Tank Height - Distance.
I²C Config Action
Please note
If running this action, all of the parameters need to be set. e.g. “0” doesn't disable the parameter, it will set the parameter to 0.
The exception to this is the factory reset parameter (parameter 5)
If you have a newer version of the Flow Below Level Sensor (FB-L-R-I2C-2-2 or greater), you are able to write parameters to the sensor using the “I²C Config Action”.
SensorType: This lets you select the sensor you would like to configure. Only FlowBelow for now.
Config params 1 - 6 will be dependent on the sensor. These inputs are UINT32s.
For FlowBelow sensor
- param1 - start distance
- param2 - end distance
- param3 - threshold sensitivity
- param4 - peak sorting
A command to save the parameters will automatically be sent after these config commands
- param5 - factory reset
- if set to 1, ignores all other params and just sends a factory reset command
This action will only be run once (per reset) by the card. So it’s fine to add to a scheduled task (rather than adding it to a disabled task and using an async).
The card/Hawk needs to be reset to run this action again (which would happen when you change these parameters anyway).