Voltage/Current Bricklet 2.0¶

Features¶

• Measure power, voltage and current up to 720W/36V/20A
• 1mW, 1mV, 1mA resolution over the whole range
• Bidirectional current measurement (e.g. charge/discharge)
• Configurable averaging and ADC conversion time

Description¶

The Voltage/Current Bricklet 2.0 can be used to extend Bricks by the possibility to measure power/voltage/current. To do this you only have to put the Bricklet between your power supply (e.g. battery) and your load (e.g. motor).

In case of battery powered systems you can measure the state of the battery by bidirectional current measurement (charge/discharge).

This Bricklet ist not galvanically isolated to the Tinkerforge system. This means that there is a direct electrical connection between the terminals of the Bricklet and the rest of the system. Dependent of the application this can lead to undesired connections, ground loops or short circuits. These problems can be prevented by using the Bricklet together with a Isolator Bricklet.

Technical Specifications¶

Resources¶

• INA226 datasheet (Download)
• Schematic (Download)
• Outline and drilling plan (Download)
• Source code and design files (Download)
• 3D model (View online | Download: STEP, FreeCAD)

Connectivity¶

You have to connect the Voltage/Current Bricklet 2.0 between your power supply and your load. Connect the power supply with the terminal marked with "IN" and the load with the terminal marked "OUT". The polarity is marked with "+" and "-".

The Bricklet measures the voltage between "+" and "-" of the "IN" terminal as well as the current flow from "+" of the "IN" terminal to "+" of the "OUT" terminal.

Test your Voltage/Current Bricklet 2.0¶

To test a Voltage/Current Bricklet 2.0 you need to have Brick Daemon and Brick Viewer installed. Brick Daemon acts as a proxy between the USB interface of the Bricks and the API bindings. Brick Viewer connects to Brick Daemon. It helps to figure out basic information about the connected Bricks and Bricklets and allows to test them.

Connect the Voltage/Current Bricklet 2.0 to a Brick with a Bricklet Cable. Connect a motor and a battery to the Bricklet as displayed in the following picture.

If you connect the Brick to the PC over USB, you should see a new tab named "Voltage/Current Bricklet 2.0" in the Brick Viewer after a moment. Select this tab.

If everything went as expected you can now see the current used by the motor and a graph that shows the current over time.

After this test you can go on with writing your own application. See the Programming Interface section for the API of the Voltage/Current Bricklet 2.0 and examples in different programming languages.

Calibration¶

The current measurement of the Voltage/Current Bricklet is factory calibrated at room temperature. The readings can shift by a few mA if the environment is very cold or very hot. In this case you can recalibrate the Bricklet with a precise multimeter:

Start Brick Viewer and click on "Calibration..." and follow the steps that are described in the GUI.

You can calibrate the voltage as well as the current measurement. In our experience you don't need to calibrate the voltage, it is within 0.5% accuracy without any calibration.

If you remove the factory current calibration a recalibration is necessary because of tolerances in the shunt resistor.

Case¶

A laser-cut case for the Voltage/Current Bricklet 2.0 is available.

The assembly is easiest if you follow the following steps:

• Screw spacers to the Bricklet,
• screw bottom plate to bottom spacers,
• build up side plates,
• plug side plates into bottom plate and
• screw top plate to top spacers.

Below you can see an exploded assembly drawing of the Voltage/Current Bricklet 2.0 case:

Hint: There is a protective film on both sides of the plates, you have to remove it before assembly.

Programming Interface¶

See Programming Interface for a detailed description.