Voltage/Current Bricklet¶

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 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).

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 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¶

To test a Voltage/Current Bricklet 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 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" 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. You can see that the voltage drops a bit because of the high load. In this example the motor utilizes about 40W power.

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 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 set "Gain Multiplier" and "Gain Divisor" to 1, press "Save Calibration". Now read the real current measurement from your multimeter and put it in the "Gain Multiplier" field. Put the current current measurement from the Voltage/Current Bricklet in the "Gain Divisor" field and press "Save Calibration" again.

Now the Voltage/Current Bricklet is calibrated for the new environment.

Case¶

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