Installation only by the specialist!

All persons involved in the commissioning,
maintenance and maintenance of the device must:
  • be appropriately qualified
  • have knowledge of the handling of electrical installations
  • Read and understand this manual completely
  • The installation information in this manual is only for qualified persons
    Professional staff
  • Never try to repair the unit yourself! An electric shock can be deadly!
  • Its not allowed to use the board without housing

For more!

For more information, visit:
In addition, the opensource software is constantly being developed further.
The project page can be found on Github:

The SmartPi 2.0 expansion module

SmartPi 2.0 expansion board
Figure 1: SmartPi 2.0 expansion board
Figure 1 shows the SmartPi 2.0 expansion module. The SmartPi 2.0 expansion module enables non­contact current measurement via inductive current sensors with the RaspberryPi. The SmartPi 2.0 expansion module can also be used to measure the voltage and extend the Raspberry Pi to a fully­ fledged SmartMeter.
The SmartPi 2.0 expansion module has 4 inputs for connecting inductive current sensors and 3 inputs for voltage measurement. The system is supplied with the required operating voltage via the L1 voltage connection.
A separate power supply is not required.
A relay for switching, an RS485 connection and an integrated RTC enable the connection of further devices and enable the measuring operation also without an Internet connection.

Anschluss SmartPi 2.0 an den Raspberry Pi

SmartPi connector
Figure 2: SmartPi connector
The SmartPi expansion module is connected via the GPIO port of the Raspberry Pi.
Easiest way to connect is via a 14­pin flat­ribbon cable.
The Raspberry Pi is powered by the SmartPi expansion board.
A power supply for the Raspberry Pi is therefore not required.
Figure 2 shows the names of the connections used.
SmartPi RaspberryPi
(Power off for current)
Relay GPIO18 / PIN12
+5V 5V / PIN2 / PIN4

Setting the current transformers

Jumper settings
Figure 3: Jumper settings

The SmartPi 2.0 is suitable both for the connection of 50mA secondary current transformers (for example SCT013­000), as well as for the connection of current transformers with a secondary current of 1A. Set the secondary current according to your current transformers.

!!! Attention !!!

Too high current can damage the ADC converter of the SmartPi. Therefore, never use a transformer with to high current at the SmartPi. Also make sure that a current transformer is operated with the maximum rated current only.

Assembling of the SmartPi 2.0

Plug the 14­pin flat ribbon cable into the SmartPi's stylus. Please ensure that the cable is pointing towards the battery.

First attach the spacers to the Raspberry Pi.
Hold the spacer bolts from below against the PCB of the Raspberry Pi ...

... and screw the screws from above through the board into the spacer bolts.

The next step is to attach the Raspberry Pi to the SmartPi.

Then plug the ribbon cable onto the connector of the Raspberry Pi.

To mount the SmartPi into the case, please place the front of the case on the electronics ...

... and take the SmartPi into the hand as shown.

Then, place the SmartPi at the top of the case and slide the SmartPi into the subshell.

On the side of the HDMI interface, you may have to slightly push the emblems slightly apart.

Finally, fix the circuit boards with a screw in the case.

Then the upper shell can be placed.

Plug the plugs into the sockets from the outside.
The assembly is finished.

Connection of the current and voltage measurement

Connection diagrams of current and voltage measurement
Figure 4: Connection diagrams of current and voltage measurement
Connecting the SCT013­000
Figure 5: Connecting the SCT013­000

To connect the current measurement, the conductors of the individual phases are routed through the current sensors. The mounting is very simple for folding transformers.
Please note that a possible arrow on the transducers may be the reference direction. The "positive" connection is routed to the respective right pole of the connection terminal. A polarity reversal of the connection leads is not bad, but leads to an incorrect representation of the reference and the incidence.

For the SCT013­000 current sensors (supplied), the red connection cable must be connected to the right (Figure 11). * The measuring voltage is connected to the voltage connections. In this case, care must be taken that the right­hand L1 and the left­hand side of the neutral conductor are N. Be careful not to reverse the connections.

You can also use the SmartPi without voltage measurement.

For this purpose, the software settings can be used to preset a voltage that the SmartPi uses to calculate the power. Note that in this case the power measurement is only possible to a limited extent (no bi­directional measurement, only apparent power, no cos phi, no power factor).

Excursus on current measurement

The SmartPi measures the electrical current in the same way as a current clamp meter in an indirect way. One advantage is that the circuit does not have to be disconnected and the measurement is contactless.
The current I flowing through the conductor generates a magnetic field H which runs in a ring around the conductor (Figure 7).
The current is measured according to the transformer principle with the conductor as the primary winding and the current sensor as the secondary winding.
If a current sensor is now placed around the conductor, the magnetic field of the conductor induces a current in the current clamp that can be measured (Figure 6).
If current flows through two conductors in opposite directions, the resulting magnetic field is cancelled out because the two magnetic fields are directed in opposite directions (Figure 8).
The current sensor can't measure current.

Phase and neutral conductor must not be connected together through one current terminal.
If the consumption of an electrical appliance (e.g. television)  to be measured, the individual conductors in the supply line must be separated. The current clamp has only to be placed around the conductor in which the current flows into the device.
If the current sensor is placed around the entire supply line, the SmartPi cannot measure consumption.


Principle of the current clamp measurement for alternating current
Figure 6: Principle of the current clamp measurement for alternating current (Source: Wikipedia (©CC BY-SA 2.0 de))
Magnetic field around a current-carrying conductor
Figure 7: Magnetic field around a current-carrying conductor
If current flows through two conductors in opposite directions, the total magnetic field is cancelled out.
Figure 8: If current flows through two conductors in opposite directions, the total magnetic field is cancelled out.