This is a demo project for the Pmod ISNS20 and the Pmod SSR, both made by Digilent. The Pmod ISNS20 is used to measure the current through a DC motor. As the current sensor has to be calibrated (the offset most be measured), the solid state relay is used to disconnect the load while making this measurement, then connect it back.
With the help of this solid state relay, one can easily switch on/off relatively high loads (it blocks up to 48V and switches up to 6A). The device is controlled by sending 1-bit binary data to its ON pin (1-on, 0-off).
The current sensor can measure from -20A to +20A and communicates using SPI interface. Due to the large range of the sensor, inaccuracies may appear when measuring small currents (in the mA range).
To control the Pmods, an Arduino UNO is used, which also sends the data to the computer. The 6V DC motor is used as a load in this project, as it's consumption is high enough to be measured by the Pmod ISNS20.