Hall Switch 2 Click Board™

Product Code: MIKROE-4788

How Does The Hall Switch 2 Click Board™ Work? The Hall Switch 2 Click Board™ as its foundation uses the MHA100KN, a high-performance, low-power Hall-Effect sensor from MEMSIC. This Click board™ detects the presence and magnitude of a magnetic field using the Hall effect. It consists of two high-quality relays, which the MHA100KN activates. When the north pole magnetic field is introduced to the sensor, one of the relays will be activated; otherwise, the other relay will be activated. The outputs of the MHA100KN are routed to the LM358 operational amplifier, which works as the inverting comparators. When the output of the MHA100KN is activated, pulled to a low logic level, the output from the comparator will be set to 5V, which will cause biasing of the BJTs, allowing current flow through the relay coil and thus forming a magnetic field necessary for closing the relay contacts. A Schottky diode across the relay coils prevents the reverse kickback voltage, which forms due to the inert nature of the coils.

Hall Switch 2 Click communicates with MCU using two GPIO pins labelled S and N. The north pole output is routed to the CS pin, while the south pole output is routed to the INT pin of the mikroBUS™ socket so that the MCU can monitor the status of the MHA100KN. Activation of the relay coils is also visually indicated by the yellow and red LEDs, respectively. Two varistors VR1 and VR2, are used to prevent voltage peaks when the load is connected or disconnected on the relay output contacts. However, the relays allow up to 5A for 250VAC / 30VDC, so the connected load should not exceed these power ratings. This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it allows both 3.3V and 5V capable MCUs to use the communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development. Specifications Type Magnetic Applications Can be used for various applications activated by the magnetic field, such as contactless switches, lids or tray position detecting switches, or other similar applications that require contactless switching of the relay contacts On-board modules MHA100KN - high-performance, low-power Hall-Effect sensor from MEMSIC Key Features Low power consumption, reliable contactless switching by the magnetic field, separate sensors for both south and north pole magnetic fields, high-quality compact relays, and more Interface GPIO Compatibility mikroBUS Click board size L (57.15 x 25.4 mm) Input Voltage 3.3V or 5V Pinout diagram This table shows how the pinout on Hall Switch 2 Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns). Notes Pin Pin Notes NC 1 AN PWM 16 NC NC 2 RST INT 15 S South Pole North Pole N 3 CS RX 14 NC NC 4 SCK TX 13 NC NC 5 MISO SCL 12 NC NC 6 MOSI SDA 11 NC Power Supply 3.3V 7 3.3V 5V 10 5V Power Supply Ground GND 8 GND GND 9 GND Ground Onboard settings and indicators Label Name Default Description LD1 PWR - Power LED Indicator LD2 S - Magnet South Pole LED Indicator LD3 N - Magnet North Pole LED Indicator JP1 VCC SEL Left Logic Level Voltage Selection 3V3/5V: Left position 3V3, Right position 5V Hall Switch 2 Click electrical specifications Description Min