Enjoy the warmth you desire with TMP392 and PIC18F57Q43

Thermostat 4 Click is based on the TMP392, a resistor-programmable temperature switch from Texas Instruments that enable protection and detection of system thermal events from 30°C to 130°C. The device powers on when the supply voltage goes beyond 1.5V, and starts sampling the input resistance to set the two trip points and hysteresis value after power-on. Trip point for channel A can be set manually using onboard trimmer while trip point for channel B is set using TPL0501 digital potentiometer with 256 wiper positions used as as a two-terminal rheostat. With end-to-end resistance of 100 kΩ internal registers of the TPL0501 can be accessed using a SPI interface. The position of the wiper (W) terminal is controlled by the value in the 8-bit Wiper Resistance (WR) register. When the WR register contains all zeroes (zero-scale), the wiper terminal is closest to its L terminal. As the value of the WR register increases from all zeroes to all ones

(full-scale), the wiper moves from the position closest to the L terminal, to the position closest to the H terminal. At the same time, the resistance between W and L increases, whereas the resistance between W and H decreases. The relay is activated by the host MCU. The voltage for the coil activation is 5V, while the current through the coil is 40mA. The MCU is not able to drive the coil directly, therefore an N-chanel FET had to be added. Its gate is controlled by the host MCU, allowing the coil to drain enough current from the 5V mikroBUS™ power rail. A red color LED, labeled as ACTIVE is used to indicate that the transistor is in an open state and that the current is running through the relay coil. When the current through a coil (or any other inductor) is suddenly changed, the backEMF will be generated, opposing the changes of the current. This can sometimes lead to damage to the control circuit: in this case, the transistor will become inversely polarized. To

prevent this from happening, a flyback diode is added across the coil. During the normal operation, this diode does not conduct any current. However, when the coil is switched OFF, the inverse polarization will cause the current to pass through this diode with minimum resistance. This prevents inverse (flyback) voltage from building up, so the transistor remains safe. The Click board™ is equipped with all the necessary elements, required to provide a reliable operation: it has a varistor across the relay output contacts, preventing excessive voltage transients, it has a flyback diode for the backEMF generated within the relay coil, and a durable mechanical relay, that can withstand up to 20,000,000 mechanical cycles (no load connected). These features allow Thermostat 4 click to be used for a wide range of applications that have to be thermally controlled: various home appliances, air conditioners, cooling fans, small heaters, and more.

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.