Thermostat Click Board™

If you need a temperature sensor and relay in one device, you should look no further than the Thermostat Click Board™. It can be used to measure environmental temperature and to directly switch ON/OFF cooling and heating devices, performing all the functions of a thermostat.

The Thermostat Click Board™ carries the MAX7502 IC digital temperature sensor, that also provides an overtemperature alarm/interrupt/shutdown output, and an SN74LVC1G126 single bus buffer from Texas Instruments. MAX7502 IC can measure temperatures from -25°C to +100°C, within the accuracy of ±1.5°C.

The G6D PCB power relay can control up to 5A, 250V AC/30V DC loads.

The click runs on either 3.3V or 5V power supply and communicates with the target MCU over I2C interface.

TEMPERATURE RANGE

The IC can measure temperatures from -25°C to +100°C, within the accuracy of ±1.5°C.

MAX7502 TEMPERATURE SENSOR

MAX7502 temperature sensor measures temperature, converts the data into digital form using a sigma-delta ADC, and communicates the conversion results through an I2C-compatible 2-wire serial interface.

It accepts standard I2C commands to read the data, set the overtemperature alarm trip thresholds, and configure other characteristics.

LOW POWER CONSUMPTION

The MAX7502 temperature sensor typically uses only around 250 µA, and in shutdown mode around 3 µA. With such low power consumption, it is very suitable for home automation devices.

ENABLE/DISABLE THERMOSTAT FUNCTIONALITY

There is also the TE (thermostat enable) pin on the mikroBUS™ pin socket for enabling (high level) or disabling (low) of the thermostat functionality. This is accomplished via the SN74LVC1G126 single bus buffer with 3-state output IC, which serves as an electronic switch between temperature sensor IC output pin and the relay driver circuit.

This way the relay can be permanently disconnected from the sensor IC output. A feature like this can be useful when the sensor IC is only used as an measuring device, or if the thermostat needs to be temporarily disabled.

APPLICATION

HVAC systems, heating systems, cooling systems, simple interrupt ON/OFF temp control, hysteresis controller, etc.

SPECIFICATIONS

PINOUT DIAGRAM

This table shows how the pinout on the Thermostat Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Hardware Reset for MAX7502	RST#	2	RST	INT	15	NC
Thermostat enable	TE	3	CS	TX	14	NC
NC	4	SCK	RX	13	NC
NC	5	MISO	SCL	12	SCL	Serial Data Input/Output Line
NC	6	MOSI	SDA	11	SDA	Serial Data Clock Input
Power supply	+3.3V	7	+3.3V	+5V	10	+5V	Power supply
Ground	GND	8	GND	GND	9	GND	Ground

JUMPERS AND SETTINGS

The table below gives information about the onboard jumpers.

LEDS, BUTTONS AND SWITCHES

The following table gives information about onboard LEDs, buttons and switches.