7Semi MCP9808 Arduino Library

Arduino driver for the Microchip MCP9808 high-accuracy digital temperature sensor.

The MCP9808 provides precise temperature measurement with up to ±0.25°C accuracy, low power consumption, and programmable alert functionality for temperature monitoring applications.

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Features

• High-accuracy temperature measurement (±0.25°C typical)

• Configurable resolution (0.5°C to 0.0625°C)

• Upper, Lower, and Critical temperature thresholds

• Alert output support:

  • Comparator mode
  • Interrupt mode

• Hysteresis configuration

• Shutdown (low power) mode

• Raw temperature access

• Device ID and Manufacturer ID reading

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Connections / Wiring

The MCP9808 uses I²C communication.

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I²C Connection

MCP9808 Pin	MCU Pin	Notes
VCC	3.3V	3.3V only
GND	GND	Common ground
SDA	SDA	I²C data
SCL	SCL	I²C clock
ALERT	GPIO (optional)	Interrupt output

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I²C Notes

• Default I²C address: 0x18
• Address configurable via A0, A1, A2 pins
• Supported bus speeds:
  • 100 kHz
  • 400 kHz (recommended)

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Installation

Arduino Library Manager

1. Open Arduino IDE
2. Go to Library Manager
3. Search for 7Semi MCP9808
4. Click Install

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Manual Installation

1. Download repository as ZIP
2. Arduino IDE → Sketch → Include Library → Add .ZIP Library

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Library Overview

Reading Temperature

float temperature;

sensor.getTemperature(temperature);

• Returns temperature in °C

Reading Raw Temperature

uint16_t raw;

sensor.getTemperatureRaw(raw);

Setting Resolution

sensor.setResolution(MCP9808_RES_0_125C);

Setting Temperature Limits

sensor.setUpperTemperature(30.0);
sensor.setLoweTemperature(20.0);
sensor.setCriticalTemperature(35.0);

Alert Configuration

sensor.setAlertMode(COMPARATOR_OUTPUT);
sensor.setAlertPolarity(ACTIVE_HIGH);
sensor.enableAlert(true);

Reading Alert Status

bool upper, lower, critical;

sensor.getAlert(upper, lower, critical);

Operating Modes

sensor.setMode(SHUTDOWN_MODE);
sensor.setMode(CONTINUOUS_MODE);