MCP9808 precision I2C temperature sensor

This is a module that makes it easy to connect to a MCP9808 Precision I2C Temperature sensor.

The MCP9808 is a precision I2C temperature sensor from Microchip between -20°C and +100°C with +- 0.25°C / +- 0.5°C (typical/maximum) accuracy. This module makes it easy to connect this sensor with an espruino board.

Use the MCP9808 module for it.

Wiring Up

Software

How to use the module:

I2C1.setup({scl:B6,sda:B7, bitrate: 60000});
var mcp = require("MCP9808").connect(I2C1, 0b000); // 0b000 means A2 = A2 = A1 = GND 
var temperature = mcp.getTemperature();
console.log("Temperature: " + temperature + " C");

The sensor can handle bitrates up to 400000 but I had stability problems with this.

Reference

/* returns the current sensor resolution as enum
 *     MCP9808.RESOLUTION_0_5_CELSIUS   0.5°C,    approx.  30 ms
 *     MCP9808.RESOLUTION_0_25_CELSIUS  0.25°C,   approx.  65 ms
 *     RESOLUTION_0_125_CELSIUS         0.125°C,  approx. 130 ms
 *     RESOLUTION_0_0625_CELSIUS        0.0615°C  approx. 250 ms
 */
MCP9808.prototype.getResolution = function () { ... }

/* set the current sensor resolution
 * Allowed values are:
 *     MCP9808.RESOLUTION_0_5_CELSIUS   0.5°C,    approx.  30 ms
 *     MCP9808.RESOLUTION_0_25_CELSIUS  0.25°C,   approx.  65 ms
 *     RESOLUTION_0_125_CELSIUS         0.125°C,  approx. 130 ms
 *     RESOLUTION_0_0625_CELSIUS        0.0615°C  approx. 250 ms
 */
MCP9808.prototype.setResolution = function (resolution) { ... }

/* return the temperature in °C
 */
MCP9808.prototype.getTemperature = function () { ... }

/* return whether the sensor is running or in power down mode
 * true if the sensor is running
 */
MCP9808.prototype.isRunning = function () { ... }

/* wakeup the sensor from power down mode
 */
MCP9808.prototype.wakeup = function () { ... }

/* Set the sensor in power down mode
 * The temperature can be read but will not be updated anymore.
 */
MCP9808.prototype.shutdown = function () { ... }

/* returns whether a configured limit temperature (lower, upper, critical) is reached
 * {
 *     aboveCriticalLimit: true/false,
 *     aboveUpperLimit: true/false,
 *     belowLowerLimit: true7false
 * }
 */
MCP9808.prototype.getAlertStatus = function () { ... }

/* get the hysteresis for alerts in °C
 * If an alert has triggered and alert mode is CHECK_ALL_LIMITS_COMPARATOR or CHECK_CRITICAL_LIMIT
 * the current temperature must below the limit temperature minus hysteresis.
 * This avoids the flickering of the ALERT pin when temperature is around a configured limit temperature.
 *
 * Only 4 different values are supported. Possible return values would be
 *   0.0°C, 1.5°C, 3.0°C or 6.0°C.
 *
 */
MCP9808.prototype.getHysteresis = function () { ... }

/* set the hysteresis for alerts in °C
 * Only 4 different values are supported: 0.0°C, 1.5°C, 3.0°C or 6.0°C.
 */
MCP9808.prototype.setHysteresis = function (celsius) { ... }

/* returns whether the ALERT pin goes high or low when an temperature alert occurs.
 * returns true is the ALERT pin goes high when an temperature alert occurs.

 * Hint: The ALERT pin is an open-drain-output. At least a pull-up resistor is required!
 */
MCP9808.prototype.isAlertHighActive = function () { ... }

/* set the output polarity of the ALERT pin
 *   true - the ALERT pin goes high when ALERT occurs
 *   false - the ALERT pin goes low when ALERT occurs
 *
 * Hint: The ALERT pin is an open-drain-output. At least a pull-up resistor is required!
 */
MCP9808.prototype.setAlertHighActive = function (highActive) { ... }

/* If the sensor is in alert mode MCP9808.CHECK_ALL_LIMITS_INTERRUPT then the alert will not
 * disapper when the temperature is in a valid range again.
 * Only a call the clearInterrupt() will reset the alert.
 */
MCP9808.prototype.clearInterrupt = function () { ... }

/* get the configured alert mode. Possible return values are
 *   MCP9808.DISABLED
 *   MCP9808.CHECK_ALL_LIMITS_COMPARATOR
 *   MCP9808.CHECK_ALL_LIMITS_INTERRUPT
 *   MCP9808.CHECK_CRITICAL_LIMIT
 */
MCP9808.prototype.getAlertMode = function () { ... }

/* set the alert mode, Allowed values . Possible are
 *   MCP9808.DISABLED
 *   MCP9808.CHECK_ALL_LIMITS_COMPARATOR
 *   MCP9808.CHECK_ALL_LIMITS_INTERRUPT
 *   MCP9808.CHECK_CRITICAL_LIMIT
 */
MCP9808.prototype.setAlertMode = function (mode) { ... }

/* returns if a configure temperature alert has occured
 */
MCP9808.prototype.hasAlert = function () { ... }

/* get the lower temperature limit to trigger an alert
 * The default value after reset is 0°C.
 */
MCP9808.prototype.getAlertLowerLimit = function () { ... }

/* Set the lower temperature limit to trigger an alert.
 * @param temperature lower limit in celsius
 */
MCP9808.prototype.setAlertLowerLimit = function (temperature) { ... }

/* get the upper temperature limit to trigger an alert
 * The default value after reset is 0°C.
 */
MCP9808.prototype.getAlertUpperLimit = function () { ... }

/* Set the upper temperature limit to trigger an alert.
 * @param temperature upper limit in celsius
 */
MCP9808.prototype.setAlertUpperLimit = function (temperature) { ... }

/* get the critical temperature limit to trigger an alert
 * The default value after reset is 0°C.
 */
MCP9808.prototype.getAlertCriticalLimit = function () { ... }

/* Set the critical temperature limit to trigger an alert.
 * @param temperature critical limit in celsius
 */
MCP9808.prototype.setAlertCriticalLimit = function (temperature) { ... }

// Read 1 byte from register reg
MCP9808.prototype.read8 = function (reg) { ... }

// Read two  bytes from register reg and combine to unsigned integer
MCP9808.prototype.read16 = function (reg) { ... }

// Write one byte (value) to register reg
MCP9808.prototype.write8 = function (reg, value) { ... }

// Write an unsigned integer value (two bytes) to register reg
MCP9808.prototype.write16 = function (reg, value) { ... }

exports.connect = function (i2c, a2a1a0Pins) { ... }

Buying

• Adafruit

Links

• Manufacturer
• Datasheet