A Mongoose library for Microchip's MCP9808 integrated circuit.
Microchip Technology Inc.’s MCP9808 digital temperature sensor converts temperatures between -20°C and +100°C to a digital word with ±0.25°C/±0.5°C (typical/maximum) accuracy.
The MCP9808 comes with user-programmable registers that provide flexibility for temperature sensing applications. The registers allow user-selectable settings such as Shutdown or Low-Power modes and the specification of temperature Alert window limits and critical output limits. When the temperature changes beyond the specified boundary limits, the MCP9808 outputs an Alert signal. The user has the option of setting the Alert output signal polarity as an active-low or activehigh comparator output for thermostat operation, or as a temperature Alert interrupt output for microprocessor based systems. The Alert output can also be configured as a critical temperature output only.
This sensor has an industry standard 400 kHz, 2-wire, SMBus/I2C compatible serial interface, allowing up to eight or sixteen sensors to be controlled with a single serial bus.
These features make the MCP9808 ideal for sophisticated, multi-zone, temperature-monitoring applications.
See datasheet for implementation details.
A great place to buy a ready made and tested unit is at Adafruit.
An example program using a timer to read data from the sensor every 5 seconds:
#include "mgos.h"
#include "mgos_i2c.h"
#include "mgos_mcp9808.h"
static struct mgos_mcp9808 *s_mcp9808;
static void timer_cb(void *user_data) {
float temperature;
temperature=mgos_mcp9808_getTemperature(s_mcp9808);
LOG(LL_INFO, ("mcp9808 temperature=%.2f", temperature));
(void) user_data;
}
enum mgos_app_init_result mgos_app_init(void) {
struct mgos_i2c *i2c;
i2c=mgos_i2c_get_global();
if (!i2c) {
LOG(LL_ERROR, ("I2C bus missing, set i2c.enable=true in mos.yml"));
} else {
s_mcp9808=mgos_mcp9808_create(i2c, 0x40); // Default I2C address
if (s_mcp9808) {
mgos_set_timer(5000, true, timer_cb, NULL);
} else {
LOG(LL_ERROR, ("Could not initialize sensor"));
}
}
return MGOS_APP_INIT_SUCCESS;
}
This project is not an official Google project. It is not supported by Google and Google specifically disclaims all warranties as to its quality, merchantability, or fitness for a particular purpose.