Arduino MCP9800 Temperature Sensor Library 1.1.0
https://github.com/JChristensen/MCP9800
README file
Jack Christensen Mar 2014
Introduction
Arduino Library for Microchip MCP9800/1/2/3 2-Wire High-Accuracy Temperature Sensors
A lightweight implementation that exposes all functionality of the Microchip MCP9800/1/2/3 sensors. Temperatures are dealt with in the integer domain to avoid the code size and runtime overhead associated with floating-point. Still, it is straightforward to perform the necessary conversions should the user wish to work in floating-point format.
Temperatures read from the device's registers are returned as °C*16. (If the device resolution is set to less than 12 bits, the corresponding lower order bits are simply returned as zero.) Temperatures can alternately be read as °F*10.
When writing the Hysteresis and Limit-Set registers, the value must be given as °C*2, which corresponds to the internal representation in these registers.
Bit masks for the control register are provided in the MCP9800.h file.
"Arduino Library for Microchip MCP9800/1/2/3" by Jack Christensen is licensed under CC BY-SA 4.0.
Examples
The following example sketch is included with the MCP9800 library:
- MCP9800_EX1: Demonstrates basic reading of ambient temperature in Celsius and Fahrenheit, conversion to floating-point, changing device options via the Cofiguration register, and changing the Limit-Set and Hysteresis registers.
Enumeration
MCP9800_REGS_t
Description
Symbolic names for the MCP9800 registers.
Values
- AMBIENT -- for the Ambient Temperature Register
- HYSTERESIS -- for the Temperature Hysteresis Register
- LIMITSET -- for the Temperature Limit-Set Register
Constructor
MCP9800(uint8_t LS_ADDR_BITS)
Description
Instantiates an MCP9800 sensor object.
Syntax
MCP9800 mySensor(0);
// or
MCP9800 mySensor;Parameters
LS_ADDR_BITS: An unsigned 8-bit integer (uint8_t or byte) representing the least-significant three bits of the I2C device address (i.e. a value between 0 and 7). Defaults to zero if omitted. (Note that some devices in the MCP9800 family allow the user to select the least significant three bits of the address, and some have a fixed address from the factory. See the datasheet for details.)
Methods
begin()
Description
Initializes the library. Call this method once in the setup code.
Syntax
mySensor.begin();
Parameters
None.
Returns
None.
Example
MCP9800 mySensor;
mySensor.begin();readTempC16(MCP9800_REGS_t reg)
Description
Reads one of the three temperature registers from the sensor.
Syntax
mySensor.readTempC16(MCP9800_REGS_t reg);
Parameters
reg: The temperature register to read, AMBIENT, HYSTERESIS or LIMITSET (MCP9800_REGS_t)
Returns
Temperature as degrees Celsius times 16 (int).
Example
MCP9800 mySensor;
mySensor.begin();
int c16 = mySensor.readTempC16(AMBIENT);
float C = c16 / 16.0;readTempF10(MCP9800_REGS_t reg)
Description
Reads one of the three temperature registers from the sensor.
Syntax
mySensor.readTempF10(MCP9800_REGS_t reg);
Parameters
reg: The temperature register to read, AMBIENT, HYSTERESIS or LIMITSET (MCP9800_REGS_t)
Returns
Temperature as degrees Fahrenheit times 10 (int).
Example
MCP9800 mySensor;
mySensor.begin();
int f10 = mySensor.readTempF10(AMBIENT);
float F = f10 / 10.0;writeTempC2(MCP9800_REGS_t reg, int value)
Description
Sets the Temperature Hysteresis Register or the Temperature Limit-Set Register.
Syntax
mySensor.writeTempC2(MCP9800_REGS_t reg, int value);
Parameters
reg: The temperature register to write, HYSTERESIS or LIMITSET (MCP9800_REGS_t). If given the AMBIENT temperature register, no action is taken (AMBIENT is a read-only register).
value: The temperature value to set, in degrees Celsius times two (int)
Returns
None.
Example
MCP9800 mySensor;
mySensor.begin();
mySensor.writeTempC2(HYSTERESIS, 25 * 2); //set hysteresis register to 25°C
mySensor.writeTempC2(LIMITSET, 100 * 2); //set limit-set register to 100°CreadConfig()
Description
Reads the value of the configuration register.
Syntax
mySensor.readConfig();
Parameters
None.
Returns
Configuration register value (byte)
Example
MCP9800 mySensor;
mySensor.begin();
byte config = mySensor.readConfig();writeConfig(uint8_t value)
Description
Writes a value to the configuration register.
Syntax
mySensor.writeConfig(byte value);
Parameters
value: The value to be written to the register. See the MCP9800.h file for symbolic definitions for the bits in the configuration register.
Returns
None.
Example
MCP9800 mySensor;
mySensor.begin();
//set ADC resolution to 12 bits and the fault queue length to 6
byte config = ADC_RES_12BITS | FAULT_QUEUE_6;
mySensor.writeConfig(config);