Temperature Data Logger
Created: Oct 11, 2016
No description available.
This reference design is a temperature data logger used to evaluate the MCP9800 temperature sensor. It uses a PIC10F202 MCU to read the temperature data using I2C communication. Microchip provides several microcontroller product lines with Master Synchronous Serial Port (MSSP) modules that include the I2C interface mode. This module implements all master and slave functions and simplifies the firmware development overhead. The circuit shows a typical application using the PIC10F202 as a master to control other Microchip slave products, such as EEPROM and the MCP9800 temperature sensor connected to the bus.
The MCP9800 temperature data logger, once programmed, will log temperature measurements for a predetermined amount of time until the 24LC16B is fully programmed with temperature data (number of temperature readings). Each sample uses one byte of memory. The intervals can be changed in the firmware by changing the TIMEOUTVAL variable. The firmware will take measurements for approximately 45 minutes (approximately 1 sample/sec). The TIMEOUTVAL variable may be modified to put longer delays between measurements. Any value between 1 (default) and 255 may be used to vary the sample rate. The higher the number is the slower the sample rate. The TIMEOUTVAL variable is approximately the number of seconds delay between measurements.
The circuit can then be placed into a SEEVAL 32 Serial EEPROM Evaluation tool and the content can be read and stored into a hex file. The circuit also has the MCP101; a voltage supervisory device designed to keep a microcontroller in Reset until the system voltage has reached the proper level and stabilized. It also operates as protection from brownout conditions when the supply voltage drops below a safe operating level.