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Data Logger



This is a fairly simple device that logs data to external EEPROM and sends it via RS232. I use it to log
temperature data. It has three modes. The first mode displays the temp on an LCD without any logging. The
second mode displays the temp and writes it to EEPROM every 7 seconds or so. The third mode reads the data
from EEPROM and sends it through the serial port. It also reports the low, high and number of temperatures
read from EEPROM.

I was using a 16F628, but ran out of ROM, so I upgraded to a 16F648A. The 648A is pin compatible, but has
double the rom space. The floating point math for celsius to fahrenheit and float to string conversions
uses almost 2k alone. I also use a 1-wire 18B20 temperature sensor, a MAX232 compatible serial line driver,
and a 24LC256 256k serial EEPROM. It's all written in CCS (awesome C compiler).