Temperature range

Display of temperature between -55 and +124 deg C (-67 to 255 deg F)with 0.1 degree resolution between -10 and 100 degrees.

Thermostat settings between 1 and 100 deg C (34 to 212 deg F.)

Features

• Simple,cheap,compact design, few components, no surface-mount types.
• Uses an accurate digital sensor to avoid the need for calibration.
• Low power consumption
• Uses a modern Microchip PIC 18F1320 microcontroller
• Temperature sensor is accurate to +/- 0.5 degree Centigrade with 0.1 degree C or F display resolution over most of the range.
• Thermostat is easily adjusted in +/- 1 degree Centigrade or Fahrenheit intervals (all settings saved in memory)
• Adjustable thermostat cycle delay to help reduce wear on heater/cooler
• Adjustable thermostat temperature hysteresis to reduce heater/cooler wear.
• Facility to automatically turn-off the heater/cooler while a door is left open (For Energy saving)
• Under/Over temperature alarm LED indication
• Selectable Celsius or Fahrenheit temperature display
• Minimum and Maximum temperatures are logged for display.

Firmware info

The firmware for this project is written in assembler language.
The microcontroller currently determines if a DS18S20 or DS18B20 sensor is being used.
(It should also work with the old original DS1820 sensors (but with only 0.5 deg display resolution), although I do not have one to test it with.
Each temperature reading is CRC validated. I have experienced no errors with the readings, but decided the CRC checking was worth implementing as a safeguard.

Source: unusualelectronics