Results

Ease of Use

Our thermometer is very easy to use. The increment and decrement buttons mimic those of an alarm clock. When any of these buttons are held down for a long time (> 1 sec), the increment and decrement amounts change from a step size of .1° to .5°. Similarly, you can change temperature scales simply by repeatedly pressing a toggle button. The recorded maximum and minimum temperatures are also easily displayed by pressing the display max or display min push buttons.

Accuracy

Our digital thermometer is accurate in measuring temperatures to within .1°. Fahrenheit (°F) is used as the base temperature scale, and all conversions are made from this temperature scale. Formulas for computing the other scales are as follows:

°C = 5/9 (°F - 32)
°K = °C + 273 = 5/9 (°F - 32) + 273
°R = °F + 460

We tested our conversion source code for several temperature values in °F, and the corresponding values in °C, °K, and °R were all within .2° of the expected values, but mostly within .1°...(see table below) Pretty good considering minor truncations are unavoidable when performing divisions such as 1/9. Notice, too, how these slight aberrations only occur for the Celsius and Kelvin values.

Accuracy Analysis for Temperature Conversion
°F (base value)	Measured °C	Expected °C	Measured °K	Expected °K	Measured °R	Expected °R
65.0	18.3	18.33	291.3	291.33	525	525
71.9	22.1	22.166	295.2	295.166	531.9	531.9
75.0	23.8	23.88	296.8	296.88	535	535
80.3	26.7	26.833	299.7	299.833	540.3	540.3

Extendability

As mentioned earlier, the feature of being able to detect temperature boundaries set by the user makes our digital thermometer very extendable. Port pins B[7] and B[6] go active low when it is either too hot or too cold, respectively. Thus, this could act as the control signal to drive/trigger an external device such as a fan, heater, safety valve, etc...