122-28176 Parallax Inc, 122-28176 Datasheet - Page 204

• Manufacturer Part Number: 122-28176
• Description: GUIDE STUDENT PROCESS CONTROL
• Manufacturer: Parallax Inc

Specifications of 122-28176

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Propeller Education (PE) Kit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

In terms of byte value, the resolution is 255/1.25 V or 204/V. Our high temperature of
interest, 120 °F (1.2 V), would provide a byte value of 1.2 V x 204 = 244.8 or 245. The
low temperature of interest, 70 °F (0.7 V), would provide a byte value of 0.7 x 204 =
142.8 or 143. So the temperature range of interest covers a byte value change of
245−143 = 102. The majority of our available byte values (0 to 101 and 246 to 255) are
still outside the temperature range of interest.
What line equation would best serve the needs of the monitoring and control system?
Figure 6-9 is the ideal line needed to convert the temperature range of interest to a digital
value for measurement. The temperature range of 70 °F (0.7 V) to 120 °F (1.2 V) is
amplified and covers 0 to 5 volts into the ADC for byte values of 0 to 255.
Let's analyze the line and develop the line equation.
Since the line does not cross at (0,0), b can be calculated given any single known point,
such as 0.7 V and 0 V or 1.2 V and 5 V.
y = mx + b
m = ∆Output/∆Input = (5−0 V)/(1.2−0.7 V) = 5 V/0.5 V = 10
Figure 6-9
Ideal Conversion for
70 °F-120 °F