Thread starter
#1

Hi ETO

I am using an automotive coolant temperature sensor on a 16F1827.

The sensor is wired to +5 volts and AN0 with a 4K7 ohm pull down resistor.

At 32 Degrees F the sensor is 6000 ohms.

At 77 Degrees F the sensor is 1700 ohms.

At 212 Degrees F the sensor is 176 ohms.

I would like to display degrees Fahrenheit on the LCD but the ADC readings seem to change exponentially.

What kind of formula do I need to convert the output?

I am using Hi-Tech C so there are plenty of functions to work with.

Or could I hook it up differently to get a more linear output?

These are my readings and a graph.

I am using an automotive coolant temperature sensor on a 16F1827.

The sensor is wired to +5 volts and AN0 with a 4K7 ohm pull down resistor.

At 32 Degrees F the sensor is 6000 ohms.

At 77 Degrees F the sensor is 1700 ohms.

At 212 Degrees F the sensor is 176 ohms.

I would like to display degrees Fahrenheit on the LCD but the ADC readings seem to change exponentially.

What kind of formula do I need to convert the output?

I am using Hi-Tech C so there are plenty of functions to work with.

Or could I hook it up differently to get a more linear output?

These are my readings and a graph.

Code:

```
TEMP READING
30 462
35 480
40 502
45 544
50 580
55 595
60 615
65 650
70 695
75 726
80 740
85 767
90 786
95 810
100 828
105 844
110 855
115 873
120 892
125 910
130 922
135 931
140 936
145 940
150 943
155 952
160 960
165 968
170 974
175 978
180 983
185 987
190 999
195 991
200 995
205 997
210 998
```