S1C60N02 TECHNICAL MANUAL
EPSON
83
APPENDIX: TECHNICAL INFORMATION
Computation
method of displayed
temperature by
linear approximation
The following shows the linear approximation equation to derive
the displayed temperature.
Displayed temperature (°C) = (Count after A/D conversion - Count for
minimum in the temperature range)
× linear approximation coefficient +
minimum value of the temperature range
This equation derives the displayed temperature. The following
shows the method. First, each value is described.
[Count value after A/D conversion]
This is the up counter value after an A/D conversion.
[Count for the minimum value of the temperature range]
[Minimum value of the temperature range]
To derive the displayed temperature by the linear approximation,
the temperature range must be determined for the linear approxi-
mation. In this example, the measured temperature range is -30 to
70°C.
If the temperature range for the linear approximation is set for
every 10°C, the temperature range is -30 to -20°C, -20 to -10°C,
and so on. The smallest value of each temperature range segment
is the minimum value of the temperature range. The largest value
is the maximum value of the temperature range.
The count value for the minimum value for the temperature range
is expressed by the following equation:
A/D converter count value =
fCR2
× up counter initial value
fCR1
=
(K/CR2) × up counter initial value
(K/CR1)
=
R1
× up counter initial value
R2
By substituting R2 (Thermistor resistance), R1 (standard resist-
ance), and the up counter initial value with actual values, the
count value for the minimum of the temperature range is obtained.
[Linear approximation coefficient]
The linear approximation coefficient is the value that shows how
many degrees (centigrade) for one count in the temperature range.
The linear approximation coefficient is expressed by the following
equation:
Linear approximation coefficient =
Temperature range
Count for max. of temperature range - Count for min. of temperature range
(As you can see, the temperature range is smaller, the precision is
higher.)