Lm35 - Analog Temperature Sensor - mikroElektronika EasyAVR v7 User Manual

LM35 - Analog
Temperature Sensor
The LM35 is a low-cost precision
integrated-circuit temperature sensor,
whose output voltage is linearly
proportional to the Celsius (Centigrade)
temperature. The LM35 thus has an
advantage over linear temperature
sensors calibrated in ° Kelvin, as the
user is not required to subtract a large
constant voltage from its output to
Enabling LM35 Sensor
1 2
Figure 15-1: Figure 15-2:
LM35 not LM35 placed
connected in socket
EasyAVR v7 enables you to get analog readings from the LM35 sensor using
™
PA7 or PB4 microcontroller pins. The selection of either of those two lines
is done using J19 jumper. When placing the sensor in the socket make sure
that half-circle on the board's silkscreen markings matches the rounded part of
the LM35 sensor. If you accidentally connect the sensor the other way, it can
be permanently damaged and you might need to replace it with another one.
During the readings of the sensor, make sure that no other device uses the
selected analog line, because it may interfere with the readings.
EasyAVR
v7
obtain convenient Centigrade scaling.
It has a linear +10.0 mV/°C scale factor
and less than 60 μA current drain. As it
draws only 60 μA from its supply, it has
very low self-heating, less than 0.1°C
in still air. EasyAVR v7 enables you
™
to get analog readings from the LM35
sensor in restricted temperature range
from +2ºC to +150ºC. Board provides
3 4
Figure 15-4:
Figure 15-3:
LM35 LM35
connected connected
to PB4 pin to PA7 pin
a separate socket (TS2)
for the LM35 sensor in
TO-92 plastic packaging.
Readings are done with
microcontroller using single
analog input line, which is
selected with jumper J19. Jumper
connects the sensor with either PA7
or PB4 microcontroller pins.
VCC
VOUT
GND
PB4
PA7
C23
100nF
J19
Figure 15-5:
LM35
connected
to PA7 pin
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