D
AT
A BUS
TOP VIEW
LM35
GND
VOUT
VCC
VCC-5V
J25
RE1
RE2
TS2
VCC
GND
VOUT
1 2 3
Figure 16-5:
LM35
connected
to RE1 pin
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
obtain convenient Centigrade scaling.
It has a 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. EasyPIC
™
v7 enables you to
get analog readings from the LM35
sensor in restricted temperature range
from +2ºC to +150ºC. Board provides 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
J25
. Jumper connects the sensor
with either
RE2
or
RE1
microcontroller
pins.
EasyPIC
™
v7 enables you to get analog readings from the LM35 sensor using
RE1
or
RE2
microcontroller pins. The selection of either of those two lines
is done using
J25
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 accidently 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.
Figure 16-1:
LM35 not
connected
Figure 16-2:
LM35 placed
in socket
Figure 16-3:
LM35
connected
to RE1 pin
Figure 16-4:
LM35
connected
to RE2 pin
Enabling LM35 Sensor
LM35 - Analog
Temperature Sensor
page 29
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