TMP112, temperature sensor by Texas Instrument, with very interesting features as
a) SOT563 Pacakge (1.6mm x 1.6mm) is 68% smaller than SOT23.
b) Accuracy of 0.5C
c) Low quiescent of 10uA active and 1uA sleep
d) 12 bit resolution (0.0625C)
e) Supply range 1.4 to 3.6V
The i2c algorithm that we are using to sense the temperature
sensor is as
A) Should be
in reset state while changing some register content. (check in datasheet)
B) Set the IIc
master mode with synchronous setting.
C) Set IIc
clock equal to sub master clock
D) Set some
divider smclk/x = 100khz (can be varied as per requirement up to 400khz)
E) Set the
slave address in 7 bit format
F) Disable or
enable the interrupts
G) Disable the
reset state
a) Again put
in reset mode
b) Generate
the stop condition after transmission of 1 byte automatically.
c) Disable
reset mode
d) Send the
start condition, it will also send the slave address.
e) Wait until
transmission is finished
f) Send the
register we need to read from and wait till transmission is done
g) Set IIC
write operation in receiver mode to generate auto stop after two bytes are
received.
TMP112
sensor gives 16 bits of data
h) Setup for
repeated start
i) Receive
two bytes of data
j) Convert
according to the formula
(50°C) / (0.0625°C / LSB) = 800 = 320h = 0011
0010 0000
0011 0010 0000 = 320h = 800 × (0.0625°C / LSB)
= 50°C
(|–25°C|) / (0.0625°C / LSB) = 400 = 190h = 0001
1001 0000 Two's complement format: 1110 0110 1111 + 1 = 1110 0111 0000