Datasheet
PmodTC1™ Board Reference Manual
Copyright Digilent, Inc. All rights reserved.
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Page 3 of 3
Table 3 below is the pin mapping of the output pins on the PmodTC1 that connect to a host board.
2.1 Digital Temperature Data Format
Two tables (Tables 4 & 5 from the MAX31855 datasheet) are provided below to show the temperature that
corresponds to the two's compliment bit values received by the host board.
The on-board chip on the PmodTC1 requires at least 200 ms to power up before being able to conduct accurate
temperature readings. Each temperature conversion takes up 100 ms to complete and outputs a voltage (to then
be converted into a digital value) by the following linear equation (assuming a virtual reference point of 0°C):
V
OUT
= (41.276 μV/°C) × (T
R
- T
AMB
)
Where V
OUT
is the thermocouple output voltage in μV, T
R
is the temperature of the remote thermocouple junction
(the cold-junction) in °C, and T
AMB
is the temperature of the thermocouple itself in °C.
Any external power applied to the PmodTC1 must be within 3.0V and 3.6V; It is recommended that Pmod is
operated at 3.3V.
3 Physical Dimensions
The pins on the pin header are spaced 100 mil apart. The PCB is 1 inch long on the sides parallel to the pins on the
pin header and 0.8 inches long on the sides perpendicular to the pin header.
Pin
Signal
Description
1
CS
Active Low Chip Select
2
N/A
N/A
3
MISO
Serial Data Out
4
SCLK
Serial Clock
5
GND
Power Supply Ground
6
VCC
Power Supply (3.3V)
Temperature (°C)
Digital Output (D31-D18)
+1600.00°C
0110 0100 0000 00
+1000.00°C
0011 1110 1000 00
+100.75°C
0000 0110 0100 11
+25.00°C
0000 0001 1001 00
0.00°C
0000 0000 0000 00
-0.25°C
1111 1111 1111 11
-1.00°C
1111 1111 1111 00
-250.00°C
1111 0000 0110 00
Temperature (°C)
Digital Output (D15-D4)
+127.0000°C
0111 1111 0000
+100.5625°C
0110 0100 1001
+25.0000°C
0001 1001 0000
0.0000°C
0000 0000 0000
-0.0625°C
1111 1111 1111
-1.0000°C
1111 1111 0000
-20.0000°C
1110 1100 0000
-55.0000°C
1100 1001 0000
Table 4. 14-bit thermocouple temperature data.
Table 5. 12-bit cold-junction temperature data.
Table 3. Pin mapping of the output pins.
Figure 1. Block diagram of MAX31855 interfacing with a microcontroller over SPI.