Pmod TMP3 Reference Manual

The Digilent PmodTPM3 (Revision A) is a temperature sensor module built around the Microchip TCN75A. Users may easily measure a wide range of ambient temperatures (-40°C to +125°C) at up to 0.0625 °C of resolution.

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  • Ambient temperature sensor with up to 12-bit resolution
  • Typical accuracy of ±1 °C
  • Programmable temperature alert pin
  • Multiple jumpers for eight selectable addresses
  • 30 ms to 240 ms typical conversion times
  • 2×4-pin port with I2C interface

Functional Description

The Pmod TMP3 utilizes theMicrochip TCN75A to provide users with up to 12 bits of resolution of ambient temperature data.

Interfacing with the Pmod

The Pmod TMP3 communicates with the host board via the I²C protocol. Users may select one of 8 different I²C slave addresses ranging from 0x48 to 0x4F by adjusting the jumpers JP1, JP2, and JP3 to either be at a digital '1' (3.3V) or a digital '0' (GND). A table explaining the different options is provided below:

JP3 JP2 JP1 Slave Address
GND GND GND 0x48 (0b1001000)
GND GND 3V3 0x49 (0b1001001)
GND 3V3 GND 0x4A (0b1001010)
GND 3V3 3V3 0x4B (0b1001011)
3V3 GND GND 0x4C (0b1001100)
3V3 GND 3V3 0x4D (0b1001101)
3V3 3V3 GND 0x4E (0b1001110)
3V3 3V3 3V3 0x4F (0b1001111)

As an I²C device, the serial clock and serial data lines (SCL and SDA, respectively) need to be pulled up to the logic high voltage level through pull-up resistors. The Pmod TMP3 provides two jumper blocks, JP4, and JP5, that users can individually load to pull the two communication lines (JP4 for SDA and JP5 for SCL) up to a logic high voltage. Jumper JP6 enables a pull-up resistor to be used with the output alert pin.

To read from the Pmod TMP3 with its default settings of 9 bits of resolution, users will need to first write to the Pmod TMP3 the register address of the stored data (0x00). Users may then send a restart condition and perform a read operation from the Pmod, reading in the two bytes of information. The 9-bits of temperature data are arranged in a two's complement format, with the first 9 bits in the two bytes consisting of the temperature data and the remaining 7 bits as 0's.

A pinout table of the Pmod TMP3 is provided below:

Pinout Description Table

Header J1 Jumper Blocks
Pin Signal Description Jumper Block State Description
1 & 5 SCL Serial Clock JP1 3V3/GND Address bit 1 high/low
2 & 6 SDA Serial Data JP2 3V3/GND Address bit 2 high/low
3 & 7 GND Power Supply Ground JP3 3V3/GND Address bit 3 high/low
4 & 8 3V3 Positive Power Supply JP4 Enabled SDA pull-up enabled
Header J2 JP5 Enabled SCL pull-up enabled
Pin Signal Description JP6 Enabled Alert pull-up enabled
1 AL Alert Pin
2 GND Power Supply Ground

Any external power applied to the Pmod must be within 2.5V and 5.5V; however, it is recommended that Pmod is operated at 3.3V.

Physical Dimensions

The pins on the pin header are spaced 100 mil apart. The PCB is 1 inch long and 0.8 inches wide.

Additional Information

The schematics of the Pmod TMP3 are available here. Additional information about the Microchip TCN75A including communication modes and specific timings of the chip can be found by checking out its datasheet here.

Example code demonstrating how to get information from the Pmod TMP3 can be found here.

If you have any questions or comments about the Pmod TMP3, feel free to post them under the appropriate section (“Add-on Boards”) of the Digilent Forum.