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Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.

Overview

The PmodTMP2 is a temperature sensor and

thermostat control board built around the

Analog Devices ADT7420.

Features include:

•

Up to 16-bit resolution

•

Typical accuracy better than 0.25 °C

•

I

addresses

•

240ms continuous conversion time

•

Support for 3.3v and 5v interfaces

•

No calibration required

•

Programmable

overtemperature/undertemperature

control pins.

Functional Description

The PmodTMP2 uses an 8-pin connector that

allows for communication via I

pins to daisy-chain the PmodTMP2 to other I

devices. The PmodTMP2 also provides two 2-

pin headers for selecting the I

chip, and two 2-pin headers for controlling

external devices based upon temperature

thresholds defined by the user in software.

I

The PmodTMP2’s onboard ADT7420 chip acts

as a slave device using the industry standard

I

with the PmodTMP2 device the I

device must specify a slave address (0x48-

0x4B) and a flag indicating whether the

communication is a read (1) or a write (0). This

is followed by the actual data transfer. For the

ADT7420, the data transfer should consist of

the address of the desired device register

followed by the data to be written to the

specified register. To read from a register the

master must write the desired register address

to ADT7420, then send an I

condition, and send a new read request to the

ADT7420. If the master does not generate a

restart condition prior to attempting the read,

then the value written to the address register

will be reset to 0x00.

As some registers stored 16-bit values as 8-bit

register pairs, the ADT7420 will automatically

increment the address register of the device

when accessing certain registers such as the

temperature registers and the threshold

registers. This allows for the master to use a

single read or write request to access both the

low and high bytes of these registers. A

complete listing of registers and their behavior

can be found in the ADT7420 datasheet

available on the Analog Devices web site.

The I

lines. These are I

signals map to the serial data (SDA) and serial

clock (SCL) respectively on the ADT7420.

Connector J1 – I2C Communications

Pin

Signal

Description

1, 2

SCL

I2C Clock

3, 4

SDA

I2C Data

5, 6

GND

Power Supply Ground

7, 8

VCC

Power Supply (3.3V/5V)

Interface Connector Signal Description