1300 Henley Court Pullman, WA 99163 509.334.6306 www.digilentinc.com PmodTMP2 Reference Manual Revised May 24, 2016 This manual applies to the PmodTMP2 rev. B Overview 2 The PmodTMP2 is an ambient temperature sensor powered by the Analog Devices ADT7420. Through the I C interface, users may appreciate a resolution of 0.0078C through 16 bits of data. Features include: 16-bit ambient temperature sensor Typical accuracy better that 0.25C 240 ms continuous conversion time Programmable over and under- temperature control pins No calibration required Small PCB size for flexible designs 1.0 0.8 (2.5 cm 2.0 cm) 24-pin connector with I2C interface Follows Digilent Pmod Interface Specification Library and example code available in resource center The PmodTMP2. 1 Functional Description 2 The PmodTMP2 uses an 8-pin connector that allows for communication via I C, and provides pins to daisy-chain 2 2 the PmodTMP2 to other I C devices. The PmodTMP2 also provides two 2-pin headers for selecting the I C address of the chip, and two 2-pin headers for controlling external devices based upon temperature thresholds defined by the user in software. 2 Interfacing with the Pmod 2 The PmodTMP2s onboard ADT7420 chip acts as a slave device using the industry standard I C communication 2 scheme. To communicate with the PmodTMP2 device the I C master 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 2 desired register address to ADT7420, then send an I C restart condition, and send a new read request to the Copyright Digilent, Inc. All rights reserved. DOC : 502-221 Page 1 of 3 Other product and company names mentioned may be trademarks of their respective owners. PmodTMP2 Reference Manual 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. 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) Table 1. Interface connector signal description. Header J1 Jumper Blocks Pin Signal Description Jumper Block State Description 1 & 5 SCL Serial Clock JP1 Open/Shorted Address bit 0 high/low 2 & 6 SDA Serial Data JP2 Open/Shorted Address bit 1 high/low 3 & 7 GND Power Supply Ground User Outputs 4 & 8 VCC Positive Power Supply Header Name Pin Name Description J2 CT Critical Threshold Output J3 INT Interrupt Output Table 2. Pinout description table. 2 2 2 The I C interface standard uses two signal lines. These are I C data and I C clock. These signals map to the serial data (SDA) and serial clock (SCL) respectively on the ADT7420. Addresses JP2 JP1 Address Open Open 0x4B (0b1001011) Open Shorted 0x4A (0b1001010) Shorted Open 0x49 (0b1001001) Shorted Shorted 0x48 (0b1001000) Table 3. I2C address selection. 2 The PmodTMP2 I C bus can be set to use one of four valid addresses. The top five bits of the address are fixed, and the two least significant bits are taken from the jumper states of JP2 and JP1. JP2 corresponds to bit one of the address while JP1 corresponds to bit zero. An open jumper corresponds to a one in the address while a shorted jumper corresponds to a zero. For example, when JP2 and JP1 are open the device uses the address 0x4B (0b1001011). Copyright Digilent, Inc. All rights reserved. Page 2 of 3 Other product and company names mentioned may be trademarks of their respective owners.