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TMP421-Q1: How to measure with TMP421AQDCNRQ1 Temperature Sensor

Yonghee Lee
Prodigy 20 points
Part Number: TMP421-Q1
Other Parts Discussed in Thread: SYSCONFIG

Hi, 

I am Yonghee Lee and working as a software engineer at LG Innotek.

 I am going to use TMP421AQDCNRQ1 Temperature Sensor via I2C.

The first thing that I want to ask is how to set the slave address. A0 and A1 pins in our system is connected to ground. Based on the datasheet, I guess it should be 1001 100 and 0x4C in hexadecimal. Please let me know how to set it for I2C.

The second thing is how to transmit command and data for local temperature via I2C. The register map says pointer(0x00) can be used to transmit the local temperature HIGH byte. I am wondering if the sensor transmits one byte data per command or multiple byte data per command.

it would be nice if you have an idea about the questions.

Thank you.

  • 0
    TI__Genius 9675 points

    Hi Yonghee,

    You are correct that the slave address should be set as 0x4C based on A0 and A1 being connected to GND.

    Please see section 8.5.3 (Bus definitions) of the datasheet for two-wire format for Writing, Single-Byte Read and Double-Byte Reads. The Single Byte read will provide 1°C temperature resolutions from the high byte. If further resolution is needed, the low byte can be stored to achieve 0.0625°C resolution. 

    We also have development support through Sysconfig through the link below. You can find c code for the TMP461-Q1 which will be similar to that of the TMP421-Q1.

    https://dev.ti.com/sysconfig/index.html?product=ascstudio

    Jalen