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TMP275 stuck with one value

Josip Martinaga
Prodigy 20 points
Other Parts Discussed in Thread: TMP275

Working on remote temperature measurement project using multiple TMP275 scattered around the warehouse.

Connected 90 units so far, all but one working well. This one looks like it is stuck at value of measured temperature 2#0111 1111 1111 0000.

Checked the communication, no errors neither on writing nor reading registers (writing only reg 01 - 03)

Tried to switch reading registers in circle, from 00 to 02 to 03, back to 00. All communications done well, registers 02 and 03 read wright, reg 00 always returns value above.

Could you please help with some suggestions.

PS

Although it is only one chip out of 100, I still believe it might be I am doing something wrong, not being the bad chip.

Than you.

  • 0
    TI__Expert 7945 points

    Hello Josip,

    You are reading +128deg C, which means that the internal ADC voltage is railing to the max value. Could you try the following things:

    1. Please make sure the voltage levels on A0,A1,A2 pin correspond  to your internal I2C slave address configurations. 

    2. Check if replacing this part solves the problem.

    Hopefully, this will give us insights behind the underlying issue. Also, how many host devices are you using to access these 90 TMP275's

    Thanks,

    Abhi

  • 0 in reply to Abhishek Muppiri
    Prodigy 20 points

    Hello Abhi,

    Thanks for your quick response.

    Yes, voltages on addressing pins are OK. Matter a fact I tried all 8 addresses of the device (several times) and device always correctly responds at chosen address and always with the this same value.

    For replacing the part I'll have to wait for next bunch of sensors to arrive since all devices I ordered for this project are already soldered on their PCBs.

    90 TMP275s are in fact installed within two buildings (44 + 46). At each this two sites I use 8 x I2C Mux device which gives me individual access to each sensor.

    B Regards,

    Josip