Inquiry regarding Power-Up/Reset Format on TMP102

Atsushi Okui

Genius 4015 points

Other Parts Discussed in Thread: TMP102, ADS1013

Hello, all

Now we have one inquiry regarding Power-Up/Reset Format on TMP102 from our customer.

Please refer to the item below, and feedback us with your comment.

When referring page 7 CONFIGURATION REGISTER of this datasheet, we could find each initial value on register.

However, on customer's board, the initial register values which were read by I2C were not same as the description. e.g. R1 and R0 were both 0.

Please find the captured I2C communication waveform for your reference.

Please let us clarify how to read each initial registers properly.

We thank you in advance for your information.

Best regards,

over 11 years ago

0 Abhishek Muppiri over 11 years ago

TI__Expert 7945 points

Hello Atsushi-san,

Thanks for providing the waveforms, this will help us in resolving our customers issue.

Please go through the picture where I have marked and added description for each byte transmitted. Instead of sending the Configuration register address, customer is sending "Temperature register address" in the pointer register field (circled in green) due to which when they perform I2C read subsequently, they are reading 24.0625degreeC.

Please advice the customer to send 0x01 (Configuration Register Address) in place of Temperature register address. Communication format and other timing conditions looks good so once this change is implemented customer should be able to read the Config Register fields.

I hope you were able to follow my description, if you have any further questions please don't hesitate to contact me.

Best Regards,

Abhi Muppiri

Applications Engineer

MHR- Sensing Products

Texas Instruments

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0 Atsushi Okui over 11 years ago in reply to Abhishek Muppiri

Genius 4015 points

Abhi-san,

Thank your for your information.

Now we are asking them to measure with sending configuration register address.

Meanwhile, we have inquired one additional question regarding temperature register, please refer to the item below and feedback us with your comment.

24.0625degreeC seems to be exchanged into binary as 00000001 10000001, with 1LSB=0.0625 conversion table.

However, the scope showed the binary as 0011000 00000000.

Could you help us how to make the conversion table correctly with the scope?

We thank you once again for your information.

Best regards,

0 Abhishek Muppiri over 11 years ago in reply to Atsushi Okui

TI__Expert 7945 points

Hello Atsushi-san,

I have decoded the temperature register waveform bit by bit below.

00011000_00000000 corresponds to 24degreeC. You can cross check this with Table.5 of the datasheet.

There is no 0.0625degC, it looks like I misread the NACK in end as the LSB value bit 1 in my previous picture. I hope its clear to you now.

Regards,

Abhi

0 Atsushi Okui over 11 years ago in reply to Abhishek Muppiri

Genius 4015 points

Abhishek-san,

Thank you for your continuous support towards the inquiries from our customer.

I have some additional inquiries regarding configuration register and temperature register individually. Please refer to the items below, and feedback us with your comment.

1) Configuration register

As they tried to send 0x01 (Configuration Register Address) after power on, the acquired data was still not as same as what we expect (01100000 10100000).

Please see the captured waveform as following;

2) Temperature register

As they are trying to acquire temperature data from TMP102 frequently, on sometimes the acquired temperature data was dropped than usual (normally, the environmental temperature is approximately 20 degreeC.)

Please see the captured waveform on this case as well.

Please let us clarify how to resolve each inquiries in order to have further proceed.

We thank you once again for your information.

Best regards,

0 Abhishek Muppiri over 11 years ago in reply to Atsushi Okui

TI__Expert 7945 points

Atsushi-san,

I agree with you, both the register values presented in the wave forms don't look anywhere close to what they are supposed to be. Are you sure these are the values obtained after the device is powered On?

I don't suspect any I2C issues since you are obtaining Acknowledges from TMP102 and the host.

The very first waveform that you had presented has 24degC and now its no where close to to 20degC. Did anything change in terms of the setup? Is this a repeatable issue?

Please provide me these inputs since they will help me debug further.

Regards,

Abhi

0 Atsushi Okui over 11 years ago in reply to Abhishek Muppiri

Genius 4015 points

Abhishek-san,

Thank you for your reply on additional inquiries.

Our customer could find these root cause by themselves, that the I2C device address of 2 ADCs which are mounted on this system board are same, which resulted in fail to acquire correct informations.

After modified this, the acquired informations are correct.

Thank you once again for your support.

Best regards,

0 Abhishek Muppiri over 11 years ago in reply to Atsushi Okui

TI__Expert 7945 points

Hello Atsushi-san,

Glad that the issue was resolved. I understand that there was I2C bus contention. I just want to make sure i understand this correctly... is the address of TMP102 and one ADC was same? Or did the 2 ADC's and TMP102 shared the same I2C address?

Thanks,

Abhi

0 Atsushi Okui over 11 years ago in reply to Abhishek Muppiri

Genius 4015 points

Abhishek-san,

Sorry for late response on your question.

Customer said that they used TMP102 and ADS1013 on same I2C bus line as parallel.

Since A0 pin on TMP102 and ADDR pin on ADS1013 were both connected to GND, the I2C address of both devices were indicated as 1001000, which resulted in I2C bus contention.

I hope this information could help you to clarify the detailed root cause.

Best regards,

Sensors

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Inquiry regarding Power-Up/Reset Format on TMP102