TMP117: Issues reading chip ID when two tmp devices are connected

KrishnaD

Part Number: TMP117

I am using two tmp117 in my custom board design with one board A0 pin connected to the ground and other board A0 pin is pulled high. The board with the A0 pin connected to the ground works fine but when I try to address the other one with address 0x92, I am unable to read the chip ID. Is there an issue with my addressing or connection for the second tmp sensor?

over 5 years ago

0 Brandon Fisher94 over 5 years ago

TI__Mastermind 28070 points

Hi Krishnaveni Das,

Your addressing is correct, assuming this is the write to the pointer register on that device. It seems like you may not be getting an acknowledge from the second device. Are you able to capture an image of the I2C Transaction on an oscilloscope or logic analyzer?

Best Regards,
Brandon Fisher

0 KrishnaD over 5 years ago in reply to Brandon Fisher94

Intellectual 350 points

Hello Brandon,

Thank you for the reply. Attached a .png of the I2C transaction on an oscilloscope. sorry for the distortions.

0 Brandon Fisher94 over 5 years ago in reply to KrishnaD

TI__Mastermind 28070 points

Hi Krishnaveni Das,

You are not receiving an acknowledge from the slave here. This command is a read using address 0x27 (0x13 interpreted as 7-bit). Can you double check how you are setting the address for the TMP117?

Best Regards,
Brandon Fisher

0 KrishnaD over 5 years ago in reply to Brandon Fisher94

Intellectual 350 points

Hello Brandon,

I am using address 0x92 while writing to the pointer register. I am still not getting an acknowledgement.

0 Brandon Fisher94 over 5 years ago in reply to KrishnaD

TI__Mastermind 28070 points

Hi Krishnaveni,

The transaction I see here is definitely receiving a NACK, but the address it is sending is 0x25 (or a read from a device at 0x12 when using 7 bit + r/w format). Please see the text on the image below for my reading of this waveform. The TMP117 will not ACK for this address.

Can you share the relevant portion of your code where you perform this transaction?

Best Regards,
Brandon Fisher

0 Brandon Fisher94 over 5 years ago in reply to Brandon Fisher94

TI__Mastermind 28070 points

Hi Krishnaveni,

Any luck getting this to work?

Best Regards,
Brandon Fisher

0 KrishnaD over 5 years ago in reply to Brandon Fisher94

Intellectual 350 points

Hello Brandon,

Sorry for the late reply. I fixed my addressing and got the response. Thank you so much for the support.

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TMP117: Issues reading chip ID when two tmp devices are connected