TMP114: I2C bus issue

johan lantz

Part Number: TMP114

Using a STM32H735 devkit with TMP114 sensor connected to the devkit. Scanning for slaves on the i2c bus only detect the onboard audio chip and no TMP114 devices. The sensor have been used in another project with another platform and work fine. But I cannot seams to get any response at all. I use standard mode 100kHz with pullup and no pullup. I can see that I have both data and clock on the bus. Is this device using any specific timing or operation that differs from normal operation?

3 months ago

0 Ren Schackmann 3 months ago

TI__Mastermind 38805 points

Hi Johan,

My TMP114 sample responds to the linux command i2cdetect under address 0x48. Of course, your TMP114's address will depend on the orderable variant that you have, but it is compatible with standard scanning tools.

Did you solder your TMP114? As a BGA device, it can be challenging to solder manually, and it will be difficult to verify connectivity at the TMP114. Have you checked another sample?

thanks,

ren

0 johan lantz 3 months ago in reply to Ren Schackmann

Prodigy 30 points

We have 4 devices soldered onto a FPC, I also think this was bought as assembled component with cables you can attach to your board. The FPC was used in anther project and it did work. So no issue with soldering. I do know about the A,B,C,D variants of the device but I scan slave address 0-FF so if the device is working it should be detected.

0 Ren Schackmann 3 months ago in reply to johan lantz

TI__Mastermind 38805 points

While I strongly suspect you have a connectivity issue, I'll have to ask for oscilloscope captures of the bus activity to debug this further. Please double-check your connections while you're at it.

thanks,

ren

0 johan lantz 3 months ago in reply to Ren Schackmann

Prodigy 30 points

I have verified that everything is okay and after some swapping of sensors (some connection was not fully connected also). it now acknowledge the data address and register pointer and output 2 bytes. But independent what resister I read it always return FFFF.

0 Ren Schackmann 3 months ago in reply to johan lantz

TI__Mastermind 38805 points

I'm glad to hear you resolved the connectivity. I'll need to see a capture of the bus activity to understand what is being sent to the device. Note that this device requires the use of ReStart after write pointer, as shown in Figure 8-14. This only impacts read operations.

thanks,

ren

0 johan lantz 3 months ago in reply to Ren Schackmann

Prodigy 30 points

Looking at the flow its a normal Philips i2c protocol and i use normal hal api to transfer and receive data. Is there anything i have missed here?

0 Ren Schackmann 3 months ago in reply to johan lantz

TI__Mastermind 38805 points

It's possible to perform STOP (P) after write pointer transaction. Most of our temp sensors would store the written pointer indefinitely. TMP114 will not retain the pointer, and requires the write/restart without stop to perform read transactions.

ren

0 johan lantz 3 months ago in reply to Ren Schackmann

Prodigy 30 points

I do not have the plot for the I2C transaction at the moment. But when I worked on it look okay. We are using STM32 as MCU and in the link below its basically run the same setup as I do.

https://www.digikey.be/en/maker/projects/getting-started-with-stm32-i2c-example/ba8c2bfef2024654b5dd10012425fa23

0 Ren Schackmann 3 months ago in reply to johan lantz

TI__Mastermind 38805 points

Try using HAL_I2C_Mem_Read

https://community.st.com/t5/stm32-mcus-products/support-for-repeated-start-in-stm32-hal-i2c-library/td-p/429213

thanks,

ren

0 johan lantz 3 months ago in reply to Ren Schackmann

Prodigy 30 points

This is concerning, because we will use a I2C Mux between the TMP114 and platform so this trick will not work. I just now before the custom hardware arrives try to test the driver before to set the correct handling for the TMP114. In the example i send as a link it shows that with a normal HAL I2C driver it should work but it dose not.

0 Ren Schackmann 3 months ago in reply to johan lantz

TI__Mastermind 38805 points

TMP114 is compatible with I2C Mux. Do you have further questions for me?

thanks,

ren

+1 johan lantz 3 months ago in reply to Ren Schackmann

Prodigy 30 points

I guess we have to see if it works on the custom hardware.

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TMP114: I2C bus issue