EVM430-FR6043: Incorrect ADC capture

Megha Shah

Part Number: EVM430-FR6043
Other Parts Discussed in Thread: TIDM-02005,

Hello,

I have been trying to replicate TI's liquid concentration sensing using EVM430-FR6043 and following TIDM-02005. However, I am having trouble achieving the ideal ADC capture response as provided in the documents. Instead, I get a negative linear response different for upstream and downstream transducers. I have attached images of the AD capture response and my board (I already changed the electronics as mentioned in TIDM-02005- 3.1.1.1.1)

Edit- The errors tab on GUI mentions "No signal detected in the upstream and downstream channel" The chamber is filled with water completely to the top. Interestingly a similar ADC capture is obtained when there is no water in the container. I am not sure where I am losing the signal.

Does anyone know the cause of this?

over 2 years ago

0 Evan Lew over 2 years ago

TI__Genius 10010 points

Hi Megha Shah,

Thanks for sharing your question. The ADC capture you have shared does not look correct. The EVM430-FR6043 is configured to do gas measurements by default. You will need to make a small hardware modification on the board to make this work for water. Please see section 3.1.1.1.1 Hardware Modifications forWater Meter Operation in MSP430FR6043 Optimized Ultrasonic Sensing Metrology Reference Design for Water Flow Measurement

If that's not it there are a couple things you might try:

Can you place the transducers directly across from one another in a bowl of water to get a good signal? If you can't get a good signal doing this then there must be something wrong with the signal chain. Double check all the connections, try different transducers, etc.
What is the resonant frequency of the transducers? Is the EVM set to use the same frequency?

Regards,

Evan

0 Megha Shah over 2 years ago in reply to Evan Lew

Prodigy 20 points

Hi Evan,

Thank you for your response! I have already modified the board for water configuration. These are 2MHz transducers, and I have already set the parameters on GUI based on the transducers- as suggested in the guide.

My next step was to try them in a bowl of water, so I will update you once I get the results.

0 Evan Lew over 2 years ago in reply to Megha Shah

TI__Genius 10010 points

Ok, glad to hear you made the updates for water measurement.

When testing in a bowl of water, make sure the transducers are directly across from one another.

I'm interested to hear your findings.

Regards,

Evan

0 Megha Shah over 2 years ago in reply to Evan Lew

Prodigy 20 points

Hi Evan,

I tested the transducers in a water container, but the expected result is still not achieved (see image). I am using "AUDIOWELL Ultrasonic Flow Transducer/ 2MHZ for ultrasonic Water Meter" for the experiment. Let me know what you think.

0 Evan Lew over 2 years ago in reply to Megha Shah

TI__Genius 10010 points

Ok, thanks for trying that experiment. Can you probe the transducer signal lines with a scope while performing this experiment. You can see this post as a reference for what you should see:

https://e2e.ti.com/support/microcontrollers/msp-low-power-microcontrollers-group/msp430/f/msp-low-power-microcontroller-forum/1127126/evm430-fr6047-adc-capture-shifted-amplitude/4195839#4195839

Regards,

Evan

0 Megha Shah over 2 years ago in reply to Evan Lew

Prodigy 20 points

Hi Evan,

As shown in the image below, it seems to transmit the signal fine but has trouble receiving it. The picture of setup is also included below- let me know if something is off.

+1 Megha Shah over 2 years ago in reply to Evan Lew

Prodigy 20 points

I got it working!

0 Evan Lew over 2 years ago in reply to Megha Shah

TI__Genius 10010 points

Hi Megha,

That's great! Would you be able to post a quick summary of the problem and how you solved it?

Regards,

Evan

0 Megha Shah over 2 years ago in reply to Evan Lew

Prodigy 20 points

I am not exactly sure what fixed it- I resubmerged the transducers in the 3d printed vessel in the water container and played around with frequency sweep. When I reran the ADC capture, it got better. It seems like a combination of transducer alignment and performing a frequency sweep allowed the transducers to communicate better. Not sure if you have seen this happen before.

Thanks for all the help!

0 Evan Lew over 2 years ago in reply to Megha Shah

TI__Genius 10010 points

Great to hear. I only asked it because it helps me to understand for future reference. Alignment and mechanicals can have a big affect on signal propagation.

Regards,

Evan

**Attention** This is a public forum

MSP low-power microcontrollers

MSP low-power microcontroller forum

EVM430-FR6043: Incorrect ADC capture