How to get rid of audio spike of MP34DT06JTR in STEVAL-BCNKT01V1. and and the frequency response does not follow the specification. + Power issue

[TOuyp.1]

Hi,

I am working with STEVAL-BCNKT01V1 (Bluecoin board) with the sample project FP-SNS-ALLMEMS1 and BlueMS for android (with default configuration.) I found that there are many spikes in the mic signal occurring every 20-70ms. To make sure the hardware working well, I ordered another one, but the result was the same. Does anyone have the problem similar to me and how to fix this problem?

Further more, since I have to work with low frequency under 150Hz, which the datasheet of MP34DT06JTR  says it should work well to 100Hz (very small different to the frequency of 1kHz). (Actually, I need down to 50Hz.) However, I barely detected the signal under 200Hz. I tried to test with pure sine wave sound of under 500Hz. At 500Hz, it worked perfectly. At 200Hz, significant distorted waveform was detected. And I could not detect at all at 140Hz. Could anyone confirm the performance under specification of MP34DT06JTR ?

I also found that, frequently, I could not turn on the Bluecoin board (with/without battery). The power LED blinked for a half second and shut itself. Sometime, the four LEDs blinks for a time and then shut itself down again. Do you have any suggestion regarding this problem?

PS. It seems IC chips from ST are shortage, My project schedule is now ruined due to the lack of ICs (ARM) in the market. Do you know when I can make an order again? The suppliers say I have to wait for a year!!

Best regards,

Taweechai

[Eleon BORLINI]

Hi Taweechai @TOuyp.1​ ,

while waiting for internal support, let me comment a bit the question more related to the microphone device.

I can say you that the MP34DT06JTR frequency response itself is basically flat in all the audio bandwidth, so you should be able to acquire well all the frequencies between 20Hz and 20kHz. I would say that you have disturbances every 20-70ms (say "glitches"), the frequency below 1/20ms=50Hz will be distorted, so confounding the signal into high noise.

About the STEVAL-BCNKT01V1, please note that the BlueMS application is now replaced by the STBLE Sensor, so that I would first check this point. Note also that the preloaded firmware on BlueCoin Kit is the FP-AUD-SMARTMIC1: could you try uploading this example?

>> PS. It seems IC chips from ST are shortage, My project schedule is now ruined due to the lack of ICs (ARM) in the market. Do you know when I can make an order again? The suppliers say I have to wait for a year!!

That's a tricky point, for sure... I suggest you to open a case in the OLS at this link, they will be able to explain this point better than me for sure.

Keep me please updated in case you are able to make the kit working.

-Eleon

[TOuyp.1]

Hi Eleon,

Hi, I would like to update in accordance with your reply (sorry for late, I just see your reply). I have tried to use FP-AUD-SMARTMIC1, and a good news - the glitches were disappeared WHEN the recording performed on PC (as a new sound recording device.) HOWEVER, the sound came out from the audio jack of Bluecoin station was very noisy (but not glitch). This may be sure that the glitched were not due to the hardware of bluecoin (STEVAL-BCNCS01V1) itself, but may be due to firmware AND/OR due to the bluecoin android application. I also have tried with en.fp-sns-allmems2 (the latest one), but the glitches still presented as same as using en.fp-sns-allmems1. This is unfortunate for me, because I need to capture sound with BLE. I don't know how difficult to merge these projects together (and hope ST will fix the problem for the example project of using BLE). FP-AUD-SMARTMIC1 project also is not designed for using with BLE.

A bad news is when using en.fp-sns-allmems2, the bluevoice feature (bluevoice fragment) becomes mess. I tested with the latest ST Blue Sensor app (downloaded from PlayStore). In the bluevoice activity of the app, I have to slide the option of beamforming on and off first before it can be functional. Furthermore, when I program bluecoin with this en.fp-sns-allmems2 version, and use with my android application modified from BlueMS-Android (https://www.st.com/en/embedded-software/bluems.html#overview) which worked well with en.fp-sns-allmems1, the bluecoin communication becomes halt on this version. I then cannot upgrade to the new version of en.fp-sns-allmems.

Could I ask you more question please? I would like to know can I capture both voice data and MEMS data e.g. temperature in the same time (do not need to logging or recording). I modified BlueMS-Android project, and I found that voice data and MEMS data can be acquired in the same time but for only about 5-15 seconds, and then the connection is dead (status=8). This is quite surprise because the sampling rate of temperature data is just 2Hz. May be there are something I do not know and you may be able to help me.

Regarding the frequency response, I have retried the test (because I am not sure the performance of the speaker I used.) And that it! I can detect the signal at the frequency below tp 60Hz. But the amplitude was 5-10 times smaller than that at 500Hz. However, the waveform started to distort at 200Hz. This is quite surprise me because some speaker cannot generate low frequencies and some will change the frequency!, I generated 100Hz sound from my mobile phone and bluecoin found 300Hz sound instead. But at 200Hz, everything worked well (with some distorted.)

Regarding the IC shortage question, I have asked the ST onlinesupport, and they suggested me to post here (in the community) and they have closed my case now. Kinda disappoint.

There are many agenda above. These are my summary.

1. How I can know the glitches come from firmware (en.fp-sns-allmems) or android app (BlueMS-Android) and any suggestion to fix
2. Is there bug in en.fp-sns-allmems version2 ? I don't know precisely which codes were updated. This causes to me to not update the firmware.
3. Can I capture voice data and MEMS data in the same time?
4. (If possible to find an answer) What is happening to ST regarding the IC shortage?

Regards,

Taweechai