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vs1053:recording from LiNE1:weak signal

Posted: Sat 2021-12-04 19:10
by zulunation
Hi All,
I am using vs1053b. It works fine when playing the music and recording from electret microphone.
I am trying to record from LINE1.
I have a piezo module with it's own amplifier (LM386). When I connect headphones to my module I hear that signal is very good.
Then I connect output of my module to the LINE1 of vs1053b.
The LINE1 is connected like on schematics. I goes through 470ohm resistor and 1uF capacitor and then to my module.
Also LINE1 is connected to ground through 10nF capacitor.

Here is my configuration code:

Code: Select all

record_gain = 1024;
sample_rate = 8000;
max_autogain = 1024;
stereo_mic = 0x06;
I do not modify the SCI_VOL register. So it has maximum volume.

When i record the signal level is very low.
I check that with headphones connected to the LEFT/RIGHT output of VS1053.
When recording vs1053 redirects signal from LIINE1 to LEFT/RIGHT. SO i can hear the live signal.
Also i see that sensitivity is low on wav file.
When recording i can connect headphones in parallel with vs1053 and my module an i hear the good sensitive signal.

What else should i check?

Re: vs1053:recording from LiNE1:weak signal

Posted: Tue 2021-12-07 15:12
by pasi
Do you have an oscilloscope to determine what is the actual signal level at the LINE1 pin? What is the resulting level in the WAV file?

You're writing 0x5004 to SCI_MODE (LINE1 + ENCODE + SOFTRESET). Are you intentionally using the SDI compatibility mode and not NEWMODE?

Have you tried with the vs1053b patches package or with the small patch provided in the vs1053 datasheet?