Music module and microphone

Archive
1

Just got an email asking how to use the music module to record sound from a microphone. The page for the music module says the input is a “regular audio” jack. Does this mean it’s line level and will need a preamp to boost it?

The reference page shows how to record input, so I assume it’s a line/mic level issue.

Also, the page incorrectly refers to the jacks as RCA. Those look like normal 3.5mm TS connectors, not RCA jacks.

Pete

2

Also, I just looked at the specs and the chip says it has an on-board microphone amplifier.
http://www.vlsi.fi/en/products/vs1053.html

Pete

3

Thanks, but that would be opposite of the product info on the site here:

https://www.ghielectronics.com/catalog/product/317
“Important Note: The RCA connector marked “MIC” does not work with microphones. It is a regular Audio in connector.”

(also, it’s not an RCA connector)

Pete

4

IIRC, it is a line in but with some few components it can be mic input. Compare the schematics to the one found in the VLSI datasheet please.

5

Thanks Gus

If it’s line in, the simplest (but by far not the cheapest) approach for this person would be to add a cheap pre-amp.

Also, can you have the description updated so it doesn’t call them RCA jacks?

Pete

6

the input is selectable between MIC vs line level. If you look at our driver it appears that our record function sets it LINE

7

Just compared schematics (thanks for posting these, guys. I love that your schematics are online).

I see a jumper for mic input, without any of the other circuitry for mic input (looks like it needs a number of caps to support microphone input).

I also see that line input is stereo, which I didn’t realize. All good there.

Here’s a really inexpensive pre-amp kit which may fit the bill.
https://www.sparkfun.com/products/8872

Pete

8

Thank you guys for the informations. (I’m the one who contacted Pete)

I have another question:
In the modules source code I saw that first you set the volume to 255, 255. I assume this means you set the volume on both channels to the max. As far as I can see this also affects the volume of the output. Is this true?

And is it even possible to play a file and record to another file at the same time with one single Music Module?

9

Hi,

Bit 14:
SM_LINE1:
MIC / LINE1 selector
0 MICP
1 LINE1

if I modify line code

CommandWrite(SCI_MODE, (ushort)(CommandRead(SCI_MODE) | SM_ADPCM | SM_LINE1));

with

CommandWrite(SCI_MODE, (ushort)(CommandRead(SCI_MODE) | SM_ADPCM | SM_MICP));

when SM_MICP = 0

you turn on the mic amplifier?

Thanks
Luca

10

not sure of the correct values, it will be in the datasheet: http://www.vlsi.fi/fileadmin/datasheets/vlsi/vs1053.pdf