Music module and microphone

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.


Also, I just looked at the specs and the chip says it has an on-board microphone amplifier.


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


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.

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?


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

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.


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?


Bit 14:
MIC / LINE1 selector

if I modify line code

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


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

when SM_MICP = 0

you turn on the mic amplifier?


not sure of the correct values, it will be in the datasheet: