MC9S12C32 - Interfacing a microphone, speaker, and more memory

[phaze]

Hello all,

First, thanks for reading.  Let me share some background info.  I am in my last semester of engineering at my university and my team (4 guys) is building a robot for an internal competition (local to the university). 

We plan to use the NanoCore12 NC12DXC32 which uses the 9S12C32.  Our design will have 3 IR sensors, 2 distance sensors, 6 LED's, a 8x2 char LCD display, and we want to have a speaker and microphone.  (The robot most likely won't be moving when a person is using the microphone feature)

I wanted to know if anyone here has experience using/interfacing a microphone (I am guessing it will use an input capture port) with this mcu, and if we would need additional memory to actually make the feature "worth it".

This is based on my estimation that 1 second of audio at 500 hz will take up almost all of our ram (2k).  It would be nice to record 4 seconds or something and to store it in memory so that some filtering could be done on the data (maybe filter out the lower or higher frequencies, and play it back on the speaker).  

What is the most common way to add memory?  A 4k chip?  Luckily, two of our team members have experience with the motors, chassis, h bridge, and distance sensors.  We just need some guidance on memory expansion, mic and speaker.  

Thanks in advance and I would appreciate any feedback or suggestions.  If you need more info from my side I would be happy to share.

Thanks

[WadeH]

The Nanocore module doesn't have enough pins to add an external parallel memory, but you could use an SPI or IIC serial memory chip. There is a bigger Nanocore (NC12MAXC128) that has 128K of flash, if your sound info doesn't have to change on the fly.

Inputting sound from a microphone would seem to be best done by using an A-D converter input. A 4-6KHz

sample-time with 10-bit resolution should give intelligible sound.

A single-bit input could aslso be used, with some additional programming trickery: see the link below

     http://www.romanblack.com/BTc_alg.htm

You have some engineering to do: have fun!

Wade Hassler