Hey everyone,
I've been doing a lot of audio projects recently
and for audio input I've settled on using I2S MEMS microphones
These are great devices that you interface directly to
your microcontroller without needing any analogue to digital conversion.
The breakout board that I've mostly been using
has been based around the INMP441 microphone
and although there seem to be plenty of these boards available
the actual microphone is no longer manufactured
and is not recommended for new designs
it's also quite old now and it's two generations behind.
The latest microphone from InvenSense is the ICS-43434
There are a couple of boards available from the US but the shipping costs are quite high.
So, I've decided to get a few boards manufactured for myself.
I've got a few of these boards available on eBay and Tindie
and the schematics and pcb files are also available
Links are in the description feel free to use the designs
and have your own boards manufactured
if you do get the boards from me then
you'll need to solder on the header pins
I find the best way to solder these kinds of boards is to put the header into a breadboard
along with some supporting pins to keep the board aligned
I also apply a small amount of flux to help the soldering process
Wiring up the boards is very straightforward
we need 3.3 volts and ground these boards are not 5 volt tolerant so
do not connect them to the 5-volt rail or you will damage them
we also need the word select clock (also known as the LRCLK)
we need the serial data and we need the serial clock
I've shown the equivalent setup for the esp32 in the box for this wiring setup.
sample code for this is also in the GitHub link in the description
let's have a listen to some of the audio
testing testing one two three
so quality seems really good and it's very low noise
now for those of you interested in looking under the hood
I've also recorded the pcb design process
now the actual circuit is pretty simple
we need a connector and obviously, we need the actual microphone
there's a decoupling capacitor between VDD and GND
and there's a pull-down resistor on the serial data line
that's all you need circuit wise
laying out the PCB is pretty straightforward
the only slightly tricky part
is routing the VDD line
I wanted to keep GND and VDD together to keep it logical
which means i need to route the VDD slightly around the houses
I also want to keep all the traces on one side of the board
so with all the traces routed
we can add the board layout and add a couple of screw holes
we'll also add a ground pour to both sides of the board
and a couple of vias to link the sides together
now with the layout completed
we just need to add some nice labeling
the microphone is bottom ported
so all the labels will be on the bottom side of the board
which from a user's point of view will be the top side of the board
with that done we just export the Gerber BOM and pick and place files and send
it off to PCBWay for manufacture and assembly
PCBWay dealt with all the panelling and component sourcing
and within a few weeks a box has arrived
It's all nicely packaged up in individual anti-static bags,
they've even given me the leftover components
so I've got a bunch of capacitors and resistors
and there's one leftover microphone
if anyone fancies trying to solder this they are more than welcome to it!
Thanks for watching
hope you enjoyed this video
I'm still working on another big project and I hope to finish it soon