[0:00] Hey everyone,
[0:01] I’ve been doing a lot of audio projects recently
[0:04] and for audio input I’ve settled on using I2S MEMS microphones
[0:09] These are great devices that you interface directly to
[0:13] your microcontroller without needing any analogue to digital conversion.
[0:18] The breakout board that I’ve mostly been using
[0:21] has been based around the INMP441 microphone
[0:25] and although there seem to be plenty of these boards available
[0:28] the actual microphone is no longer manufactured
[0:31] and is not recommended for new designs
[0:34] it’s also quite old now and it’s two generations behind.
[0:38] The latest microphone from InvenSense is the ICS-43434
[0:45] There are a couple of boards available from the US but the shipping costs are quite high.
[0:51] So, I’ve decided to get a few boards manufactured for myself.
[0:56] I’ve got a few of these boards available on eBay and Tindie
[0:59] and the schematics and pcb files are also available
[1:02] Links are in the description feel free to use the designs
[1:05] and have your own boards manufactured
[1:08] if you do get the boards from me then
[1:10] you’ll need to solder on the header pins
[1:13] I find the best way to solder these kinds of boards is to put the header into a breadboard
[1:19] along with some supporting pins to keep the board aligned
[1:32] I also apply a small amount of flux to help the soldering process
[1:50] Wiring up the boards is very straightforward
[1:53] we need 3.3 volts and ground these boards are not 5 volt tolerant so
[1:59] do not connect them to the 5-volt rail or you will damage them
[2:02] we also need the word select clock (also known as the LRCLK)
[2:08] we need the serial data and we need the serial clock
[2:12] I’ve shown the equivalent setup for the esp32 in the box for this wiring setup.
[2:19] sample code for this is also in the GitHub link in the description
[2:24] let’s have a listen to some of the audio
[2:29] testing testing one two three
[2:33] so quality seems really good and it’s very low noise
[2:38] now for those of you interested in looking under the hood
[2:41] I’ve also recorded the pcb design process
[2:45] now the actual circuit is pretty simple
[2:48] we need a connector and obviously, we need the actual microphone
[2:53] there’s a decoupling capacitor between VDD and GND
[2:57] and there’s a pull-down resistor on the serial data line
[3:01] that’s all you need circuit wise
[3:03] laying out the PCB is pretty straightforward
[3:05] the only slightly tricky part
[3:08] is routing the VDD line
[3:10] I wanted to keep GND and VDD together to keep it logical
[3:14] which means i need to route the VDD slightly around the houses
[3:18] I also want to keep all the traces on one side of the board
[3:23] so with all the traces routed
[3:26] we can add the board layout and add a couple of screw holes
[3:30] we’ll also add a ground pour to both sides of the board
[3:33] and a couple of vias to link the sides together
[3:36] now with the layout completed
[3:38] we just need to add some nice labeling
[3:40] the microphone is bottom ported
[3:42] so all the labels will be on the bottom side of the board
[3:45] which from a user’s point of view will be the top side of the board
[3:49] with that done we just export the Gerber BOM and pick and place files and send
[3:53] it off to PCBWay for manufacture and assembly
[3:57] PCBWay dealt with all the panelling and component sourcing
[4:01] and within a few weeks a box has arrived
[4:04] It’s all nicely packaged up in individual anti-static bags,
[4:08] they’ve even given me the leftover components
[4:10] so I’ve got a bunch of capacitors and resistors
[4:14] and there’s one leftover microphone
[4:16] if anyone fancies trying to solder this they are more than welcome to it!
[4:21] Thanks for watching
[4:22] hope you enjoyed this video
[4:24] I’m still working on another big project and I hope to finish it soon