08/23/2018 at 10:56 •
Im happy with the TSC peripheral on the STM32 and capacitive sensing as the sensing method.
I have begun capturing a schematic and doing rough placement of the components for the pcb layout.
I'm using the STM324042C6T6 as my MCU
I have gotten all the individual parts of the software working on the STM32: USB HID and TSC Touch sensing. I have a working prototype but the code is really ugly at the moment so Ill clean that up once the schematic and PCB is done, and i've decided on the pin mapping.
I've never done routing for Cap touch so I need to read into that a bit. I've added 6 electrodes on the board for a few reasons one being to have a board with 6 different cap touch inputs on to test the peripheral, another is to see what other mouth movements I can detect, i though licking left to right might be interesting / funny, but either way it give me some elbow room to play a bit. The 'look' of the board is not complete, i would like the PCB to be the package of the device so I still need to give that some thought.
Still to do:
Clean up code and publish a working version thus far
Finish schematic and publish
settling on look and feel of the pcb
look into an enclosure, if its something I want / need and what that might look like
Work on final firmware, and eventually publish
Below is a screen grab of the rough component placement on the PCB without any though on overall finish and aesthetics
08/23/2018 at 10:22 •
I wanted to try using capacitive touch as the sensing method for two reasons, one to allow me to sense kiss/touch without direct contact with the electrode, and to try out the TSC peripheral on the STM32 MCU's.
I previously built a MakeyMakey re implementation based on the STM32, so using that board I did some basic rework to add a sampling capacitor to the pcb so I could use the existing electrodes as capacitive touch electrodes and test out the MCU's capabilities. I added a piece of perspex to isolate the electrodes from my finger and attached two APA102's to the board that light up when I get close to the electrodes with my finger
Below is a video of the device in use
08/23/2018 at 10:01 •
I made a second version of the device to test a different sensing method. This version used high resistance switching to detect kissing. To quickly test this method out I cut a piece of copper clad board the same dimensions as the MakeyMakey, drilled some hole and etched a quick set of lips to act as the ground and input electrodes.
Using brass standoffs I connected the bottom lip to the ground bar of the pcb and the top lop to the 'up-arrow' input on the board. I edited the code and quickly got a working version up and running.
After testing with the board for a while I realized the idea of kissing copper might not be that attractive to most. So my next test will be using capacitive touch sensing to allow me to detect touch/kisses without direct contact on the electrodes.
08/23/2018 at 09:52 •
The first version of the device was a transistor and some copper tape connected to an Arduino Pro Micro.
It was really crude but got the job done, below is an image of the device and schematic diagram
I was using a BC547 NPN Transistor. The 100k resistor is a stand in for my lips which bridged the collector with the base which pulled the logic line connected to Arduino LOW. This then send the emoji key presses over USB to my computer
The prototype had the 5v line and Transistor Base connected to 2 separate strips of copper tape that were connected via your lips when ever you kissed it.