Sparkfun ESP32 thingplus

[Andrew Nolan]

Hi, I was looking at this board which has the ESP chip, SD card reader, lipo charger,  qwiic 12c connector, and importantly for me, available touch pins. Could your code be ported over to use the SD interface rather than the onboard eMMC?

[WVR Audio]

Yes in could be done, I don't know how easy it would be to port the WVR code, but it should be possible.

You will lose a lot of the polyphony, and the latency will be a bit higher, because the SD is slower.

[WVR Audio]

It may be easier to add a cap touch IC to WVR. They are very cheap.

[Andrew Nolan]

I was having a look at the cap sense functions on the esp32 and it seems they are buggy, not to mention the extra code needed to define the cut points for the sensors and then weed out the false positive responses etc etc. You are right, its much easier to use a dedicated cap sense IC that does all that out of the box, like the MPR121. Thanks for all your work on the CC pitchbend, I have yet to try it out as I am on vacation. 

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[WVR Audio]

Yes, I have found the touch sense to be a little buggy at times. What I get is cross-talk. It is hard to tell if the issue is the ESP32 or my own touch pad design, it is a fairly involved science apparently. I seem to recall that the WiFi also confuses the internal cap sense, which wouldn't be the case with an external IC.

I have another project which uses an external IC for cap sense and it is a lot more reliable, but the tradeoff is that you don't get interrupts as easily, so you would need to poll the cap sense IC quite fast to avoid latency, or research an IC that provides interrupt-on-change if there is one.

[Andrew Nolan]

I have tried the sparkfun Qwiic mpr121 board and found it reliable, although it’s a bit too big for my flute project. I also ordered a seeed module which is a bit smaller and can be trimmed even thinner. The advantage of the mpr121 is that you get a different number returned for each fingering combination in the case of a wind controller instrument which is easy to map to midi notes. I use antenna coax with the shield stripped off to maintain distance between conductors, also keep the I2C line right away touch conductors. 

On 25 Sep 2023, at 7:30 am, WVR Audio <wvr-...@googlegroups.com> wrote:

Yes, I have found the touch sense to be a little buggy at times. What I get is cross-talk. It is hard to tell if the issue is the ESP32 or my own touch pad design, it is a fairly involved science apparently. I seem to recall that the WiFi also confuses the internal cap sense, which wouldn't be the case with an external IC.

To view this discussion on the web visit https://groups.google.com/d/msgid/wvr-audio/5a2a4254-3deb-41f4-a84e-234c622c9e9dn%40googlegroups.com.

[WVR Audio]

Just FYI you get a single number from ESP32 as well. Different libraries will abstract that away, I get the raw number and then do some tricks on it to get it to work the way I want for WVR buttons here https://github.com/marchingband/wvr/blob/07f6e319ef77eee66a62b7d5ac01700bf71d40e8/src/button.cpp#L34 but you could instead map it to notes.