1.6 KiB
I did some performance testing.
The Pro Micro runs an Atmel 32u4 at 8MHz. If the code does nothing else, I was able to poll all pins around 13 times every 1ms, or 13kHz.
Sample Rate
The number of samples taken since the last HID report is sent as the second Y axis. If you use the included gamepad tester, it will show the approximate number of samples as an integer, for Y axis 2.
This is approximate, because the browser encodes the value as a real number between -1 and 1. We convert it back, but may lose a little precision. It's close enough for me, hopefully it's close enough for you.
Debouncing
Using millis() time to debounce the switch
roughly halved my sample frequency.
So instead, I do some preprocessor arithmetic
to calculate how many samples to take after an edge,
in order to debounce switches.
The drum controller was a partcular pain: in addition to the switch bouncing, the stick was bouncing on the rubber pad. I settled on a 40ms silence window as feeling pretty good. You can adjust this if you want to.
Gamepad Buttons
The buttons struct member is a bitmap,
each bit mapping to one of the 12 buttons reported through HID.
Here's what each bit means:
- 0: Blue
- 1: Green
- 2: Red
- 3: Yellow
- 4: Orange
- 5: Tilt Switch / 2x kick
- 6: Solo modifier (second row of buttons on guitar)
- 7: ?
- 8: Minus
- 9: Plus
- 10: Drum pad modifier?
- 11: Cymbal modifier?
- 12: ?
hatAndConstant
I don't get this, but here's what the values mean:
- 2: right
- 6: left
- 0: up
- 4: down
- 8: nothing