we're limited by the itm busrate. but we can at least get a cleaner
signal by sampling at a higher rate and then downsampling before sending
to the PC.
I can see very clear signal when I:
- tape only the contacts of the sensor to the table, and
- bend the free end into the air, and release (it snaps down)
I think I need an op-amp for the piezo element. It seems like just
running 6" wires to it causes too much noise in the wires to be able to
detect the piezo element. Need an amplifier right next to the piezo
before sending it over any wire.
With 0b000 sample time, reading values of 0xd0 +/- 20
With 0b111 sample time, sometimes I read all the way between 0x000 and
0xfff. But it's not random noise -- it's oscillating like a sine wave at
maybe 1 hz. The noise is there when I connect long wires to the ADC
pins, but regardless of what's on the other end of the wire (piezo or no
piezo).
Could also be worth trying differential mode.
colin