a picture of the hardware. I mounted the AVR Butterfly board and
a socket for the DDS on a proto board. The DDS-60 is installed
vertically above the Butterfly.
the lower right of the Butterfly is a 4-pin connector for the rotary
encoder. It is wired to J402, which is the second connector from
the left below the LCD. The mechanical encoder just needs three pins
(A, B and GND), while the optical encoder adds +5 VDC to power the
optical sensors. In the front with the black knob is a mechanical
encoder temporarily wire-wrapped to the board for testing.
of the proto board is my homebrewed optical encoder. The wheel
and sensor came from a bathroom scales. Note that the bushings
for the 1/4 inch shaft were made from 1/4 inch phone jacks.
optical encoder has the advantage of more steps per turn. Also,
the mechanical encoder has detents and moves with a click for each
step. Not exactly a good choice for an "analog feel" knob.
But really it does pretty well for general usage and it's
obviously much more compact.