On Thu, 11 Sep 2003 08:34:20 +1000, you wrote:

>Has anyone seen published a circuit and PIC program that achieves =
something
>similar to what is described below?
>
>There need to be two 0-9 BCD rotary switches, one representing 1 Hz per
>detent and the other 0.1Hz. These cause a PIC micro (8 pin?) to output a
>50% duty cycle squarewave at the selected frequency. For example, a 6 =
and 3
>would result in 6.3Hz.
>
>The PIC's output is then fed to a 16 bit shift register with resistors
>weighted according to sine function, or any other waveform required. =
This
>output is to drive a 500R solenoid via a rail-to-rail (single supply) OP
>amp. Power consumption is a key factor, as the circuit will run from a =
9V
>battery.
At these low frequencies, you could probably do away with the shiftreg =
and output a PWM or
pulse-density modulated signal from the PIC, with a simple filter to get =
the analogue output.=20

You'll need more than 8 pins to read the switches - (OK it may be =
possible on a '675 using the ADC
but will be a bit of a pain) - an 18 pin device will be a lot easier!

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