I need to vary the frequency of operation of a transceiver IC from
7MHz to 9MHz. The oscillator needs to feed into the crystal
oscillator input and crystal oscillator output pins of the IC (the
current design does not have a variable oscillator and is just using a
crystal). Ideally I would like to control the frequency of the
oscillator using the PWM of a micro controller (unfortunately the
current micro does not have a DAC). Any ideas on the best way to do
this?