Instruct the compiler to override the crystal frequency options setting.
$CRYSTAL = var
Frequency of the crystal.
var : Constant.
When you want to use an unsupported crystal/baud rate you can use this compiler directive.
When you do, you must also use the corresponding $BAUD directive.
These statements always work together.
$baud = 2400
$crystal = 14000000 ' 14 MHz crystal