Microcontrollers usually do not include D/A converters but you can easily create a crude version of one usually signle digital I/O pin. This can be done by outputting a variable-width pulse train to an RC circuit. Write a PicBasic Pro subroutine that uses pin RA0 to output a constant voltage of between 0 and 5V that is proportional to the value of a byte variable called digital_value, whose value can range from 0 to 255. The subroutine should hold this voltage for approx. 1 sec.