Fractional divider for RF (SCT is awsome!)

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by MarcVonWindscooting on Thu May 01 12:53:43 MST 2014
Today I wrote a program that does something I wanted a long time ago: the possibility to precisely control the switching frequency of a half bridge driver for exciting a tank circuit well above 1MHz.
Using PCLK and dividing does not yield the required accuracy, because the divider is a small number only. Therefore I used the SCT (split in two) to generate a simple PWM and then use that PWM's output to switch between two fixed frequencies (close to each other) of the other part of the SCT.
The whole logic runs from the SCT alone, no ISR, no software action required!
SCT is so awesome  8-)

Of course, the approach has some flaws and the values have to be chosen carefully, but LPC800 + SCT makes things possible that weren't feasible with a 100MHz LPC1700!

Original Attachment has been moved to: sct.c.zip