The reference frequency in this circuit drives the input of an exclusive-OR gate (XOR gate U2) as well as the input to a delay circuit. Consisting of R1, C1, and comparator U1, the delay circuit ...

[David Johnson-Davies] recently built a proof of concept using the Configurable Custom Logic (CCL ... to form the frequency divider. Think of these like a NAND or XOR gate, but you get to decide ...