Cluck is a Common Lisp library to help automate clock and divisor selections for microcontrollers. Functions include: 1. show-timers Shows range of frequency and periods for 8 and 16-bit timers for a given clock frequency 2. ms-timer Shows prescaler, compare values, and percent errors for 8 and 16 times to acheive desired millisecond compare interrupts. 3. avr-uart-divisors / pic-uart-divisors Shows optimal divisors and percent error for common baud for serial communications 4. zero-error-uart-clocks Display common crystal frequencies that have zero uart timin errors for common serial communication rates