Crystal 32.768K

A 32.768 kHz quartz crystal, providing a far more accurate and stable clock reference than a microcontroller's internal RC oscillator. This is the watch crystal frequency, and the number is not arbitrary: 32768 is 2 to the power of 15, so a simple 15-stage binary divider produces exactly one pulse per second. That is why it is the standard reference in every real-time clock and wristwatch. A crystal needs two small load capacitors to ground, typically 18-22 pF, to oscillate correctly - without them the circuit may not start or may run at the wrong frequency. Keep the tracks between crystal and microcontroller as short as possible. Far more accurate and stable than an internal RC oscillator; Essential for reliable serial communication timing; Low cost and extremely reliable; Standard through-hole package fits breadboards