2.6 Clocks and Crystal Oscillators

The oscillator circuit must be placed on the same side of the board as the device. Also, place the oscillator circuit close to the respective oscillator pins, not exceeding one-half inch (12 mm) distance between them. The load capacitors should be placed next to the oscillator itself, on the same side of the board. Use a grounded copper pour around the oscillator circuit to isolate them from surrounding circuits. The grounded copper pour should be routed directly to the MCU ground. Do not run any signal traces or power traces inside the ground pour. If using a two-sided board, avoid any traces on the other side of the board where the crystal is placed.

Important: Crystal selection must be based on the crystal data sheet and the crystal oscillator parameters specified in the XOSC Electrical Specifications and XOSC32K Electrical Specifications within the Electrical Specifications chapter.
Note:
  1. It is recommended not to use any functions, such as UART, ISI, GPIO, or AFE that are mapped to PD30 when using XOSC32K.
  2. It is recommended not to toggle GPIOs, PA21, PA22, or PB03, when using XOSC32K.