Various external clock inputs are needed to drive the device. Summary of these input clock signals is given below. Some of those inputs are bidirectional and are marked as inputs/outputs in the summary:
- High frequency oscillators
- WKUP_OSC0_XO/WKUP_OSC0_XI — external main crystal interface pins of the internal oscillator which sources a reference clock. Provides reference clock to PLLs within WKUP/MCU and MAIN domain.
- OSC1_XO/OSC1_XI — external main crystal interface pins connected to internal oscillator which sources reference clock. Provides reference clock to PLLs within MAIN domain. This high-frequency oscillator is used to provide audio clock frequencies to MCASPs.
- Low frequency clock input
- WKUP_LF_CLKIN — External 32.768 kHz clock input.
- General purpose clock inputs
- MCU_EXT_REFCLK0 — optional external system clock input (MCU domain).
- EXT_REFCLK1— optional external system clock input (MAIN domain). Optionally PLL4 (AUDIO0 PLL) and MCASP can be sourced by EXT_REFCLK1 (sourced externally).
- External CPTS reference clock inputs
- MCU_CPTS0_RFT_CLK — CPTS reference clock inputs for MCU_CPTS_RFT_CLK.
- CPTS0_RFT_CLK — CPTS reference clock inputs for CPTS_RFT_CLK.
Note: Other clock inputs that are routed directly to the subsystems are described in the respective subsystem chapters.