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 oscillator
- Low frequency digital
input – WKUP_LF_CLKIN - Low Frequency 32k digital clock input,
optionally sourced from an external PMIC or other clock source. This SoC
does not support a LFOSC crystal 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).
- External video pixel clock inputs
- VOUT0_EXTPCLKIN — optional for the DPI0 port of DSS.
- 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.
- External audio reference clock input/output pins.
For more information which clocks may be sourced as an outputs to the pins, see
Section 12.5.2,
Multichannel Audio Serial Port (MCASP).
- AUDIO_EXT_REFCLK0
- AUDIO_EXT_REFCLK1
Note: Other clock inputs that are routed directly to the subsystems are described in the respective subsystem chapters.