SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
When running in normal locked mode, the PHY DLL gets a reference clock (EMIFi_DLL_FCLK) from the PRCM, which is used by the DLL master to lock to the right frequency and provide the control code for a full period phase shift to the slave. The slave uses this code as a control for its internal delay line to produce the required delay for the signal considered.
When working in locked mode, the delay lines only get an updated control value from the master DLLs when an explicit dll_calib command is issued by the EMIF controller. Failure to send such commands on a timely basis will result in inaccurate delay-line information if there is a significant voltage and temperature drift in the system. It is recommended to issue at least one command every 100 µs. EMIF automatically sends ctrl_update commands for:
The PHY also internally generates a control value update upon completion of a leveling operation. Control is also added when leveling is not used and there are gradual voltage changes during frequency change. The EMIF_DLL_CALIB_CTRL register can be programmed to generate a phy_dll_calib for a periodic interval based on EMIF_FICLK cycles, so allow continued memory access as voltage is changing. A safe window of no activity will be guaranteed for this periodic generation of phy_dll_calib. In addition, a one shot generator for phy_pll_calib has also been added that will generate a single phy_dll_calib by setting the EMIF_MISC_REG[0] DLL_CALIB_OS bit to 1.