SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
Once all the configuration values have been initially programmed into the DPLLCTRL_SATA registers (see Section 28.1.4.3.7.2, SATA DPLL Clock Programming Sequence), the DPLLCTRL_SATA.PLL_GO[0] PLL_GO bit should be set to update the configuration values and start the DPLL calibration and locking sequence.
After DPLLCTRL_SATA.PLL_GO[0] PLL_GO bit is set high in software, the DPLLCTRL_SATA state-machine takes the following action:
Figure 28-6 summarizes the software and hardware sequences flow of DPLL_SATA.
DPLL_SATA Relock Sequence: When DPLL leaves a lost clock condition (LOSSREF = 1 → 0) or idle-bypass mode it enters relock sequence from the first CLKINP edge (after bypass mode leaving). Relock sequence is the same as calibration-lock sequence already described.
A DPLL relock sequence is also software triggered by setting DPLLCTRL_SATA.PLL_GO[0] PLL_GO bit to 0b1 for DPLL parameters update.
When DPLL_SATA enters a relock sequence, CLKDCOLDO is pulled low. FREQLOCK and PHASELOCK status signals are also low. CLKDCOLDO output clock is activated after FREQLOCK or PHASELOCK signal goes high, depending on the selected locking criteria.
The DPLLCTRL_SATA.PLL_GO[0] PLL_GO bit can be used by software to monitor if PLLCTRL locking process is still pending (PLL_GO = 0b1).