SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
Once all the configuration values have been initially programmed into the DPLLCTRL_USB_OTG_SS registers (see Section 26.2.4.3.7.3) , the DPLLCTRL_USB_OTG_SS.PLL_GO[0] PLL_GO bit should be set to update the configuration values and start the DPLL calibration and locking sequence.
After the DPLLCTRL_USB_OTG_SS.PLL_GO[0] PLL_GO bit is set high in software, the DPLLCTRL_USB_OTG_SS state-machine takes the following action:
Figure 26-13 summarizes the software and hardware sequences flow of DPLL_USB_OTG_SS.
All thick-outlined blocks show operations performed by software. Other blocks show operations performed by hardware.
DPLL_USB_OTG_SS relock sequence:
When the 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 the DPLLCTRL_USB_OTG_SS.PLL_GO[0] PLL_GO bit to 0b1 for DPLL parameters update.
When DPLL_USB_OTG_SS enters a relock sequence, CLKDCOLDO is pulled low. FREQLOCK and PHASELOCK status signals are also low. CLKDCOLDO output clock is activated after the FREQLOCK or PHASELOCK signal goes high, depending on the selected locking criteria.
The DPLLCTRL_USB_OTG_SS.PLL_GOUSB3PHY_PLL_GO[0] PLL_GO bit can be used by software to monitor if DPLLCTRL locking process is still pending (PLL_GO = 0b1).