SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
In manual mode (the PLL_CONTROL[0] PLL_AUTOMODE bit is set to 0), the DPLL requires a sequence on TINITZ, TENABLE, and TENABLEDIV to update the configuration values and start the locking sequence.
When all the configuration values are programmed into the registers, the GO bit must be set. The appropriate sequence is then sent on the TINITZ, TENABLE, and TENABLEDIV pins, respecting the timing requirements of the DPLL. The PLL_GO[0] PLL_GO bit is cleared to 0 at the end of the sequence.
The TENABLEDIV signal is shared with the HSDIVIDER module so that it is programmed at the same time. In this mode, software must deassert CLKINEN by setting the PLL_CONFIGURATION2[14] PHY_CLKINEN bit to 0 and assert HSDIVBYPASS correctly by setting the PLL_CONFIGURATION2[20] HSDIVBYPASS bit to 1 to prevent uncontrolled frequencies affecting the display subsystem or the other modules using DPLL_VIDEO during PLL locking. In manual mode, the shadow register is updated anyway so that valid values are present when later selecting automatic mode.
Figure 11-14 shows the VIDEOx PLL Go flow chart in manual mode (the PLL_CONTROL[0] PLL_AUTOMODE bit is set to 0).
In automatic mode (the PLL_CONTROL[0] PLL_AUTOMODE bit is set to 1), the TINITZ, TENABLE, and TENABLEDIV sequence and the update of the PLL configuration from the PLL_CONFIGURATION2 register are deferred until the time of the front porch time signal sent by the DISPC module. This is intended to simplify the software to implement a configuration change (such as a frequency change to support a different link bandwidth). In this mode, CLKINEN, HSDIVBYPASS, and REFEN are automatically controlled and the register value is overridden.
Figure 11-15 shows the VIDEO PLL Go flow chart in automatic mode (the PLL_CONTROL[0] PLL_AUTOMODE bit is set to 1).