SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
The Cortex-A15 MPU clock generator is fed by the MPU digital phase-locked loop (DPLL), which can be gated off by the global power, reset, and clock management (PRCM) module . There is a global clock gating for each MPU core. Because of the DPLL_MPU, the MPU subsystem is asynchronous from the rest of the device.
Figure 4-3 shows the MPU subsystem clocking scheme.
The clock generator generates the following clocks from the DPLL_MPU output clock (MPU_GCLK):
MPU_CORE_CLK is directly derived (no hardware dividing) from the DPLL_MPU output clock (that is, MPU_CORE_CLK = MPU_GCLK). The other clocks are derived via dividers.
Table 4-1 shows the supported frequency values for MPU subsystem clocks at different OPPs.
Clocks (Derived From DPLL_MPU) | OPP_LOW | OPP_NOM | OPP_OD | OPP_HIGH | OPP_PLUS |
---|---|---|---|---|---|
MPU_CORE_CLK (f) | See (1) | See (1) | See (1) | See (1) | See (1) |
MPU_AMBAIF_CLK | f/2 | f/2 | f/2 | f/2 | f/2 |
MPU_FMPU_FCLK | f/4 | f/4 | f/4 | f/4 | f/4 |
MPU_FL3REQ_FCLK | f/4 | f/4 | f/4 | f/8 | f/8 |
MPU_FM2E_FCLK | f/4 | f/4 | f/4 | f/4 | f/4 |
Some of the OPPs listed in Table 4-1 may not be supported for some devices.
For more information about the supported OPPs, see the "Operating Performance Points" section of the device Data Manual.
For more information about the DPLL_MPU, see DPLL_MPU Description, in Power, Reset, and Clock Management.
The two MPU cores cannot be clocked at different frequencies.
The realtime counter (COUNTER_REALTIME) is clocked by either WKUPAON_ICLK or FUNC_32K_CLK clocks, provided by the global PRCM module. By default, WKUPAON_ICLK is used as a COUNTER_REALTIME clock. When the MPU subsystem goes to standby mode, the counter automatically switches to a low-power mode using the FUNC_32K_CLK (SYS_CLK1/610).