SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
After the Host System goes into standby mode, the Host System can resume from standby via a wakeup event initiated by one of the following three events:
(1) Interrupt from a SD card: If an SD card interrupt occurs, the Host System can resume from standby mode. If the Host System uses this wakeup factor, SD Bus power shall be kept on.
(2) Insertion of SD card: If a SD card is inserted, the Host System can resume from standby mode.
(3) Removal of SD card: If a SD card is removed, the Host System can resume from standby mode.
The sequence for preparing wakeup before the Host System goes into standby mode is shown in Figure 12-136.
(1) Set MMCSD0_HOST_CONTROL1[1] DATA_WIDTH bit to 0.
(2) Execute SD Clock Stop Sequence as described in Section 12.3.6.4.1.2.2, SD Clock Supply and Stop Sequence.
(3) Clear the MMCSD0_NORMAL_INTR_STS register and the MMCSD0_NORMAL_INTR_SIG_ENA register, and then set the enable bits of each wakeup event factor to 1 in the MMCSD0_WAKEUP_CONTROL register and set the bits of MMCSD0_ERROR_INTR_STS_ENA register to use wakeup.
The sequence for wakeup once in standby mode is shown in Figure 12-137.
(1) Wait for wakeup event.
(2) Set the enable bits of each wakeup event factor to 0 in the MMCSD0_WAKEUP_CONTROL register and then clear event statuses in the MMCSD0_NORMAL_INTR_STS register. If necessary, set the MMCSD0_NORMAL_INTR_SIG_ENA register.
(3) Execute SD Clock Supply Sequence (see Section 12.3.6.4.1.2.2, SD Clock Supply and Stop Sequence).
(4) Set the SD Bus width (see Section 12.3.6.4.1.4, Changing Bus Width).