The TO_MCU sequence first turns off rails and GPIOs which are assigned to the SOC power group. The sequence enables the MCU rails, in the event that they are not already active (when transitioning from STANDBY to MCU_ONLY for example). There are two cases for this sequence, based off the value stored in the I2C_7 register bit. The I2C_7 setting must be the same in each PMIC before triggering the sequence. If the bit is low, then EN_EXT_VDDR is disabled; Figure 6-10. If the I2C_7 bit is high, then EN_EXT_VDDR is enabled; Figure 6-9.

The first instructions of the TO_MCU sequence perform writes to the MISC_CTRL and ENABLE_DRV_STAT registers.

// Set AMUXOUT_EN, CLKMON_EN
// Clear LPM_EN, NRSTOUT_SOC 
REG_WRITE_MASK_IMM ADDR=0x81 DATA=0x18 MASK=0xE1
// Clear SPMI_LP_EN
REG_WRITE_MASK_IMM ADDR=0x82 DATA=0x00 MASK=0xEF

Figure 6-9 TO_MCU with I2C_7 high in both PMICs

Figure 6-10 TO_MCU Sequence with I2C_7 low in both PMICs

The last instructions of the TO_MCU sequence also perform writes to the MISC_CTRL and ENABLE_DRV_STAT registers after the delay defined in the PFSM_DELAY_REG_1.

SREG_READ_REG ADDR=0xCD REG=R1
DELAY_SREG R1
// Clear SPMI_LPM_EN and FORCE_EN_DRV_LOW 
REG_WRITE_MASK_IMM ADDR=0x82 DATA=0x00 MASK=0xE7
// Set NRSTOUT (MCU_PORZ)
REG_WRITE_MASK_IMM ADDR=0x81 DATA=0x01 MASK=0xFE