Maxim Integrated 78Q8430 Software Driver - Manual (Page 44)

78Q8430 Software Driver Development Guidelines UG_8430_004
9 Power Management
9.1 Sleep Procedure
Use the following procedure to setup the sleep state and specify the wake event interrupt:
STEP 1: Read the PMCSR value.
STEP 2: Modify the PS bits to anything non-zero (e.g. 0x01).
The wake event only occurs if one or both of the PS bits are set (non-zero).
STEP 3: Set the wake event interrupt.
If desired, enable the PME interrupt by setting the PME_ENB bit in the PMCSR value. If not using
the PME interrupt, enable the WAKE interrupt in the HIMR.
STEP 4: Write the new value back to the PMCSR.
Do not modify PMCSR bits 16-31 in this procedure.
9.2 Wake Event Procedure
Use the following procedure to process a wake event:
STEP 1: Read the PMCSR value.
STEP 2: Verify that the PME bit is set.
STEP 3: Clear the PS bits.
STEP 4: Write the modified value back to the PMCSR.
Do not modify PMCSR bits 16-31 in this procedure.
STEP 5: Read the WUSR to determine the CAM rule that triggered the wake event.
This is useful if the host wants to know the source of the wake event.
STEP 6: Execute a software reset.
It is important that the software execute steps 1 through 4 of this procedure as soon as possible
after the wake event because this stops the HNR counter and potentially prevent the transmission
of a Host Not Responding frame. Steps 5 and 6 of the procedure are not time critical.
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