Maxim-integrated 78Q8430 Software Driver Manual do Utilizador descarregar pdf (Página 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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Maxim-integrated 78Q8430 Software Driver Manual do Utilizador Página 44