Figure 5 aDIO Match Mode

Strobe Mode

Another interrupt mode supported by aDIO is Strobe mode. This allows the strobe pin of the DIO connector to trigger an interrupt. A low to high transition on the strobe pin will cause an interrupt request. The request will remain high until the Clear Register is read from. Additionally, the Compare Register latched in the value at Port 0 when the Strobe pin made a low to high transition. No further strobes will be available until a read of the Compare Register is made. You must read the Compare Register, and then clear interrupts so that the latched value in the compare register is not lost. To enter Strobe mode, set bits [4:3] of the DIO-Control register to “01”.

Wake-on-aDIO

The aDIO Strobe, Match and Event interrupt can be used to generate a wake event. This event can wake the CPU from any power-down mode, including Soft-Off (S5). Wake from aDIO will work as long at +5V Standby power is applied to the board. To use the aDIO to wake the system, Wake from aDIO must first be enabled in the BIOS setup utility. Then the aDIO is configured in the appropriate interrupt mode. The “Wake Enable” bit is then set in the Wake Control Register at 0x454. The CPU can then be placed in a standby mode, and the aDIO interrupt will wake the system.

During system standby, a 32kHz clock is used for the aDIO instead of an 8.33 MHz clock. Therefore, transitions must be at least 30 us in order to trigger a wake event.

If the aDIO is to be used for a wake event only, and not an interrupt, the “Int Mask” bit can be set in the Wake Control Register. This will block the interrupt, but still allow a wake event to occur. The various settings for “Wake Enable” and “Int Mask” are shown in Table 46 below.

Table 46 Interrupt and Wake Event Generation

WakeEnable Int Mask

Function

 

 

00 No Interrupt or Wake event is generated

0

1

Interrupt Only

1

0

Wake Event Only

1

1

Interrupt and Wake Event

 

 

 

BDM-610000050 Rev A

Chapter 4: Using the cpuModule 59

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IBM CMX58886CX user manual Wake-on-aDIO, Interrupt and Wake Event Generation, WakeEnable Int Mask Function