Intel IXP400 manual Polled Mode Operations, Interrupt Servicing of Target Time Reached Condition

Intel® IXP400 Software

Access-Layer Components: Time Sync (IxTimeSyncAcc) API

2.Auxiliary Master Timestamp

3.Auxiliary Slave Timestamp

In order to avoid repeated invocation of the Interrupt Service Routing for the “target time reached” condition, the client application callback routine will need to either disable the interrupt handling, invoke the API to set the target time to a different value, or change the system timer value.

Figure 98 presents a scenario where the system time and target time are set, a “target time reached” condition is met, and an interrupt is used to notify the client application. A polled-mode scenario would operate similarly to what is described in “Polled Mode Operations” on page 291.

Figure 98. Interrupt Servicing of Target Time Reached Condition

Client Application	IxTimeSyncAcc		IEEE 1588 Hardware Assist Block
	ixTimeSyncAccSystemTimeSet (systemTime)
	ixTimeSyncAccTickRateSet (tickRate)	Set system time
	ixTimeSyncAccTargetTimeSet(targetTime)	Set frequency scaling factor
ixTimeSyncAccTargetTimeInterruptEnable(targetTimeCallback)		Set target time
		Enable Target Time Interrupt
		Register Callback
		Invoke ISR	System Time >= Target Time
			Interrupt Triggered
		Get target time
		Invoke Callback
	(*IxTimeSyncAccTargetTimeCallback)(targetTime)
			B4394-01

20.4.3Polled Mode Operations

Target Time events and Auxiliary snapshots can also be serviced with polling by the client application. Figure 99 shows a scenario where the client application uses polling to periodically retrieve auxiliary snapshot data.

Programmer’s Guide	IXP400 Software Version 2.0	April 2005
	Document Number: 252539, Revision: 007	291