Intel C2518 FH8065501516710 Data Sheet

Intel

®

 Atom™ Processor C2000 Product Family for Microserver

Datasheet, Vol. 2 of 3

September 2014

494

Order Number: 330061-002US

The serialized IRQ protocol has two modes of operation which affect the start frame:

• Continuous Mode - The interrupt controller solely generates the start frame.
• Quiet Mode - The peripheral initiates the start frame, and the interrupt controller 

completes it.

These modes are programmed during the stop frame period discussed later in the 

chapter. The continuous mode must be entered first, to start the first frame. The start 

frame duration is eight LPC clock periods. This is considered an interrupt polling mode.

In quiet mode, the 

 line remains inactive (the signal floats) and is pulled-

up between the stop frame and start frame until a peripheral drives 

 low. 

The SoC serialized interrupt controller senses the line low and drives it low for the 

remainder of the start frame. Since the first LPC clock of the start frame was driven by 

the peripheral, the interrupt controller drives 

 low for 1 LPC clock less than 

in the continuous mode. This mode of operation allows for lower-power operation.

Refer to the Intel

(BWG), Volume 2 of 2 - Section 12.2 and 12.3 for additional IRQ programming details.