Managing External Interrupts

Managing External Interrupts

The Challenge L, Challenge XL, and Onyx systems and their Power versions have four external-interrupt output jacks and four external-interrupt input jacks on their back panels. In these systems, the device special file /dev/ei represents a device driver that manages access to these external interrupt ports.

Using ioctl() calls to this device (see "Overview of Device Control"), your program can

enable and disable the detection of incoming external interrupts
set the strobe length of outgoing signals
strobe, or set a fixed level, on any of the four output ports

In addition, library calls are provided that allow very low-latency detection of an incoming signal.

For more information on external interrupt management, see Chapter 6, "Control of External Interrupts" and the ei(7) reference page.