When would I use level triggered interrupts, not edge ?
Submitted By: Phillip M. Gallo FAQ Last Modified: 08/09/06
- The edge-triggered interrupt is the most common mode for External Interrupts. An event occurs, the edge causes the interrupt service to invoked to perform that which is required.
- Read/write a byte; check the int. flag to see if the device is satisfied and if not read/write again until it is.
- Read/write one byte, exit the interrupt, with the interrupt being re-invoked until the device is satisfied.
The level Sensitive interrupt is provided for "burst" operations. FIFO's or devices intended for DMA (IDE xface) interfaces often assert a signal indicating service is required and keep it asserted until fully satisfied.
The Level activated interrupt can be accomodated in one of two ways:
The second methodology has more overhead but is simpler to write (not by much, however).
one more reason for level activation
Submitted By: Erik Malund FAQ Last Modified: 08/09/06
- one more reason for level activation is that for derivatives that can be brought out of sleep mode level activation is required
Erik
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