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VxWorks

BSP Developer’s Guide, 6.0

3.2.7 Interrupt Controllers

The generic interrupt controller device drivers reside in the directory

target/src/drv/intrCtl. See the template driver, templateIntrCtl.c, for detailed

information on interrupt controller driver design and construction.

Certain CPU architectures use external interrupt controllers to receive and

prioritize external device interrupts. Wind River has prepared a draft document to

define a standard interrupt controller device interface. To see this document, go to

the Wind River Online Support Web site and look under Wind River Technical Notes.

3.2.8 ISR Guidelines

After the kernel is started, use the intConnect( ) routine and the INUM_TO_IVEC

macro to connect interrupt service routines (ISRs) to the interrupt vector table. For

example:

intConnect (INUM_TO_IVEC (intVec), proc, param );

The intVec parameter is the interrupt vector, proc is the C routine to call in response

to the interrupt, and param is a parameter to pass the proc routine.

A common mistake made when writing ISRs is to omit the interrupt

acknowledgement needed to clear the interrupt source. The undesirable result of

this omission is the immediate generation of another interrupt as soon as the ISR

completes.

3.2.9 DMA

VxWorks does not currently impose a DMA driver model. DMA support is

optional, and the architecture of such support is left to the implementation.

3.2.10 Minimum Required Drivers

The only driver required by VxWorks is the system clock, although certain

architectures, such as Intel Architecture and PowerPC, also require an interrupt

controller driver.

Implementing a system clock driver typically involves using one of the existing

drivers from target/src/drv/timer (and target/src/drv/intrCtl, if an interrupt

controller driver is required). If you are reusing an existing driver, all you need to

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RAM 6.0 BUX II Series Guía de usuario Pagina 78