Introduction - Analog Devices VisualDSP++ 5.0 Service Manual

Introduction

Introduction
Using the capabilities of other system services, the flag service allows the
client control over the direction of flags, values placed on or sensed from a
flag pin, and notification of the client upon flag pin changes, via live or
deferred callbacks.
The use of the flag service is dependent on the use of both the interrupt
manager and the deferred callback (DCB) manager for its full operation.
If callbacks are not deferred, but rather are live, the DCB manager is not
required. If callbacks are not required, neither the interrupt manager nor
DCB manager is required.
Currently, the flag service is available for use with the Blackfin
ADSP-BF531/532/533 processors, ADSP-BF534/536/537 processors,
and ADSP-BF561 processors.
In order to reduce the pin count of devices, flag pins are sometimes muxed
onto the same pins as other peripherals. The flag service does not provide
arbitration functionality to control pin muxing. It is the responsibility of
the client program to ensure that peripherals and the flag service do not
use the same pin simultaneously. For the ADSP-BF531/532/533 and
ADSP-BF561 processors, this entails ensuring that the relevant peripheral
control registers are correctly set. For ADSP-BF534/536/537 processors,
the flag service automatically invokes the port control service to effect any
pin mux changes. No user intervention is required.
For ADSP-BF531/532/533 and ADSP-BF561 processor cores, this entails
ensuring that the relevant peripheral control registers are correctly set. For
ADSP-BF534/536/537 processor cores, the port control registers are
required to be set accordingly. The latter can be managed via the port con-
trol service within the system services library. (Note that device drivers for
ADSP-BF534/536/537 processors automatically make the appropriate
calls into the port control service without any user intervention.)
7-2 VisualDSP++ 5.0 Device Drivers and System
Services Manual for Blackfin Processors