SuperH (SH) 64-Bit RISC Series SH-5 System Architecture, Volume ...

PRELIMINARY DATA96 Operation5.3 OperationThe system presents request to the peripheral bridge when it wishes to accessperipheral devices. It uses the address to determine which region or device is beingaccessed.5.3.1 Bridge registersIf the address of the operation is the bridge area of the peripheral subsystem, it istrapped locally and used to access information stored within the bridge.If the access is to the bridge status area, it is not passed to the external peripheralsand is used to access information about the bridge implementation, past erroneousoperations and other status information associated with peripherals attached to thissystem.The following operations are supported to this region:• load eight bytes,• store eight bytes.If a mask bit is not asserted, or, any other operation is presented to this area anerror is returned and the bit BAD_OPC is asserted in the VCR register.If an access occurs to an reserved address within this area, an error is returned andthe bit BAD_ADDR is asserted in the VCR register.5.3.2 SuperHyway type 2 areaOperations onto the SuperHyway type 2 area are mapped onto the externalinterface. This is organized as a single region whose address decode is completedexternally to the peripheral bridge.If the interface is disabled (as indicated by the associated pin) then all accesses tothis interface are treated as if the area is reserved, an error is returned and the bitBAD_ADDR is asserted in the VCR register.D R A FTIf the interface is enabled, then the information is passed across the interface usingthe standard protocols.SuperH, Inc.SH-5 System Architecture, Volume 1: System 05-SA-10001 v1.0