Intel 80312 I/O Companion Chip - ECEE

Intel ® 80200 Processor based on Intel ®XScale Microarchitecture CoreInterface Unit 8This chapter describes the Intel ® 80200 processor based on XScale microarchitecture (ARMarchitecture compliant) Core Interface Unit (CIU).8.1 OverviewThe Core Interface Unit (CIU) is a bridge between the Intel ® 80200 processor and the Intel ® 80312I/O companion chip. The Intel ® 80312 I/O companion chip makes all of the chip’s resourcesavailable for control by the Intel ® 80200 processor via the CIU. The Intel ® 80200 processorcommunicates with the Intel ® 80312 I/O companion chip using the Intel ® 80200 processorRequest Bus which is comprised of two elements:1. A synchronous command bus provides the CIU with a read or write command, a transferlength and a start address.2. The Intel ® 80312 I/O companion chip SDRAM 64-bit data bus (DQ) transfers data associatedwith the Intel ® 80200 processor request bus commands. The data bus is shared by the Intel ®80200 processor request bus and the Intel ® 80312 I/O companion chip internal SDRAMmemory control unit (MCU).The CIU accepts Intel ® 80200 processor request bus accesses. It forwards read accesses to the IBand returns the read data. It completes write accesses for the Intel ® 80200 processor. DuringSDRAM reads Intel ® 80200 processor receives data directly from the SDRAM. For other readaccesses (Flash reads and PCI reads) CIU provides data received on the IB. Data for writesgenerated by the Intel ® 80200 processor is forwarded to IB by the CIU.All accesses received by the CIU from the Intel ® 80200 processor are processed in order.TheCIUistheonlyagentontheIntel ® 80200 processor request bus. See Figure 8-1.Figure 8-1.Intel ® 80200 Processor Bus Controller Unit Block DiagramIntel® 80312 I/O Companion ChipSDRAMMemory ControllerIntel® 80200 Processor Data BusIntel® 80200 Processor Request Bus80200 Processor Core Interface UnitInternal Bus (IB)The CIU forwards Intel ® 80200 processor request bus accesses to the internal bus and isresponsible for their completion. No address translation is performed by the CIU.Developer’s Manual 8-1