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6.1 Overview
The H8/3048 Series has an on-chip bus controller that divides the address space into eight areas
and can assign different bus specifications to each. This enables different types of memory to be
connected easily.
A bus arbitration function of the bus controller controls the operation of the DMA controller
(DMAC) and refresh controller. The bus controller can also release the bus to an external device.
6.1.1 Features
Features of the bus controller are listed below.
•
Independent settings for address areas 0 to 7
— 128-kbyte areas in 1-Mbyte modes; 2-Mbyte areas in 16-Mbyte modes.
— Chip select signals (CS
— Areas can be designated for 8-bit or 16-bit access.
— Areas can be designated for two-state or three-state access.
•
Four wait modes
— Programmable wait mode, pin auto-wait mode, and pin wait modes 0 and 1 can be
selected.
— Zero to three wait states can be inserted automatically.
•
Bus arbitration function
— A built-in bus arbiter grants the bus right to the CPU, DMAC, refresh controller, or an
external bus master.
Section 6 Bus Controller
to CS
) can be output for areas 0 to 7.
0
7
111
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