Functional Overview - Hitachi H8/3048 Hardware Manual

8.1.3 Functional Overview

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Table 8-1 gives an overview of the DMAC functions.
Table 8-1 DMAC Functional Overview
Transfer Mode
Short I/O mode
address • Transfers one byte or one word
mode per request
• Increments or decrements the
memory address by 1 or 2
• Executes 1 to 65,536 transfers
Idle mode
• Transfers one byte or one word
per request
• Holds the memory address fixed
• Executes 1 to 65,536 transfers
Repeat mode
• Transfers one byte or one word
per request
• Increments or decrements the
memory address by 1 or 2
• Executes a specified number (1 to
255) of transfers, then returns to
the initial state and continues
Full Normal mode
address • Auto-request
mode — Retains the transfer request
internally
— Executes a specified number
(1 to 65,536) of transfers
continuously
— Selection of burst mode or
cycle-steal mode
• External request
— Transfers one byte or one word
per request
— Executes 1 to 65,536 transfers
Block transfer
• Transfers one block of a specified
size per request
• Executes 1 to 65,536 transfers
• Allows either the source or
destination to be a fixed block
area
• Block size can be 1 to 255 bytes
or words
Activation
• Compare match/input 24
capture A interrupts
from ITU channels
0 to 3
• Transmit-data-empty
interrupt from SCI
channel 0
• Receive-data-full
interrupt from SCI
channel 0
• External request
• Auto-request
• External request
• Compare match/
input capture A
interrupts from ITU
channels 0 to 3
• External request
187
Address
Reg. Length
Destina-
Source tion
8
8 24
24 8
24 24
24 24