245
8.5.3
Idle Mode
Idle mode can be specified by setting the RPE bit and DTIE bit in DMACR to 1. In idle mode, one
byte or word is transferred in response to a single transfer request, and this is executed the number
of times specified in ETCR.
One address is specified by MAR, and the other by IOAR. The transfer direction can be specified
by the DTDIR bit in DMACR.
Table 8-7 summarizes register functions in idle mode.
Table 8-7
Register Functions in Idle Mode
Function
Register
DTDIR = 0 DTDIR = 1 Initial Setting
Operation
23
0
MAR
Source
address
register
Destination
address
register
Start address of
transfer destination
or transfer source
Fixed
23
0
IOAR
15
H'FF
Destination
address
register
Source
address
register
Start address of
transfer source or
transfer destination
Fixed
0
15
ETCR
Transfer counter
Number of transfers Decremented every
transfer; transfer
ends when count
reaches H'0000
Legend
MAR
: Memory address register
IOAR : I/O address register
ETCR : Transfer count register
DTDIR : Data transfer direction bit
MAR specifies the start address of the transfer source or transfer destination as 24 bits. MAR is
neither incremented nor decremented each time a byte or word is transferred.
IOAR specifies the lower 16 bits of the other address. The 8 bits above IOAR have a value of
H'FF.
Содержание H8S/2631
Страница 28: ...xviii Appendix G Package Dimensions 1154 ...
Страница 341: ...316 Transfer SAR or DAR DAR or SAR Block area First block Nth block Figure 9 8 Memory Mapping in Block Transfer Mode ...
Страница 918: ...905 ø DREQ0 DREQ1 tDRQS tDRQH Figure 25 19 DMAC DREQ Input Timing ...
Страница 955: ...943 A 2 Instruction Codes Table A 2 shows the instruction codes ...