Table 8-7 Register Functions in Idle Mode
Function
Activated by
SCI 0 Receive-
Data-Full Other
Register
Interrupt
Activation
Initial Setting
Operation
Destination
Source
Destination or
Held fixed
address address
source
address
register
register
Source
Destination Source or
Held fixed
address address
destination
register
register
address
Transfer counter
Number of
Decremented
transfers
once per
transfer until
H'0000 is
reached and
transfer ends
Legend
MAR:
Memory address register
IOAR: I/O address register
ETCR: Execute transfer count register
MAR and IOAR specify the source and destination addresses. MAR specifies a 24-bit source or
destination address. IOAR specifies the lower 8 bits of a fixed address. The upper 16 bits are all
1s. MAR and IOAR are not incremented or decremented.
Figure 8-4 illustrates how idle mode operates.
Figure 8-4 Operation in Idle Mode
23
0
MAR
All 1s
IOAR
23
0
15
0
ETCR
7
Transfer
1 byte or word is
transferred per request
IOAR
MAR
210
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