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7721 Group User’s Manual
13-12
DMA CONTROLLER
13.2 Block description
13.2.4 Source address register i (SARi)
Source address register i (hereafter called SARi) is a 24-bit register with a latch.
SARi indicates the transfer source address of the data to be transferred next.
The SARi latch has the following functions:
Maintains the value written to the address of SARi (in the single transfer and repeat transfer modes).
Indicates the start address of the transfer parameter memory of the next block (in the array chain
transfer and link array chain transfer modes).
When a value is written into the address of SARi, the same value is written into SARi and the SARi latch.
When writing a value to the address of SARi, all 24 bits must be written.
The contents of SARi can be read by reading the address of SARi; however, the value of the SARi latch
cannot be read. (Refer to “Tables 13.2.4 and 13.2.5.”)
13.2.5 Destination address register i (DARi)
Destination address register i (hereafter called DARi) is a 24-bit register with a latch.
DARi indicates the transfer destination address of the data to be transferred next.
The DARi latch maintains the value written to the address of DARi.
When a value is written into the address of DARi, the same value is written into DARi and the DARi latch.
When writing a value to the address of DARi, all 24 bits must be written.
The contents of DARi can be read by reading the address of DARi; however, the value of the DARi latch
cannot be read. (Refer to “Tables 13.2.4 and 13.2.5.”)
13.2.6 Transfer counter register i (TCRi)
Transfer counter register i (hereafter called TCRi) is a 24-bit register with a latch.
TCRi indicates the number of remaining bytes of the block under transfer.
The TCRi latch has the following functions:
Maintains the value written to the address of TCRi (in the single transfer and repeat transfer modes).
Indicates the number of remaining blocks (in the array chain transfer mode).
When a value is written into the address of TCRi, the same value is written into TCRi and the TCRi latch.
When writing a value to the address of TCRi, all 24 bits must be written.
The contents of TCRi can be read by reading the address of TCRi; however, the value of the TCRi latch
cannot be read. (Refer to “Tables 13.2.4 and 13.2.5.”)
Table 13.2.4 Addresses of SARi, DARi, and TCRi
Channel
0
1
2
3
Source address register i
(SARi)
1FC216–1FC016
1FD216–1FD016
1FE216–1FE016
1FF216–1FF016
Destination address
register i (DARi)
1FC616–1FC416
1FD616–1FD416
1FE616–1FE416
1FF616–1FF416
1FCA16–1FC816
1FDA16–1FD816
1FEA16–1FE816
1FFA16–1FF816
Transfer counter register i
(TCRi)