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Chapter 26 DMA Controller
3.DMA Controller (DMAC) Operation
● Disabling all channels
If the operation of all channels is disabled with the DMA operation enable bit DMAE, all DMAC operations,
including operations on active channels, are stopped. Then, even if the operation of all channels is enabled again,
no transfer is performed unless a channel is restarted. In this case, no interrupt whatever occurs.
■ Stopping Due To an Error
In addition to normal end after transfer for the number of times specified, stopping as the result of various types of
errors and the forced stopping are provided.
● Transfer stop requests from peripheral circuits
Depending on the peripheral circuit that outputs a transfer request, a transfer stop request is issued when an
error is detected (Example: Error when data is received at or sent from a communications system peripheral).
The DMAC, when it receives such a transfer stop request, displays "Transfer stop request" as the end code and
stops the transfer on the corresponding channel.
Table 3-6 Stopping due to an Error
*1 : A transfer stop request is issued when an error is detected
For details of the conditions under which a transfer stop request is generated, see the specifications for each
peripheral circuit.
IS EIS Function Transfer stop request
10110
11000
11010
11100
0000
0000
0000
0000
USART 0 RX *1
USART 1 RX *1
USART 4 RX *1
USART 5 RX *1
Yes
Yes
Yes
Yes
10000
10010
10100
10110
11000
11010
11100
11110
0011
0011
0011
0011
0011
0011
0011
0011
USART 0 RX *1
USART 1 RX *1
USART 2 RX *1
USART 3 RX *1
USART 4 RX *1
USART 5 RX *1
USART 6 RX *1
USART 7 RX *1
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
10000
10010
10100
10110
11000
11010
11100
11110
0100
0100
0100
0100
0100
0100
0100
0100
USART 8 RX *1
USART 9 RX *1
USART 10 RX *1
USART 11 RX *1
USART 12 RX *1
USART 13 RX *1
USART 14 RX *1
USART 15 RX *1
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
others others None