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6.5.3. Ping-Pong Transfer
In ping-pong transfer mode, the DMAC performs basic transfers repeatedly while switching
between the primary data structure and alternate data structure. The data structures are referred
alternately, and DMA transfer is terminated when the control data with cycle_ctrl set to 0x0 is
referred. A transfer completion interrupt occurs each time a transfer using a data structure is
completed.
DMA transfer request
DMA transfer request
DMA transfer request
DMA transfer request
DMA transfer request
S1C31D50 TECHNICAL MANUAL
(Rev. 1.00)
Transfer using primary data structure
(cycle_ctrl = 0x3, 2R = 4, N = 6)
Task A
(cycle_ctrl = 0x3, 2R = 2, N = 2)
Task C
(cycle_ctrl = 0x3, 2R = 4, N = 7)
Task E
Figure 6.5.3.1 Ping-Pong Transfer Operation Example
Seiko Epson Corporation
Transfer using alternate data structure
DMA transfer
completion interrupt
DMA transfer request
DMA transfer request
DMA transfer request
DMA transfer
completion interrupt
DMA transfer request
DMA transfer request
DMA transfer
completion interrupt
(cycle_ctrl = 0x3, 2R = 4, N = 12)
Task B
DMA transfer
completion interrupt
(cycle_ctrl = 0x3, 2R = 4, N = 5)
Task D
DMA transfer
completion interrupt
(cycle_ctrl = 0x0)
Termination
6-7
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