SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 364

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

Figure 23-8. DMAC Transfer with Linked List Source Address and Contiguous Destination Address
364
364
SAM3X/A
SAM3X/A
Source Layer
Address of
SADDR(1)
SADDR(0)
SADDR(2)
Note:
The DMAC transfer might look like that shown in
tion address is decrementing.
The DMAC transfer flow is shown in
15. Once the buffer of data is transferred, the DMAC_CTRLAx register is written out to the
16. The DMAC does not wait for the buffer interrupt to be cleared, but continues and
system memory at the same location and on the same layer
(DMAC_DSCRx.DSCR_IF) where it was originally fetched, that is, the location of the
DMAC_CTRLAx register of the linked list item fetched prior to the start of the buffer
transfer. Only DMAC_CTRLAx register is written out because only the
DMAC_CTRLAx.BTSIZE and DMAC_CTRLAX.DONE fields have been updated by
DMAC hardware. Additionally, the DMAC_CTRLAx.DONE bit is asserted when the buf-
fer transfer has completed.
fetches the next LLI from the memory location pointed to by the current DMAC_DSCRx
register, then automatically reprograms the DMAC_SADDRx, DMAC_CTRLAx,
DMAC_CTRLBx and DMAC_DSCRx channel registers. The DMAC_DADDRx register
is left unchanged. The DMAC transfer continues until the DMAC samples the
DMAC_CTRLAx, DMAC_CTRLBx and DMAC_DSCRx registers at the end of a buffer
transfer match that described in Row 1 of
knows that the previous buffer transferred was the last buffer in the DMAC transfer.
Do not poll the DMAC_CTRLAx.DONE bit in the DMAC memory map. Instead, poll the
LLI.DMAC_CTRLAx.DONE bit in the LLI for that buffer. If the poll LLI.DMAC_CTRLAx.DONE bit is
asserted, then this buffer transfer has completed. This LLI.DMAC_CTRLAx.DONE bit was cleared
at the start of the transfer.
Source Buffers
Buffer 0
Buffer 1
Buffer 2
Figure 23-9 on page
Destination Buffers
Buffer 0
Buffer 2
Buffer 1
Table 23-4 on page
Figure 23-8 on page
365.
DADDR(2)
DADDR(1)
DADDR(0)
Destination Layer
355. The DMAC then
Address of
364. Note that the destina-
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12