Atmel SAM9X25, Manual

Page: 479 / 1145

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11054A–ATARM–27-Jul-11
SAM9X25
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11054A–ATARM–27-Jul-11
SAM9X25
31.4.4.2 Programming DMAC for Multiple Buffer Transfers
Notes: 1. USR means that the register field is manually programmed by the user.
2. CONT means that address are contiguous.
3. REP means that the register field is updated with its previous value. If the transfer is the first one, then the user must manu-
ally program the value.
4. Channel stalled is true if the relevant BTC interrupt is not masked.
5. LLI means that the register field is updated with the content of the linked list item.
Replay Mode of Channel Registers
During automatic replay mode, the channel registers are reloaded with their initial values at the
completion of each buffer and the new values used for the new buffer. Depending on the row
number in
Table 31-3 on page 479 , some or all of the DMAC_SADDRx, DMAC_DADDRx,
DMAC_CTRLAx and DMAC_CTRLBx channel registers are reloaded from their initial value at
the start of a buffer transfer.
Contiguous Address Between Buffers
In this case, the address between successive buffers is selected to be a continuation from the
end of the previous buffer. Enabling the source or destination address to be contiguous between
Table 31-3. Multiple Buffers Transfer Management Table
Transfer Type AUTO SRC_REP DST_REP SRC_DSCR DST_DSCR BTSIZE DSCR SADDR DADDR Other Fields
1) Single Buffer or Last
buffer of a multiple buffer
transfer
0 – – – – USR 0 USR USR USR
2) Multi Buffer transfer with
contiguous DADDR
0 – 0 0 1 LLI USR LLI CONT LLI
3) Multi Buffer transfer with
contiguous SADDR
0 0 – 1 0 LLI USR CONT LLI LLI
4) Multi Buffer transfer with
LLI support
0 – – 0 0 LLI USR LLI LLI LLI
5) Multi Buffer transfer with
DADDR reloaded
0 – 1 0 1 LLI USR LLI REP LLI
6) Multi Buffer transfer with
SADDR reloaded
0 1 – 1 0 LLI USR REP LLI LLI
7) Multi Buffer transfer
with BTSIZE reloaded and
contiguous DADDR
1 – 0 0 1 REP USR LLI CONT LLI
8) Multi Buffer transfer with
BTSIZE reloaded and
contiguous SADDR
1 0 – 1 0 REP USR CONT LLI LLI
9) Automatic mode channel
is stalling
BTsize is reloaded
1 0 0 1 1 REP USR CONT CONT REP
10) Automatic mode
BTSIZE, SADDR and
DADDR reloaded
1 1 1 1 1 REP USR REP REP REP
11) Automatic mode
BTSIZE, SADDR reloaded
and DADDR contiguous
1 1 0 1 1 REP USR REP CONT REP