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XMEGA A [MANUAL]
8077I–AVR–11/2012
The group configuration is the “base_offset;” for example, TCC1_CCA for the timer/counter C1 CC channel A the transfer
trigger.
5.14.5 TRFCNTL – Channel Block Transfer Count register Low
The TRFCNTH and TRFCNTL register pair represents the 16-bit value TRFCNT. TRFCNT defines the number of bytes
in a block transfer. The value of TRFCNT is decremented after each byte read by the DMA channel. When TRFCNT
reaches zero, the register is reloaded with the last value written to it.
Bit 7:0 – TRFCNT[7:0]: Channel n Block Transfer Count low byte
These bits hold the LSB of the 16-bit block transfer count.
The default value of this register is 0x1. If a user writes 0x0 to this register and fires a DMA trigger, DMA will be doing
0xFFFF transfers.
5.14.6 TRFCNTH – Channel Block Transfer Count register High
Bit 7:0 – TRFCNT[15:8]: Channel n Block Transfer Count high byte
These bits hold the MSB of the 16-bit block transfer count.
The default value of this register is 0x1. If a user writes 0x0 to this register and fires a DMA trigger, DMA will be doing
0xFFFF transfers.
5.14.7 REPCNT – Repeat Counter register
REPCNT counts how many times a block transfer is performed. For each block transfer, this register will be
decremented.
used to control when the transaction is complete. The counter is decremented after each block transfer if the DMA has to
serve a limited number of repeated block transfers. When repeat mode is enabled, the channel is disabled when
REPCNT reaches zero and the last block transfer is completed. Unlimited repeat is achieved by setting this register to
zero.
Bit
7
65
43
210
+0x04
TRFCNT[7:0]
Read/Write
R/W
Initial Value
0
00
001
Bit
76543210
+0x05
TRFCNT[15:8]
Read/Write
R/W
Initial Value
00000000
Bit
7
6543210
+0x06
REPCNT[7:0]
Read/Write
R/W
Initial Value
0
0000000