Atmel AVR XMEGA AU series, Manual

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65
8331B–AVR–03/12
Atmel AVR XMEGA AU
5.14.4 TRIGSRC – Trigger Source
• Bit 7:0 – TRIGSRC[7:0]: Channel Trigger Source Select
These bits select which trigger source is used for triggering a transfer on the DMA channel. A
zero value means that the trigger source is disabled. For each trigger source, the value to put in
the TRIGSRC register is the sum of the module’s or peripheral’s base value and the offset value
for the trigger source in the module or peripheral.
Table 5-9 on page 65 shows the base value for
all modules and peripherals. Table 5-10 on page 66 to Table 5-13 on page 67 shows the offset
value for the trigger sources in the different modules and peripheral types. For modules or
peripherals which do not exist for a device, the transfer trigger does not exist. Refer to the device
datasheet for the list of peripherals available.
If the interrupt flag related to the trigger source is cleared or the interrupt level enabled so that an
interrupt is triggered, the DMA request will be lost. Since a DMA request can clear the interrupt
flag, interrupts can be lost.
Note: For most trigger sources, the request is cleared by accessing a register belonging to the periph-
eral with the request. Refer to the different peripheral chapters for how requests are generated
and cleared.
Table 5-8. DMA channel destination address mode settings.
DESTDIR[1:0] Group Configuration Description
00 FIXED Fixed
01 INC Increment
10 DEC Decrement
11 - Reserved
Bit 7 6 5 4 3 2 1 0
+0x03 TRIGSRC[7:0] TRIGSRC
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 0 0 0 0 0 0 0 0
Table 5-9. DMA trigger source base values for all modules and peripherals.
TRIGSRC Base Value Group Configuration Description
0x00 OFF Software triggers only
0x01 SYS Event system DMA triggers base value
0x04 AES AES DMA trigger value
0x10 ADCA ADCA DMA triggers base value
0x15 DACA DACA DMA trigger bas
0x20 ADCB ADCB DMA triggers base value
0x25 DACB DACB DMA triggers base value
0x40 TCC0 Timer/counter C0 DMA triggers base value
0x46 TCC1 Timer/counter C1 triggers base value