Datasheet

XMEGA B [DATASHEET]

8291B–AVR–01/2013

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 5-8 on page 59

shows the base value for all modules and peripherals. Table 5-9 on page 60 to Table 5-11 on page 60 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 peripheral with the request. Refer to the dif-

ferent peripheral chapters for how requests are generated and cleared.

Table 5-8. DMA trigger source base values for all modules and peripherals.

Bit 76543210

+0x03 TRIGSRC[7:0]

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

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 trigger value

0x40 TCC0 Timer/counter C0 DMA triggers base value

0x46 TCC1 Timer/counter C1 triggers base value

0x4A SPIC SPI C DMA trigger value

0x4B USARTC0 USART C0 DMA triggers base value

0x60 TCD0 Timer/counter D0 DMA triggers base value

0x6A SPID SPI D DMA triggers value

0x6B USARTD0 USART D0 DMA triggers base value

0x80 TCE0 Timer/counter E0 DMA triggers base value

0x8B USARTE0 USART E0 DMA triggers base value

0xA0 TCF0 Timer/counter F0 DMA triggers base value

0xAB USARTF0 USART F0 DMA triggers base value