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8068C–AVR–06/08
XMEGA A3
9. Event System
9.1 Features
• Inter-peripheral communication and signalling with minimum latency
• CPU and DMA independent operation
• 8 Event Channels allows for up to 8 signals to be routed at the same time
• Events can be generated by
– Timer/Counters (TCxn)
– Real Time Counter (RTC)
– Analog to Digital Converters (ADCx)
– Analog Comparators (ACx)
– Ports (PORTx)
– System Clock (Clk
SYS
)
– Software (CPU)
• Events can be used by
– Timer/Counters (TCxn)
– Analog to Digital Converters (ADCx)
– Digital to Analog Converters (DACx)
– Ports (PORTx)
– DMA Controller (DMAC)
– IR Communication Module (IRCOM)
• The same event can be used by multiple peripherals for synchronized timing
• Advanced Features
– Manual Event Generation from software (CPU)
– Quadrature Decoding
– Digital Filtering
• Functions in Active and Idle mode
9.2 Overview
The Event System is a set of features for inter-peripheral communication. It enables the possibil-
ity for a change of state in one peripheral to automatically trigger actions in one or more
peripherals. What changes in a peripheral that will trigger actions in other peripherals are config-
urable by software. It is a simple, but powerful system as it allows for autonomous control of
peripherals without any use of interrupts, CPU or DMA resources.
The indication of a change in a peripheral is referred to as an event, and is usually the same as
the interrupt conditions for that peripheral. Events are passed between peripherals using a dedi-
cated routing network called the Event Routing Network. Figure 9-1 on page 16 shows a basic
block diagram of the Event System with the Event Routing Network and the peripherals to which
it is connected. This highly flexible system can be used for simple routing of signals, pin func-
tions or for sequencing of events.
The maximum latency is two CPU clock cycles from when an event is generated in one periph-
eral, until the actions are triggered in one or more other peripherals.
The Event System is functional in both Active and Idle modes.
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