Atmel XMEGA B, User Manual

Page: 67 / 415

67 XMEGA B [DATASHEET]
8291B–AVR–01/2013
Figure 6-2. Example of event source, generator, user, and action.
Events can also be generated manually in software.
6.3.1 Signaling Events
Signaling events are the most basic type of event. A signaling event does not contain any information apart from the
indication of a change in a peripheral. Most peripherals can only generate and use signaling events. Unless otherwise
stated, all occurrences of the word ”event” are to be understood as meaning signaling events.
6.3.2 Data Events
Data events differ from signaling events in that they contain information that event users can decode to decide event
actions based on the receiver information.
Although the event routing network can route all events to all event users, those that are only meant to use signaling
events do not have decoding capabilities needed to utilize data events. How event users decode data events is shown in
Table 6-1 on page 68 .
Event users that can utilize data events can also use signaling events. This is configurable, and is described in the
datasheet module for each peripheral.
6.3.3 Peripheral Clock Events
Each event channel includes a peripheral clock prescaler with a range from 1 (no prescaling) to 32768. This enables
configurable periodic event generation based on the peripheral clock. It is possible to periodically trigger events in a
peripheral or to periodically trigger synchronized events in several peripherals. Since each event channel include a
prescaler, different peripherals can receive triggers with different intervals.
6.3.4 Software Events
Events can be generated from software by writing the DATA and STROBE registers. The DATA register must be written
first, since writing the STROBE register triggers the operation. The DATA and STROBE registers contain one bit for each
event channel. Bit n corresponds to event channel n. It is possible to generate events on several channels at the same
time by writing to several bit locations at once.
Software-generated events last for one clock cycle and will overwrite events from other event generators on that event
channel during that clock cycle.
Table 6-1 on page 68 shows the different events, how they can be manually generated, and how they are decoded.
Event User
Event
Routing
Network
|
Compare Match
Over-/Underflow
Error
Timer/Counter
Syncsweep
Single
Conversion
ADC
Event Generator
Event Source
Event Action
Event Action Selection