data loss may result during debugging. This peripheral can be forced to halt operation during debugging -
refer to the Debug Control (DBGCTRL) register for details.
30.5.8. Register Access Protection
Registers with write-access can be optionally write-protected by the Peripheral Access Controller (PAC),
except the following:
•
Channel Status (CHSTATUS)
•
Interrupt Flag Status and Clear register (INTFLAG)
Note:
Optional write-protection is indicated by the "PAC Write-Protection" property in the register
description.
When the CPU is halted in debug mode, all write-protection is automatically disabled. Write-protection
does not apply for accesses through an external debugger.
30.5.9. Analog Connections
Not applicable.
30.6. Functional Description
30.6.1. Principle of Operation
The Event System consists of several channels which route the internal events from peripherals
(generators) to other internal peripherals or IO pins (users). Each event generator can be selected as
source for multiple channels, but a channel cannot be set to use multiple event generators at the same
time.
A channel path can be configured in asynchronous, synchronous or re-synchronized mode of operation.
The mode of operation must be selected based on the requirements of the application.
When using synchronous or resynchronized path, the Event System includes options to transfer events to
users when rising, falling or both edges are detected on on event generators.
For further details, refer to “
” of this chapter.
30.6.2. Basic Operation
30.6.2.1. Initialization
Before enabling events routing within the system, the Event Users Multiplexer and Event Channels must
be configured. The Event Users Multiplexer must be configured first.
For further details about the event user multiplexer configuration, refer to “
For further details about the event channels configuration, refer to “
30.6.2.2. Enabling, Disabling, and Resetting
The EVSYS is always enabled.
The EVSYS is reset by writing a ‘1’ to the Software Reset bit in the Control A register (CTRLA.SWRST).
All registers in the EVSYS will be reset to their initial state and all ongoing events will be canceled.
.SWRST register for details.
30.6.2.3. User Multiplexer Setup
The user multiplexer defines the channel to be connected to which event user. Each user multiplexer is
dedicated to one event user. A user multiplexer receives all event channels output and must be
Atmel SAM L22G / L22J / L22N [DATASHEET]
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