Atmel SAM4L Xplained Pro Starter Kit Atmel ATSAM4L-XSTK ATSAM4L-XSTK 데이터 시트
제품 코드
ATSAM4L-XSTK
452
42023E–SAM–07/2013
ATSAM4L8/L4/L2
19.3
Block Diagram
Figure 19-1. Asynchronous Timer Block Diagram
19.4
Product Dependencies
In order to use this module, other parts of the system must be configured correctly, as described
below.
below.
19.4.1
Power Management
When the AST is enabled, it will remain clocked as long as its selected clock source is running. It
can also wake the CPU from the currently active sleep mode. Refer to
can also wake the CPU from the currently active sleep mode. Refer to
for details on the different sleep modes.
19.4.2
Clocks
The clock for the AST bus interface (CLK_AST) is generated by the Power Manager. This clock
is turned on by default, and can be enabled and disabled in the Power Manager.
is turned on by default, and can be enabled and disabled in the Power Manager.
A number of clocks can be selected as source for the internal prescaler clock CLK_AST_PRSC.
The prescaler, counter, and interrupt will function as long as this selected clock source is active.
The selected clock must be enabled in the System Control Interface (SCIF).
The prescaler, counter, and interrupt will function as long as this selected clock source is active.
The selected clock must be enabled in the System Control Interface (SCIF).
The following clock sources are available:
• System RC oscillator (RCSYS oscillator). This oscillator is always enabled, except in some
sleep modes. Refer to
for the
characteristic frequency of this oscillator.
• 32kHz clock (OSC32 or RC32). The oscillator must be enabled before use. Selection
between OSC32 and RC32 is done inside the Backup Power Manager module.
32-bit
Prescaler
32-bit
Counter
Alarm
Interrupts
COUNTER
VALUE
CLK_AST_CNT
OVF
CONTROL
REGISTER
EN
CSSEL
PSEL
Periodic
Interrupts
ALARM
REGISTER
Interrupt
Status
and
Control
IRQs
PERIODIC
INTERVAL
INTERVAL
REGISTER
Events
Wake
Control
Wake
WAKE ENABLE
REGISTER
DIGITAL
TUNER
REGISTER
RCSYS
OSC32
APB clock
GCLK
others
CLK_AST
CLK_AST_PRSC
CLK_AST
CLK_AST