15.
Clock System
This chapter summarizes the clock distribution and terminology in the SAM L22 device. It will not explain
every detail of its configuration. For in-depth documentation, see the respective peripherals descriptions
and the
Generic Clock
documentation.
Related Links
on page 141
GCLK - Generic Clock Controller
on page 121
15.1. Clock Distribution
Figure 15-1. Clock Distribution
GCLK
Generator 0
OSCCTRL
GCLK
GCLK Generator 1
GCLK Generator x
Peripheral Channel 0
(DFLL48M Reference)
Peripheral Channel 1
(FDPLL96M Reference)
Peripheral z
Peripheral 0
Syncronous Clock
Controller
MCLK
AHB/APB System Clocks
GCLK_MAIN
OSC16M
DFLL48M
XOSC
Generic
Clocks
OSCK32CTRL
OSCULP32K
XOSC32K
FDPLL96M
Peripheral Channel 3
GCLK_DFLL48M_REF
GCLK_DPLL
Peripheral Channel y
GCLK_DPLL_32K
GCLK_DPLL
GCLK_DPLL_32K
RTC
CLK_RTC_OSC
CLK_WDT_OSC
Peripheral Channel 2
(FDPLL96M Reference)
WDT
32kHz
1kHz
32kHz
1kHz
CLK_ULP32K
EIC
SLCD
CLK_SLCD_OSC
The SAM L22 clock system consists of:
•
Clock sources
, controlled by OSCCTRL and OSC32KCTRL
–
A clock source provides a time base that is used by other components, such as Generic
Clock Generators. Example clock sources are the internal 16MHz oscillator (OSC16M),
external crystal oscillator (XOSC) and the Digital Frequency Locked Loop (DFLL48M).
•
Generic Clock Controller (GCLK),
which generates, controls and distributes the asynchronous clock
consisting of:
–
Generic Clock Generators:
These are programmable prescalers that can use any of the
system clock sources as a time base. The Generic Clock Generator 0 generates the clock
signal GCLK_MAIN, which is used by the Power Manager and the Main Clock (MCLK)
module, which in turn generates synchronous clocks.
–
Generic Clocks:
These are clock signals generated by Generic Clock Generators and output
by the Peripheral Channels, and serve as clocks for the peripherals of the system. Multiple
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
115