16.
GCLK - Generic Clock Controller
16.1. Overview
Depending on the application, peripherals may require specific clock frequencies to operate correctly. The
Generic Clock controller GCLK provides five Generic Clock Generators [4:0] that can provide a wide
range of clock frequencies.
Generators can be set to use different external and internal oscillators as source. The clock of each
Generator can be divided. The outputs from the Generators are used as sources for the Peripheral
Channels, which provide the Generic Clock (GCLK_PERIPH) to the peripheral modules, as shown in
. The number of Peripheral Clocks depends on how many peripherals the device has.
Note:
The Generator 0 is always the direct source of the GCLK_MAIN signal.
16.2. Features
•
Provides a device-defined, configurable number of Peripheral Channel clocks
•
Wide frequency range
16.3. Block Diagram
The generation of Peripheral Clock signals (GCLK_PERIPH) and the Main Clock (GCLK_MAIN) can be
seen in
.
Figure 16-1. Device Clocking Diagram
GCLK_IO
Generic Clock Generator
OSC16M
OSCCTR
Clock
Divider &
Masker
Clock
Gate
Peripheral Channel
GCLK_PERIPH
PERIPHERAL
GENERIC CLOCK CONTROLLER
MCLK
GCLK_MAIN
DFLL48M
XOSC
OSC32CTRL
OSCULP32K
XOSC32K
DPLL96M
The GCLK block diagram is shown below:
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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