User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 128
www.energymicro.com
Figure 11.1. CMU Overview
HFXO
HFRCO
LFXO
LFRCO
prescaler
CMU_HFPERCLKEN0.I2C0
HFPERCLK
TIMER1
Tim eout
Tim eout
Tim eout
Tim eout
CMU_LFACLKEN0.RTC
HFPERCLK
I2C0
CMU_HFPERCLKEN0.TIMER0
HFPERCLK
TIMER0
HFCORECLK
CM3
CMU_HFPERCLKDIV.HFPERCLKEN
CMU_HFPERCLKEN0.TIMER1
HFCLK
Clock
Gat e
Clock
Gat e
prescaler
EM0
HFCORECLK
DMA
CMU_HFCORECLKEN0.DMA
Clock
Gat e
LFACLK
RTC
CMU_LFACLKEN0.LETIMER0
Clock
Gat e
LFACLK
LETIMER0
CMU_LFACLKEN0.LCD
Clock
Gat e
LFACLK
LCD
LFACLK
CMU_LFBCLKEN0.LEUART0
Clock
Gat e
LFBCLK
LEUART0
Clock
Gat e
LFBCLK
LEUART1
LFBCLK
Clock
Gat e
Clock
Gat e
Clock
Gat e
clock
switch
clock
switch
clock
switch
prescaler
prescaler
prescaler
prescaler
prescaler
HFCORECLK
LE
CMU_HFCORECLKEN0.LE
Clock
Gat e
.
.
.
.
.
.
/2 or /4
HFCORECLK
HFPERCLK
Frame Rate Control
.
.
.
ULFRCO
PCNTnCLK
PCNTn_S0
WDOG
WDOG_CTRL.CLKSEL
CMU_LFCLKSEL.LFB / LFBE
CMU_LFCLKSEL.LFA / LFAE
CMU_LFBCLKEN0.LEUART1
CMU_LCDCTRL.FDIV
CMU_HFPERCLKDIV.HFPERCLKDIV
CMU_HFCORECLKDIV
CMU_LFBPRESC0.LEUART1
CMU_LFBPRESC0.LEUART0
CMU_LFAPRESC0.LCD
CMU_LFAPRESC0.LETIMER0
CMU_LFAPRESC0.RTC
CMU_PCNTCTRL.PCNTnCLKSEL
LFACLK
LCDpre
AUXHFRCO
Debug Trace
MSC
(Flash Programm ing)
Tim eout
AUXCLK
WDOGCLK
CMU_CMD.HFCLKSEL
.
.
.
clock
switch
CMU_CTRL_DBGCLK
CMU_LFACLKEN0.LESENSE
Clock
Gat e
LFACLK
LESENSE
prescaler
CMU_LFAPRESC0.LESENSE
LESENSE
(High frequency timing)
HFCLK
DIV
CMU_CTRL.HFCLKDIV
clock
switch
CMU_CMD.USBCCLKSEL
HFCORECLK
USBC
CMU_HFCORECLKEN0.USBC
BURTC
HFCLKNODIV
11.3.1 System Clocks
11.3.1.1 HFCLK - High Frequency Clock
HFCLK is the selected High Frequency Clock. This clock is used by the CMU and drives the two
prescalers that generate HFCORECLK and HFPERCLK. The HFCLK can be driven by a high-frequency
oscillator (HFRCO or HFXO) or one of the low-frequency oscillators (LFRCO or LFXO). By default the