User manual
...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 144
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Bit Name Reset Access Description
Disables the HFXO. HFXOEN has higher priority if written simultaneously. WARNING: Do not disable the HFRXO if this oscillator
is selected as the source for HFCLK.
2 HFXOEN 0 W1 HFXO Enable
Enables the HFXO.
1 HFRCODIS 0 W1 HFRCO Disable
Disables the HFRCO. HFRCOEN has higher priority if written simultaneously. WARNING: Do not disable the HFRCO if this oscillator
is selected as the source for HFCLK.
0 HFRCOEN 0 W1 HFRCO Enable
Enables the HFRCO.
11.5.10 CMU_CMD - Command Register
Offset Bit Position
0x024
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Reset
0x0
0
0
0x0
Access
W1
W1
W1
W1
Name
USBCCLKSEL
CALSTOP
CALSTART
HFCLKSEL
Bit Name Reset Access Description
31:7 Reserved
To ensure compatibility with future devices, always write bits to 0. More information in Section 2.1 (p. 3)
6:5 USBCCLKSEL 0x0 W1 USB Core Clock Select
Selects the clock for HFCORECLK
USBC
. The status register is updated when the clock switch has taken effect.
Value Mode Description
1 HFCLKNODIV Select HFCLKNODIV as HFCORECLK
USBC
2 LFXO Select LFXO as HFCORECLK
USBC
3 LFRCO Select LFRCO as HFCORECLK
USBC
4 CALSTOP 0 W1 Calibration Stop
Stops the calibration counters.
3 CALSTART 0 W1 Calibration Start
Starts the calibration, effectively loading the CMU_CALCNT into the down-counter and start decrementing.
2:0 HFCLKSEL 0x0 W1 HFCLK Select
Selects the clock source for HFCLK. Note that selecting an oscillator that is disabled will cause the system clock to stop. Check the
status register and confirm that oscillator is ready before switching.
Value Mode Description
1 HFRCO Select HFRCO as HFCLK
2 HFXO Select HFXO as HFCLK
3 LFRCO Select LFRCO as HFCLK
4 LFXO Select LFXO as HFCLK