...the world's most energy friendly microcontrollers
2014-07-02 - Gecko Family - d0001_Rev1.30
105
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Bit
Name
Reset
Access
Description
Value
Mode
Description
0
XTAL
32.768 kHz crystal oscillator.
1
BUFEXTCLK
An AC coupled buffer is coupled in series with LFXTAL_N pin, suitable for external
sinus wave (32.768 kHz).
2
DIGEXTCLK
Digital external clock on LFXTAL_N pin. Oscillator is effectively bypassed.
10:9
HFXOTIMEOUT
0x3
RW
HFXO Timeout
Configures the start-up delay for HFXO.
Value
Mode
Description
0
8CYCLES
Timeout period of 8 cycles.
1
256CYCLES
Timeout period of 256 cycles.
2
1KCYCLES
Timeout period of 1024 cycles.
3
16KCYCLES
Timeout period of 16384 cycles.
8
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in Section 2.1 (p. 3)
7
HFXOGLITCHDETEN
0
RW
HFXO Glitch Detector Enable
This bit enables the glitch detector which is active as long as the start-up ripple-counter is counting. A detected glitch will reset the
ripple-counter effectively increasing the start-up time. Once the ripple-counter has timed-out, glitches will not be detected.
6:5
HFXOBUFCUR
0x1
RW
HFXO Boost Buffer Current
This value has been set during calibration and should not be changed.
4
Reserved
To ensure compatibility with future devices, always write bits to 0. More information in Section 2.1 (p. 3)
3:2
HFXOBOOST
0x3
RW
HFXO Start-up Boost Current
Used to adjust start-up boost current for HFXO.
Value
Mode
Description
0
50PCENT
50 %.
1
70PCENT
70 %.
2
80PCENT
80 %.
3
100PCENT
100 % (default).
1:0
HFXOMODE
0x0
RW
HFXO Mode
Set this to configure the external source for the HFXO. The oscillator setting takes effect when 1 is written to HFXOEN in
CMU_OSCENCMD. The oscillator setting is reset to default when 1 is written to HFXODIS in CMU_OSCENCMD.
Value
Mode
Description
0
XTAL
4-32 MHz crystal oscillator.
1
BUFEXTCLK
An AC coupled buffer is coupled in series with HFXTAL_N, suitable for external sine
wave (4-32 MHz). The sine wave should have a minimum of 200 mV peak to peak.
2
DIGEXTCLK
Digital external clock on HFXTAL_N pin. Oscillator is effectively bypassed.
11.5.2 CMU_HFCORECLKDIV - High Frequency Core Clock Division
Register
Offset
Bit Position
0x004
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
Access
RW
Name
Summary of Contents for EFM32G
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