Buffered Mode - Silicon Laboratories EFR32xG21 Wireless Gecko Reference Manual
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18.12.4 BUFFERED Mode
In BUFFERED Mode LETIMERn_TOPBUFF and LETIMERn_REP1 registers are used as Buffers for LETIMERn_TOP and LETI-
MERn_REP0 respectiverly. If both LETIMERn_TOP and LETIMERn_REP0 are 0 in buffered mode, and CNTTOPEN and BUFTOP in
LETIMERn_CTRL are set, the values of LETIMERn_TOPBUFF and LETIMERn_REP1 are loaded into LETIMERn_TOP and LETI-
MERn_REP0 respectively when the timer is started. If no additional writes to LETIMERn_REP1 are done before the timer stops, LETI-
MERn_REP1 determines the number of pulses/toggles generated on the output, and LETIMERn_TOPBUFF determines the period
lengths.
As the RTCC can also be used via PRS to start the LETIMER, the RTCC and LETIMER can thus be combined to generate specific
pulse-trains at given intervals. Software can update LETIMERn_TOPBUFF and LETIMERn_REP1 to change the number of pulses and
pulse-period in each train, but if changes are not required, software does not have to update the registers between each pulse train.
For the example in
Figure 18.11 LETIMER - Buffered Mode Waveform on page
two pulses with 3 cycle periods, or a single pulse 3 cycles wide every time the LETIMER is started. After the output has been gener-
ated, the LETIMER stops, and is ready to be triggered again.
Initial configuration,
REP1 just written
TOP1
TOP0
CNT
REP0
REP1
Int. flags set
LFACLK
LETIMERn
LETn_O0
UFOA0 = 01
LETn_O1
UFOA0 = 10
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Stop
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X
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0
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0
0
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u
u
u
u
u
u
u
UFIF
UFIF
REP0IF
Figure 18.11. LETIMER - Buffered Mode Waveform
410, the initial values cause the LETIMER to generate
Write
START=1
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u
u
u
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u
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u
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u
UFIF
REP0IF
Reference Manual
LETIMER - Low Energy Timer
Write
START=1
Stop
2
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0
0
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0
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0
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2
u
u
u
u
u
u
u
UFIF
UFIF
Rev. 0.4 | 410
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