GD32W51x User Manual
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channel digital filter respectively. In addition, as long as the input channel is enabled, the input
channel will immediately start receiving serial data.
HPDF can enter stop mode by clearing FLTEN during operation. After entering stop mode,
the ongoing conversion tasks of the HPDF module will immediately stop, and the configuration
of the registers remains unchanged (except for the HPDF_FLTySTAT and
HPDF_FLTyTMSTAT registers are reset).
In stop mode, the HPDF system clock will automatically stop. The HPDFEN bit must be
cleared before the system clock is stopped to enter stop mode.
Low power mode
HPDF module optimizes the reduction of power consumption. In the normal working mode,
the filter and integrator will automatically enter the idle state to achieve the purpose of
reducing power consumption when there is no conversion task.
30.3.3.
HPDF clock
The clock of HPDF includes the system clock and the serial clock. The system clock is used
to drive the internal modules, and the serial clock used by the serial interface.
System clock
The system clock f
HPDFCLK
of HPDF is used to drive channel transceiver, digital filter, integrator,
threshold monitor, malfunction monitor, extremum detector and control module. The HPDF
system clock source can be configured by the HPDFSEL bit in the ADDCTL register of the
RCU chapter.
Serial input clock
The serial interface of HPDF can receive clock signal from external sigma delta modulator by
CKINx pin, so as to receive the serial data stream from sigma delta modulator.
Using external input clock in serial interface is limited by clock frequency. If the standard SPI
interface is used, the system clock f
HPDFCLK
≥ 4f
CKIN
. If the Manchester coding interface is used,
the system clock f
HPDFCLK
≥ 6f
CKIN
is required.
Serial output clock
HPDF supports the function of outputting serial clock, which can drive sigma delta modulator
connected with it. The source of the serial output clock can be selected by CKOUTSEL bit in
HPDF_CH0CTL register. When CKOUTSEL=0, the serial output clock source is the HPDF
system clock. When CKOUTSEL=1, the serial output clock source is the audio clock. And the
configuration of the audio clock can refer to the HPDFAUDIOSEL[1:0] bit field in the ADDCTL
register of the RCU chapter.