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GD32L23x User Manual
205
4.
Set CLB=1;
5.
Wait for CLB =0.
13.4.2.
Dual clock domain architecture
The ADC sub-module, with exception of the APB interface block, is feed by an ADC clock,
which can be asynchronous and independent from the APB clock.
Application can reduce PLCK frequency for low power operation while still keeping optimum
ADC performance.
for more information on generating this clock source.
13.4.3.
ADCON switch
The ADC module is enabled or disabled by configuring the ADCON bit in the ADC_CTL1
register. The ADC module will keep in reset state if this bit is 0. For power saving, when this
bit is 0, the analog sub-module will be enter power-down mode. After ADC is enabled, you
need delay t
SU
time for sampling, the value of t
SU
please refer to the device datasheet.
Note:
When the ADC uses the internal reference VREF (VREFEN = 1), ensure the VREFDY
bit in SYSCFG_VREF_CS register is set before the ADC is enabled.
13.4.4.
Regular and inserted channel groups
The ADC supports 20 multiplexed channels and organizes the conversion results into two
groups: a regular channel group and an inserted channel group.
In the regular group, a sequence of up to 16 conversions can be organized in a specific
sequence. The ADC_RSQ0~ADC_RSQ2 registers specify the selected channels of the
regular group. The RL[3:0] bits in the ADC_RSQ0 register specify the total conversion
sequence length.
In the inserted group, a sequence of up to 4 conversions can be organized in a specific
sequence. The ADC_ISQ register specifies the selected channels of the inserted group. The
IL[1:0] bits in the ADC_ISQ register specify the total conversion sequence length.
13.4.5.
Conversion modes
Single conversion mode
This mode can be used in both regular and inserted channel groups. In the single conversion
mode, the ADC performs conversion on the channel specified in the RSQ0[4:0] bits in
ADC_RSQ2 or the channel specified in the ISQ3[4:0] bits in ADC_ISQ. When the ADCON is
1, the ADC samples and converts a single channel, once the corresponding software trigger
or external trigger is active.