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GD32L23x User Manual
213
the SPTn [2:0] bits in the ADC_SAMPT0 and ADC_SAMPT1 registers. Different sampling
time can be specified for each channel. For 12-bit resolution, the total conversion time is
“sampling time + 12.5” ADCCLK cycles.
Example:
ADCCLK = 16MHz and sampling time is 2.5 cycles, the total conversion time is
“2.5+12.5”
ADCCLK cycles, that means 0.9375us.
13.4.10.
External trigger
The conversion of regular or inserted group can be triggered by rising edge of external trigger
inputs. The external trigger source of regular channel group is controlled by the ETSRC [2:0]
bits in the ADC_CTL1 register, while the external trigger source of inserted channel group is
controlled by the ETSIC [2:0] bits in the ADC_CTL1 register
ETSRC [2:0] and ETSIC [2:0]control bits are used to specify which out of 8 possible events
can trigger conversion for the regular and inserted groups.
Table 13-3. External trigger for regular channels of ADC
ETSRC[2:0]
Trigger source
Trigger type
000
TIMER8_CH0
Internal on-chip signal
001
TIMER8_CH1
010
reserved
011
TIMER1_CH1
100
TIMER2_TRGO
101
TIMER11_CH0
110
EXTI_11
External signal
111
SWRCST
Software trigger
Table 13-4. External trigger for inserted channels of ADC
ETSIC[2:0]
Trigger source
Trigger type
000
reserved
Internal on-chip signal
001
reserved
010
TIMER1_TRGO
011
TIMER1_CH0
100
TIMER2_CH3
101
reserved
110
EXTI_15
External signal
111
SWICST
Software trigger
13.4.11.
DMA request
The DMA request, which is enabled by the DMA bit in ADC_CTL1 register, is used to transfer
data of regular group for conversion of more than one channel. The ADC generates a DMA