GD32W51x User Manual
367
Figure 14-9. Data alignment of 12-bit resolution
Sign Sign Sign Sign
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
Regular group data
Inserted group data
0
0
0
Sign
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
Regular group data
Inserted group data
DAL=0
DAL=1
14.4.8.
Programmable sampling time
The number of ADC_CLK cycles which is used to sample the input voltage can be specified
by the SPTn[2:0] bits in the ADC_SAMPT0 and ADC_SAMPT1 registers. And each channel
can specify different sampling times. For 12-bit resolution, the total conversion time is
“sampling time + 12.5” ADCCLK cycles.
Example:
ADCCLK = 35MHz and sample time is 1.5 cycles, the total conversion time is “1.5+12.5”
ADCCLK cycles, that means 0.4us.
14.4.9.
External trigger
The conversion of regular or inserted group can be triggered by rising/ falling edge of external
trigger inputs. The ETMRC[1:0] and ETMIC[1:0] bits in the ADC_CTL1 register control the
trigger modes of regular and inserted group respectively. The external trigger source of
regular channel group is controlled by the ETSRC[3:0] bits in the ADC_CTL1 register, while
the external trigger source of inserted channel group is controlled by the ETSIC[3:0] bits in
the ADC_CTL1 register
The ETSRC[3:0] and ETSIC[3:0]control bits are used to specify which one can trigger
conversion for the regular and inserted groups.
Table 14-3. External trigger modes
ETMRC[1:0]/ ETMIC[1:0]
Trigger m ode
00
External trigger disable
01
Rising edge of external trigger enable
10
Falling edge of external trigger enable
11
Rising and falling edge of external trigger enable