Table 104. Configuring The Trigger Polarity; Figure 66. Stopping An Ongoing Conversion - STMicroelectronics STM32WL5 Series Reference Manual

RM0453
18.3.14 Stopping an ongoing conversion (ADSTP)
The software can decide to stop any ongoing conversions by setting ADSTP = 1 in the
ADC_CR register.
This resets the ADC operation and the ADC is idle, ready for a new operation.
When the ADSTP bit is set by software, any ongoing conversion is aborted and the result is
discarded (ADC_DR register is not updated with the current conversion).
The scan sequence is also aborted and reset (meaning that restarting the ADC would re-
start a new sequence).
Once this procedure is complete, the ADSTP and ADSTART bits are both cleared by
hardware and the software must wait until ADSTART=0 before starting new conversions.
ADC state
ADSTART
ADSTOP
ADC_DR
18.4 Conversion on external trigger and trigger polarity (EXTSEL,
EXTEN)
A conversion or a sequence of conversion can be triggered either by software or by an
external event (for example timer capture). If the EXTEN[1:0] control bits are not equal to
"0b00", then external events are able to trigger a conversion with the selected polarity. The
trigger selection is effective once software has set bit ADSTART = 1.
Any hardware triggers which occur while a conversion is ongoing are ignored.
If bit ADSTART = 0, any hardware triggers which occur are ignored.
Table 104
polarity.
Trigger detection disabled
Detection on rising edge
Detection on falling edge
Detection on both rising and falling edges
Note: The polarity of the external trigger can be changed only when the ADC is not converting
(ADSTART = 0).
The EXTSEL[2:0] control bits are used to select which of 8 possible events can trigger
conversions.

Figure 66. Stopping an ongoing conversion

RDY SAMPLING CH(N)
set by SW
provides the correspondence between the EXTEN[1:0] values and the trigger

Table 104. Configuring the trigger polarity

Source
CONVERTING CH(N)
DATA N-1
RM0453 Rev 5
Analog-to-digital converter (ADC)
RDY
cleared by HW
cleared by HW
set by SW
EXTEN[1:0]
00
01
10
11
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