Analog-to-digital converter (ADC) RM0401
224/771 RM0401 Rev 3
11.6 Conversion on external trigger and trigger polarity
Conversion can be triggered by an external event (e.g. timer capture, EXTI line). If the
EXTEN[1:0] control bits (for a regular conversion) or JEXTEN[1:0] bits (for an injected
conversion) are different from “0b00”, then external events are able to trigger a conversion
with the selected polarity. Table 44 provides the correspondence between the EXTEN[1:0]
and JEXTEN[1:0] values and the trigger polarity.
Note: The polarity of the external trigger can be changed on the fly.
The EXTSEL[3:0] and JEXTSEL[3:0] control bits are used to select which out of 16 possible
events can trigger conversion for the regular and injected groups.
Table 45 gives the possible external trigger for regular conversion.
Table 44. Configuring the trigger polarity
Source EXTEN[1:0] / JEXTEN[1:0]
Trigger detection disabled 00
Detection on the rising edge 01
Detection on the falling edge 10
Detection on both the rising and falling edges 11
Table 45. External trigger for regular channels
Source Type EXTSEL[3:0]
TIM1_CH1 event
Internal signal from on-chip
timers
0000
TIM1_CH2 event 0001
TIM1_CH3 event 0010
TIM5_CH1 event 1010
TIM5_CH2 event 1011
TIM5_CH3 event 1100
Not used 1101
Not used 1110
EXTI line11 External pin 1111
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