ST STM32F102 Series Reference Manual page 173

RM0008
Bit 20 EXTTRIG: External Trigger Conversion mode for regular channels
This bit is set and cleared by software to enable/disable the external trigger used to start conversion
of a regular channel group.
0: Conversion on external event disabled
1: Conversion on external event enabled
Bits 19:17 EXTSEL[2:0]: External event select for regular group
These bits select the external event used to trigger the start of conversion of a regular group:
For ADC1 and ADC2, the assigned triggers are:
000: Timer 1 CC1 event
001: Timer 1 CC2 event
010: Timer 1 CC3 event
011: Timer 2 CC2 event
100: Timer 3 TRGO event
101: Timer 4 CC4 event
110: EXTI line11/TIM8_TRGO event (TIM8_TRGO is available only in high-density devices)
111: SWSTART
For ADC3, the assigned triggers are:
000: Timer 3 CC1 event
001: Timer 2 CC3 event
010: Timer 1 CC3 event
011: Timer 8 CC1 event
100: Timer 8 TRGO event
101: Timer 5 CC1 event
110: Timer 5 CC3 event
111: SWSTART
Bit 16 Reserved, must be kept cleared.
Bit 15 JEXTTRIG: External trigger conversion mode for injected channels
This bit is set and cleared by software to enable/disable the external trigger used to start conversion
of an injected channel group.
0: Conversion on external event disabled
1: Conversion on external event enabled
Analog-to-digital converter (ADC)
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