RM0090 Analog-to-digital converter (ADC)
Doc ID 018909 Rev 4 290/1422
The internal temperature sensor is more suited for applications that detect temperature
variations instead of absolute temperatures. If accurate temperature reading is required, an
external temperature sensor should be used.
11.11 Battery charge monitoring
The VBATE bit in the ADC_CCR register is used to switch to the battery voltage. As the
V
BAT
voltage could be higher than V
DDA
, to ensure the correct operation of the ADC, the
V
BAT
pin is internally connected to a bridge divider.
When the VBATE is set, the bridge is automatically enabled to connect:
● VBAT/2 to the ADC1_IN18 input channel, on STM32F40xx and STM32F41xx devices
● VBAT/4 to the ADC1_IN18 input channel, on STM32F42xx and STM32F43xx devices
Note: The VBAT and temperature sensor are connected to the same ADC internal channel
(ADC1_IN18). Only one conversion, either temperature sensor or VBAT, must be selected at
a time. When both conversion are enabled simultaneously, only the VBAT conversion is
performed.
11.12 ADC interrupts
An interrupt can be produced on the end of conversion for regular and injected groups, when
the analog watchdog status bit is set and when the overrun status bit is set. Separate
interrupt enable bits are available for flexibility.
Two other flags are present in the ADC_SR register, but there is no interrupt associated with
them:
● JSTRT (Start of conversion for channels of an injected group)
● STRT (Start of conversion for channels of a regular group)
Table 53. ADC interrupts
Interrupt event Event flag Enable control bit
End of conversion of a regular group EOC EOCIE
End of conversion of an injected group JEOC JEOCIE
Analog watchdog status bit is set AWD AWDIE
Overrun OVR OVRIE
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