Datasheet

Functional overview STM32F091xB STM32F091xC
18/128 DocID026284 Rev 4
3.9.2 Extended interrupt/event controller (EXTI)
The extended interrupt/event controller consists of 32 edge detector lines used to generate
interrupt/event requests and wake-up the system. Each line can be independently
configured to select the trigger event (rising edge, falling edge, both) and can be masked
independently. A pending register maintains the status of the interrupt requests. The EXTI
can detect an external line with a pulse width shorter than the internal clock period. Up to 88
GPIOs can be connected to the 16 external interrupt lines.
3.10 Analog-to-digital converter (ADC)
The 12-bit analog-to-digital converter has up to 16 external and 3 internal (temperature
sensor, voltage reference, VBAT voltage measurement) channels and performs conversions
in single-shot or scan modes. In scan mode, automatic conversion is performed on a
selected group of analog inputs.
The ADC can be served by the DMA controller.
An analog watchdog feature allows very precise monitoring of the converted voltage of one,
some or all selected channels. An interrupt is generated when the converted voltage is
outside the programmed thresholds.
3.10.1 Temperature sensor
The temperature sensor (TS) generates a voltage V
SENSE
that varies linearly with
temperature.
The temperature sensor is internally connected to the ADC_IN16 input channel which is
used to convert the sensor output voltage into a digital value.
The sensor provides good linearity but it has to be calibrated to obtain good overall
accuracy of the temperature measurement. As the offset of the temperature sensor varies
from chip to chip due to process variation, the uncalibrated internal temperature sensor is
suitable for applications that detect temperature changes only.
To improve the accuracy of the temperature sensor measurement, each device is
individually factory-calibrated by ST. The temperature sensor factory calibration data are
stored by ST in the system memory area, accessible in read-only mode.
3.10.2 Internal voltage reference (V
REFINT
)
The internal voltage reference (V
REFINT
) provides a stable (bandgap) voltage output for the
ADC and comparators. V
REFINT
is internally connected to the ADC_IN17 input channel. The
Table 3. Temperature sensor calibration values
Calibration value name Description Memory address
TS_CAL1
TS ADC raw data acquired at a
temperature of 30 °C (± 5 °C),
V
DDA
= 3.3 V (± 10 mV)
0x1FFF F7B8 - 0x1FFF F7B9
TS_CAL2
TS ADC raw data acquired at a
temperature of 110 °C (± 5 °C),
V
DDA
= 3.3 V (± 10 mV)
0x1FFF F7C2 - 0x1FFF F7C3
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