Datasheet

Functional overview STM32F21xxx
36/175 DocID17050 Rev 9
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.
The events generated by the timers TIM1, TIM2, TIM3, TIM4, TIM5 and TIM8 can be
internally connected to the ADC start trigger and injection trigger, respectively, to allow the
application to synchronize A/D conversion and timers.
3.35 DAC (digital-to-analog converter)
The two 12-bit buffered DAC channels can be used to convert two digital signals into two
analog voltage signal outputs. The design structure is composed of integrated resistor
strings and an amplifier in inverting configuration.
This dual digital Interface supports the following features:
• two DAC converters: one for each output channel
• 8-bit or 12-bit monotonic output
• left or right data alignment in 12-bit mode
• synchronized update capability
• noise-wave generation
• triangular-wave generation
• dual DAC channel independent or simultaneous conversions
• DMA capability for each channel
• external triggers for conversion
• input voltage reference V
REF+
Eight DAC trigger inputs are used in the device. The DAC channels are triggered through
the timer update outputs that are also connected to different DMA streams.
3.36 Temperature sensor
The temperature sensor has to generate a voltage that varies linearly with temperature. The
conversion range is between 1.8 and 3.6 V. The temperature sensor is internally connected
to the ADC1_IN16 input channel which is used to convert the sensor output voltage into a
digital value.
As the offset of the temperature sensor varies from chip to chip due to process variation, the
internal temperature sensor is mainly suitable for applications that detect temperature
changes instead of absolute temperatures. If an accurate temperature reading is needed,
then an external temperature sensor part should be used.
3.37 Serial wire JTAG debug port (SWJ-DP)
The ARM SWJ-DP interface is embedded, and is a combined JTAG and serial wire debug
port that enables either a serial wire debug or a JTAG probe to be connected to the target.
The JTAG TMS and TCK pins are shared with SWDIO and SWCLK, respectively, and a
specific sequence on the TMS pin is used to switch between JTAG-DP and SW-DP.