STM32WL55JC datasheet(40/145 Pages) STMICROELECTRONICS

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Functional overview

STM32WL55/54xx

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DS13293 Rev 1

3.19

Cyclic redundancy check (CRC)

The CRC calculation unit is used to get a CRC code from 8-, 16- or 32-bit data word and a

generator polynomial.

Among other applications, CRC-based techniques are used to verify data transmission or

storage integrity. In the scope of the functional safety standards, they offer a means of

verifying the Flash memory integrity. The CRC calculation unit helps to compute a signature

of he software during runtime, to be compared with a reference signature generated at link

time and stored at a given memory location.

3.20

Analog-to-digital converter (ADC)

A native 12-bit ADC is embedded into the devices. It can be extended to 16-bit resolution

through hardware oversampling. The ADC has up to 12 external channels and four internal

channels (temperature sensor, voltage reference, VBAT(a) monitoring, DAC output). The

ADC performs conversions in single-shot or scan mode. In scan mode, automatic

conversion is performed on a selected group of analog inputs.

The ADC frequency is independent from the CPU1/2 frequency, allowing maximum

sampling rate of ~2 Msps even with a low CPU speed. An auto-shutdown function

guarantees that the ADC is powered off except during the active conversion phase.

The ADC can be served by the DMA controller. It can operate in the whole VDD supply

range.

The ADC features a hardware oversampler up to 256 samples, improving the resolution to

16 bits. Refer to the application note Improving STM32F1 Series, STM32F3 Series and

STM32Lx Series ADC resolution by oversampling (AN2668).

An analog watchdog feature allows very precise monitoring of the converted voltage of one,

some or all scanned channels. An interrupt is generated when the converted voltage is

outside the programmed thresholds.

The events generated by the general-purpose timers (TIMx) can be internally connected to

the ADC start triggers, to allow the application to synchronize A/D conversions with timers.

3.20.1

Temperature sensor

The temperature sensor (TS) generates a VTS voltage that varies linearly with temperature.

The temperature sensor is internally connected to the ADC VIN[12] input channel, 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 may

vary from part to part due to process variation, the uncalibrated internal temperature sensor

is suitable only for relative temperature measurements.

To improve the accuracy of the temperature sensor, each part is individually factory-

calibrated by ST. The resulting calibration data is stored in the device engineering bytes,

accessible in read-only mode.

a. VDD on STM32WL55/54UxYx devices.

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