STM32W108HB datasheet(219/278 Pages) STMICROELECTRONICS

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STM32W108HB STM32W108CC STM32W108CB STM32W108CZ

Analog-to-digital converter

Doc ID 16252 Rev 14

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11.1

Functional description

11.1.1

Setup and configuration

To use the ADC follow this procedure, described in more detail in the next sections:

●

Configure any GPIO pins to be used by the ADC in analog mode.

●

Configure the voltage reference (internal or external).

●

Set the offset and gain values.

●

Reset the ADC DMA, define the DMA buffer, and start the DMA in the proper transfer

mode.

●

If interrupts will be used, configure the primary ADC interrupt and specific mask bits.

●

Write the ADC configuration register to define the inputs, voltage range, sample time,

and start the conversions.

11.1.2

GPIO usage

A GPIO pin used by the ADC as an input or voltage reference must be configured in analog

mode by writing 0 to its 4-bit field in the proper GPIOx_CRH/L register. Note that a GPIO pin

in analog mode cannot be used for any digital functions, and software always reads it as 1.

ADC0 input

GPIOB_CRH[7:4]

ADC1 input

GPIOB_CRH[11:8]

ADC2 input

GPIOB_CRH[15:12]

ADC3 input

GPIOC_CRH[7:4]

ADC4 input

GPIOA_CRH[3:0]

ADC5 input

GPIOA_CRH[7:4]

VREF input or output

GPIOB_CRH[3:0]

See Section 8: General-purpose input/output on page 87 for more information about how to

configure the GPIO pins.

11.1.3

Voltage reference

The ADC voltage reference (VREF), may be internally generated or externally sourced from

PB0. If internally generated, it may optionally be output on PB0.

To use an external reference, an ST system function must be called after reset and after

waking from deep sleep. PB0 must also be configured in analog mode using

GPIOB_CRH[3:0]. See the STM32W108 HAL documentation for more information on the

system functions required to use an external reference.

Table 37.

ADC GPIO pin usage

Analog Signal

GPIO

Configuration control

PB5

PB6

PB7

PC1

PA4

PA5

PB0

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