STM32W108C8

Analog-to-digital converter
STM32W108C8
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:
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11.1.2 GPIO usage
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.
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 GPIO_PnCFGH/L register. Note that a GPIO
pin in analog mode cannot be used for any digital functions, and software always reads it as
1.
Table 106.
ADC GPIO pin usage
See Section 8: General-purpose input/outputs on page 55 for more information about how
to configure the GPIO pins.
11.1.3 Voltage reference
Analog Signal GPIO Configuration control
ADC0 input PB5 GPIO_PBCFGH[7:4]
ADC1 input PB6 GPIO_PBCFGH[11:8]
ADC2 input PB7 GPIO_PBCFGH[15:12]
ADC3 input PC1 GPIO_PCCFGH[7:4]
ADC4 input PA4 GPIO_PACFGH[3:0]
ADC5 input PA5 GPIO_PACFGH[7:4]
VREF input or output PB0 GPIO_PBCFGH[3:0]
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
GPIO_PBCFGH[3:0]. See the STM32W108C8 HAL documentation for more information on
the system functions required to use an external reference.
161/215 Doc ID 018587 Rev 2