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RM0444 Rev 5 353/1390

RM0444 Analog-to-digital converter (ADC)

403

15.3.7 Configuring the ADC

Software must write to the ADCAL and ADEN bits in the ADC_CR register if the ADC is

disabled (ADEN must be 0).

Software must only write to the ADSTART and ADDIS bits in the ADC_CR register only if

the ADC is enabled and there is no pending request to disable the ADC (ADEN = 1 and

ADDIS = 0).

For all the other control bits in the ADC_IER, ADC_CFGRi, ADC_SMPR, ADC_CHSELR

and ADC_CCR registers, refer to the description of the corresponding control bit in

Section 15.12: ADC registers.

ADC_AWDTRx registers can be modified when conversion is ongoing.

Software must only write to the ADSTP bit in the ADC_CR register if the ADC is enabled

(and possibly converting) and there is no pending request to disable the ADC (ADSTART =

1 and ADDIS = 0).

Note: There is no hardware protection preventing software from making write operations forbidden

by the above rules. If such a forbidden write access occurs, the ADC may enter an

undefined state. To recover correct operation in this case, the ADC must be disabled (clear

ADEN

= 0 and all the bits in the ADC_CR register).

15.3.8 Channel selection (CHSEL, SCANDIR, CHSELRMOD)

There are up to 19 multiplexed channels:

• 16 analog inputs from GPIO pins (ADC_INx)

• 3 internal analog inputs (Temperature Sensor, Internal Reference Voltage, V

BAT

channel)

It is possible to convert a single channel or a sequence of channels.

The sequence of the channels to be converted can be programmed in the ADC_CHSELR

channel selection register: each analog input channel has a dedicated selection bit

(CHSELx).

The ADC scan sequencer can be used in two different modes:

• Sequencer not fully configurable:

The order in which the channels are scanned is defined by the channel number

(CHSELRMOD bit must be cleared in ADC_CFGR1 register):

– Sequence length configured through CHSELx bits in ADC_CHSELR register

– Sequence direction: the channels are scanned in a forward direction (from the

lowest to the highest channel number) or backward direction (from the highest to

the lowest channel number) depending on the value of SCANDIR bit

(SCANDIR = 0: forward scan, SCANDIR = 1: backward scan)

ST STM32G0 1 Series User Manual

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