Analog-to-digital converter (ADC) RM0390
360/1328 RM0390 Rev 4
13.3.3 ADC clock
The ADC features two clock schemes:
• Clock for the analog circuitry: ADCCLK, common to all ADCs
This clock is generated from the APB2 clock divided by a programmable prescaler that
allows the ADC to work at f
PCLK2
/2, /4, /6 or /8. Refer to the datasheets for the
maximum value of ADCCLK.
• Clock for the digital interface (used for registers read/write access)
This clock is equal to the APB2 clock. The digital interface clock can be
enabled/disabled individually for each ADC through the RCC APB2 peripheral clock
enable register (RCC_APB2ENR).
13.3.4 Channel selection
There are 16 multiplexed channels. It is possible to organize the conversions in two groups:
regular and injected. A group consists of a sequence of conversions that can be done on
any channel and in any order. For instance, it is possible to implement the conversion
sequence in the following order: ADC_IN3, ADC_IN8, ADC_IN2, ADC_IN2, ADC_IN0,
ADC_IN2, ADC_IN2, ADC_IN15.
• A regular group is composed of up to 16 conversions. The regular channels and their
order in the conversion sequence must be selected in the ADC_SQRx registers. The
total number of conversions in the regular group must be written in the L[3:0] bits in the
ADC_SQR1 register.
• An injected group is composed of up to 4 conversions. The injected channels and
their order in the conversion sequence must be selected in the ADC_JSQR register.
The total number of conversions in the injected group must be written in the L[1:0] bits
in the ADC_JSQR register.
If the ADC_SQRx or ADC_JSQR registers are modified during a conversion, the current
conversion is reset and a new start pulse is sent to the ADC to convert the newly chosen
group.
Temperature sensor, V
REFINT
and V
BAT
internal channels
• The temperature sensor is internally connected to ADC1_IN18 channel which is shared
with VBAT. Only one conversion, temperature sensor or VBAT, must be selected at a
time. When the temperature sensor and VBAT conversion are set simultaneously, only
the VBAT conversion is performed.
The internal reference voltage VREFINT is connected to ADC1_IN17.
The V
BAT
channel is connected to ADC1_IN18 channel. It can also be converted as an
injected or regular channel.
Note: The temperature sensor, V
REFINT
and the V
BAT
channel are available only on the master
ADC1 peripheral.
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