AN3023

ADC hardware description

Doc ID 16113 Rev 1

3/23

1

ADC hardware description

1.1

General properties

STM8A family microcontrollers include an analog-to-digital converter which has up to 16

multiplexed inputs. The ADC resolution is 10 bits. The number of external analog inputs

depends on the package size of the particular STM8A family device.

The ADC is a successive approximation analog-to-digital converter. Conversion can be

performed in continuous mode or single mode. The digital result is then stored in registers.

Because the ADC resolution is 10 bits and the ADC data register length is 16 bits, the

analog-to-digital converter result is stored in two 8-bit registers, and the data is either right

or left aligned (this is selectable).

The event used to start conversion can be generated by software or by the STM8A

start of A/D conversion can also be triggered by an external pin.

The reference voltage for the analog-to-digital converter depends on the package. It comes

either from an external source—in this case the reference must be connected to two

external pins—or is connected internally to analog power supply pins. The value of this

reference voltage is limited to within the range from 2.75 V up to the voltage applied on the

increased by so-called analog zooming—using a smaller reference voltage around the

range of values to be measured.

If needed, an interrupt can be generated at the end of conversion and if an analog watchdog

event occurred.

The analog-to-digital converter is driven by a clock derived from the MCU master clock

through a programmable divider. This allows you to select the ADC clock speed according to

your application requirements.

a.

Trigger feature available on selected devices