AN3139 datasheet(30/63 Pages) STMICROELECTRONICS

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Block-by-block compatibility analysis

AN3139

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circuits. Up to two VDDIO / VSSIO pin pairs are used as well as the main VDD / VSS digital

supply pair, depending on the pin-count:

●

Both VDDIO pairs are present in the 48-pin package in the STM8L15x/STM8L16x sub-

family.

●

Only one VDDIO pin is available to supply power to the I/Os in the STM8L10x and

STM8L15x/STM8L16x sub-families from 32-pin packages to 20-pin packages.

The total output current is limited by the number of supply pins. The total output current

capability declines for smaller packages, regardless of the number of I/Os with high-sink

capability.

In the medium, medium+ and high density STM8L15x/STM8L16x devices,, the VLCD pin for

connecting the external voltage source for the LCD is present on the 48-pin and 32-pin

packages when the LCD is available.

3.1.2

ADC power supply and voltage reference

The analog power supply design includes an extra power supply for the analog parts of the

microcontroller and an external reference voltage connected via an extra pin pair.

●

The VDDA/VSSA and the VREF+/VREF- analog supply pin pair are present on the 28-pin

and 48-pin packages in the STM8L15x/STM8L16x sub-family. Without these pins, it is

not possible to use the ADC zooming function feature (see Section 3.4: ADC modes for

more details).

●

For the rest of the STM8L15x/STM8L16x sub-family (32-pin package) the ADC

reference is taken from the main analog supply VDDA.

Note:

As the ADC is not present in the STM8L10x family, VDDA/VSSA and VREF+/VREF analog

supply pins are not available on packages for this family.

3.1.3

Alternate functions

The main purpose of the alternate feature concept is to keep the microcontroller

configurable for different user and application needs. This is especially important and useful

in low pin-count packages.

Default alternate functions can be enabled on dedicated pins by settings in the peripheral

registers.

In the STM8L15x/STM8L16x sub-family, a large number of alternate functions can be

remapped to other pins by programming the system configuration controller registers.

Consequently, many functions that would otherwise be lost by migrating to a smaller

package size are preserved by remapping alternate functions to the remaining pins. For

more details on pinout and packages, please refer to the related datasheet.

3.2

GPIO and peripheral registers

3.2.1

Mapping overview

The space for the GPIO and peripheral registers is mapped in the memory area between

addresses 0x5000 and 0x57FF. The register blocks for each peripheral available in the sub-

family have the same start addresses and the same register names.

AN3139 Datasheet(PDF) 30 Page - STMicroelectronics

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