AN3422 datasheet(29/52 Pages) STMICROELECTRONICS

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AN3422

Peripheral migration

Doc ID 018976 Rev 2

29/52

4.7

GPIO

The STM32L1 GPIO peripheral embeds new features compared to F1 series, below the

main features:

●

GPIO mapped on AHB bus for better performance

●

I/O pin multiplexer and mapping: pins are connected to on-chip peripherals/modules

through a multiplexer that allows only one peripheral alternate function (AF) connected

to an I/O pin at a time. In this way, there can be no conflict between peripherals sharing

the same I/O pin.

●

More possibilities and features for I/O configuration

The L1 GPIO peripheral is a new design and thus the architecture, features and registers

are different from the GPIO peripheral in the F1 series, so any code written for the F1 series

using the GPIO needs to be rewritten to run on L1 series.

For more information about STM32L1’s GPIO programming and usage, please refer to the

"I/O pin multiplexer and mapping" section in the GPIO chapter of the STM32L1xx Reference

Manual (RM0038).

The table below presents the differences between GPIOs in the STM32F1 series and

STM32L1 series.

Table 11.

GPIO differences between STM32F1 series and STM32L1 series

GPIO

STM32F1 series

STM32L1 series

Input mode

Floating

General purpose

output

PP + PU

PP + PD

OD + PU

OD + PD

Alternate Function

output

PP + PU

PP + PD

OD + PU

OD + PD

Input / Output

Analog

Output speed

2 MHz

10 MHz

50 MHz

400KHz

2 MHz

10 MHz

40 MHz

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