Analog Configuration; Using The Osc32_In/Osc32_Out Pins As Gpio Pc14/Pc15; Port Pins; Using The Osc_In/Osc_Out Pins As Gpio Ph0/Ph1 Port Pins - ST STM32F412 Reference Manual

Advanced arm-based 32-bit mcus

Table of Contents

Analog configuration

When the I/O port is programmed as analog configuration:

The output buffer is disabled

The Schmitt trigger input is deactivated, providing zero consumption for every analog

value of the I/O pin. The output of the Schmitt trigger is forced to a constant value (0).

The weak pull-up and pull-down resistors are disabled

Read access to the input data register gets the value "0"

In the analog configuration, the I/O pins cannot be 5 Volt tolerant.

From on-chip

The LSE oscillator pins OSC32_IN and OSC32_OUT can be used as general-purpose

PC14 and PC15 I/Os, respectively, when the LSE oscillator is off. The PC14 and PC15 I/Os

are only configured as LSE oscillator pins OSC32_IN and OSC32_OUT when the LSE

oscillator is ON. This is done by setting the LSEON bit in the RCC_BDCR register. The LSE

has priority over the GPIO function.

The PC14/PC15 GPIO functionality is lost when the 1.2 V domain is powered off (by the

device entering the standby mode) or when the backup domain is supplied by V

more supplied). In this case the I/Os are set in analog input mode.

The HSE oscillator pins OSC_IN/OSC_OUT can be used as general-purpose PH0/PH1

I/Os, respectively, when the HSE oscillator is OFF. (after reset, the HSE oscillator is off). The

PH0/PH1 I/Os are only configured as OSC_IN/OSC_OUT HSE oscillator pins when the

HSE oscillator is ON. This is done by setting the HSEON bit in the RCC_CR register. The

HSE has priority over the GPIO function.

shows the high-impedance, analog-input configuration of the I/O port bit.

Input driver

RM0402 Rev 6

General-purpose I/Os (GPIO)

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