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ST STM32F31xx User Manual

ST STM32F31xx
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Page #314 background image
Reset and clock control (RCC)
UM1581
314/584
DocID023800 Rev 1
ï‚· RCC_PLLConfig()
ï‚· RCC_PLLCmd()
ï‚· RCC_PREDIV1Config()
ï‚· RCC_ClockSecuritySystemCmd()
ï‚· RCC_MCOConfig()
18.2.3 System, AHB, APB1 and APB2 busses clocks configuration functions
This section provide functions allowing to configure the System, AHB, APB1 and APB2
busses clocks.
1. Several clock sources can be used to drive the System clock (SYSCLK): HSI, HSE
and PLL. The AHB clock (HCLK) is derived from System clock through configurable
prescaler and used to clock the CPU, memory and peripherals mapped on AHB bus
(DMA and GPIO). APB1 (PCLK1) and APB2 (PCLK2) clocks are derived from AHB
clock through configurable prescalers and used to clock the peripherals mapped on
these busses. You can use "RCC_GetClocksFreq()" function to retrieve the
frequencies of these clocks.
2. The maximum frequency of the SYSCLK, HCLK, PCLK1 and PCLK2 is 72 MHz.
Depending on the maximum frequency, the FLASH wait states (WS) should be
adapted accordingly:
Wait states
HCLK clock frequency (MHz)
0WS(1CPU cycle)
0 < HCLK <= 24
1WS(2CPU cycles)
24 < HCLK <= 48
2WS(3CPU cycles)
48 < HCLK <= 72
3. After reset, the System clock source is the HSI (8 MHz) with 0 WS and prefetch is
disabled.
All the peripheral clocks are derived from the System clock (SYSCLK) except:
ï‚· The FLASH program/erase clock which is always HSI 8MHz clock.
ï‚· The USB 48 MHz clock which is derived from the PLL VCO clock.
ï‚· The USART clock which can be derived as well from HSI 8MHz, LSI or LSE.
ï‚· The I2C clock which can be derived as well from HSI 8MHz clock.
ï‚· The ADC clock which is derived from PLL output.
ï‚· The RTC clock which is derived from the LSE, LSI or 1 MHz HSE_RTC (HSE
divided by a programmable prescaler). The System clock (SYSCLK)
frequency must be higher or equal to the RTC clock frequency.
ï‚· IWDG clock which is always the LSI clock.
It is recommended to use the following software sequences to tune the number of wait
states needed to access the Flash memory with the CPU frequency (HCLK).
ï‚· Increasing the CPU frequency
 Program the Flash Prefetch buffer, using "FLASH_PrefetchBufferCmd(ENABLE)"
function
 Check that Flash Prefetch buffer activation is taken into account by reading
FLASH_ACR using the FLASH_GetPrefetchBufferStatus() function
 Program Flash WS to 1 or 2, using "FLASH_SetLatency()" function

Table of Contents

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ST STM32F31xx Specifications

General IconGeneral
BrandST
ModelSTM32F31xx
CategoryMicrocontrollers
LanguageEnglish

Summary

How to Use and Customize the Library

Library Configuration Parameters

Details configuration parameters that customize the library for specific applications via define statements.

Peripheral Initialization and Configuration

Step-by-step guide on how to initialize and configure a peripheral, including clock enabling.

Running Your First Example

Guides on loading and executing template examples, covering prerequisites and tool-specific steps.

Developing Your First Application

Outlines the typical starting point and steps for developing an application from scratch.

Analog-to-digital converter (ADC) Firmware Driver

ADC Firmware Driver API Description

Lists and describes the various functions available in the ADC library for peripheral control.

Controller Area Network (bxCAN) Firmware Driver

CAN Firmware Driver API Description

Lists and describes the various functions available in the CAN library for peripheral control.

Comparators (COMP) Firmware Driver

COMP Firmware Driver API Description

Lists and describes the various functions available in the COMP library for peripheral control.

CRC Calculation Unit (CRC) Firmware Driver

CRC Firmware Driver API Description

Lists and describes the various functions for CRC configuration and computation.

Digital-to-Analog Converter (DAC) Firmware Driver

DAC Firmware Driver API Description

Lists and describes the various functions for DAC peripheral control and data transfer.

DMA Controller (DMA) Firmware Driver

DMA Firmware Driver API Description

Lists and describes functions for DMA initialization, configuration, and data transfers.

External Interrupt/Event Controller (EXTI) Firmware Driver

EXTI Firmware Driver API Description

Lists and describes functions for EXTI features, usage, initialization, and interrupt management.

FLASH Memory (FLASH) Firmware Driver

FLASH Firmware Driver API Description

Lists and describes functions for FLASH interface configuration and memory programming.

General-purpose I/Os (GPIO) Firmware Driver

GPIO Firmware Driver API Description

Lists and describes functions for GPIO usage, initialization, read/write, and alternate functions.

Inter-integrated Circuit Interface (I2C) Firmware Driver

I2C Firmware Driver API Description

Lists and describes functions for I2C usage, initialization, communication, SMBUS, and registers management.

Independent Watchdog (IWDG) Firmware Driver

IWDG Firmware Driver API Description

Lists and describes functions for IWDG features, usage, prescaler, activation, and flag management.

Operational Amplifier (OPAMP) Firmware Driver

OPAMP Firmware Driver API Description

Lists and describes functions for OPAMP peripheral features, usage, and initialization.

Power Control (PWR) Firmware Driver

PWR Firmware Driver API Description

Lists and describes functions for backup domain access, PVD configuration, and low power modes.

Reset and Clock Control (RCC) Firmware Driver

RCC Firmware Driver API Description

Lists and describes functions for RCC features, clock configuration, and peripheral clocks.

Real-time Clock (RTC) Firmware Driver

RTC Firmware Driver API Description

Lists and describes functions for RTC operating conditions, domain access, and time/date configuration.

Serial Peripheral Interface (SPI) Firmware Driver

SPI Firmware Driver API Description

Lists and describes functions for SPI usage, initialization, data transfers, CRC calculation, and DMA.

System Configuration Controller (SYSCFG) Firmware Driver

SYSCFG Firmware Driver API Description

Lists and describes functions for SYSCFG usage, initialization, and configuration.

General-Purpose Timers (TIM) Firmware Driver

TIM Firmware Driver API Description

Lists and describes functions for TIM output compare, input capture, advanced control, and synchronization management.

Universal Synchronous Asynchronous Receiver Transmitter (USART) Firmware Driver

USART Firmware Driver API Description

Lists and describes functions for USART usage, initialization, RS485, DMA, interrupts, STOP mode, and AutoBaudRate.

Window Watchdog (WWDG) Firmware Driver

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