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AN4296: 产品描述The purpose of this application note is to give a presentation; 文件大小1MB，共25页; 制造商ST(意法半导体); 官网地址http://www.st.com/

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AN4296概述

The purpose of this application note is to give a presentation

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AN4296

Application note

Overview and tips for using STM32F303/328/334/358xx CCM RAM

with IAR EWARM, Keil MDK-ARM and GNU-based toolchains

Introduction

The purpose of this application note is to give a presentation of the core coupled memory

(CCM) RAM available on STM32F303xB/xC and STM32F358xC microcontrollers and

describe what is required to execute part of the application code from this memory region

using different toolchains.

This application note is divided into four sections: the first section gives an overview of the

STM32F3 CCM RAM, while the next sections describe the steps required to execute part of

the application code from CCM RAM using the following toolchains:

•

IAR EWARM

KEIL MDK-ARM

™

RIDE and Atollic GNU based toolchain

The procedures described throughout the document are applicable to other RAM regions

such as the CCM data RAM of some F4 devices, or external SRAM.

Refer to

Table 1

for the list microcontrollers embedding CCM RAM.

Table 1. Applicable products

Product family

Microcontrollers

Part numbers or product categories

STM32F303xB, STM32F303xC, STM32F358xC

STM32F303x6/x8, STM32F328x8, STM32F334x4/x6/x8

September 2014

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www.st.com

Contents

AN4296

Contents

Overview of STM32F303xB/C and STM32F358xC CCM RAM . . . . . . . . 5

1.1

1.2

Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

STM32F303xB/C and STM32F358xC CCM RAM features . . . . . . . . . . . . 6

1.2.1

1.2.2

1.2.3

1.2.4

CCM RAM mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

CCM RAM remapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

CCM RAM write protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

CCM RAM parity check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Execute application code from CCM RAM

using the IAR EWARM toolchain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.1

Executing a simple code from CCM RAM (except for interrupt handler) . . 8

2.1.1

2.1.2

Executing a source file from CCM RAM . . . . . . . . . . . . . . . . . . . . . . . . . 9

Executing one or more functions from CCM RAM . . . . . . . . . . . . . . . . . 10

Updating the linker file (.icf) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Updating the startup file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Place the interrupt handler in CCM RAM . . . . . . . . . . . . . . . . . . . . . . . . 13

Remap the vector table to CCM RAM . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.2

Executing an interrupt handler from CCM RAM . . . . . . . . . . . . . . . . . . . . .11

2.2.1

2.2.2

2.2.3

2.2.4

2.3

Executing a library (.a) from CCM RAM . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Execute application code from CCM RAM

using the KEIL MDK-ARM toolchain . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.1

3.2

3.3

Executing a function or an interrupt handler from CCM RAM . . . . . . . . . 16

Executing a source file from CCM RAM . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Executing a library or a library module from CCM RAM . . . . . . . . . . . . . . 18

Execute application code from CCM RAM

using a GNU-based toolchain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.1

4.2

4.3

Executing a function or an interrupt handler from CCM RAM . . . . . . . . . 19

Executing a file from CCM RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Executing a library from CCM RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

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List of figures

AN4296

List of figures

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

Figure 11.

Figure 12.

Figure 13.

Figure 14.

Figure 15.

Figure 16.

Figure 17.

Figure 18.

Figure 19.

Figure 20.

Figure 21.

STM32F303xB/xC and STM32F358xC system architecture . . . . . . . . . . . . . . . . . . . . . . . . 6

EWARM linker update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

EWARM file placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

EWARM function placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

EWARM linker update for interrupt handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

EWARM startup file update for interrupt handler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

CCM RAM area definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

EWARM section initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

EWARM library placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

EWARM library module placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

MDK-ARM scatter file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

MDK-ARM Options menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

MDK-ARM function placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

MDK-ARM target memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

MDK-ARM file placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

MDK-ARM library placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

GNU linker update . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

GNU linker section definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

GNU function placement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

GNU file placement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

GNU library placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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AN4296

Overview of STM32F303xB/C and STM32F358xC CCM RAM

1.1

Overview of STM32F303xB/C and STM32F358xC CCM

RAM

Purpose

The STM32F303xB/C and STM32F358xC CCM RAM is tightly coupled with the Cortex™

core. it is primarily intended to execute code at maximum system clock frequency (72 MHz)

without any wait state penalty. It thus allows to significantly decrease critical task execution

time, compared to code execution from Flash memory.

CCM RAM is typically used for real-time and computation intensive routines, such as:

•

Digital power conversion control loops (switch mode power supplies, lighting)

Field-oriented 3-phase motor control

Real-time DSP tasks

When code is located in CCM RAM and data stored in the regular SRAM, the Cortex-M4

core is in the optimum Harvard configuration. A dedicated zero-wait state memory is

connected to each of its I- and D-bus (refer to

Figure 1: STM32F303xB/xC and

STM32F358xC system architecture)

and can thus perform at 1.25DMIPS/MHz up to

72 MHz, with a deterministic performance of 90 DMIPS. This also guarantees a minimal

latency if interrupt service routines are placed in the CCM RAM.

Example

A benchmark between the STM32F103xx and STM32F303xx microcontrollers using

STMicroelectronics MC library V3.4 shows that in case of single motor control using 3 shunt

algorithm, the FOC total execution time for STM32F303xx is 16.97 µs compared to 21.3 µs

in STMF103xx (see note below); with FOC core and sensorless core loops running from

CCM RAM for STM32F303xx. This means that the STM32F303xx is 20.33 % faster than the

STM32F103xx thanks to the CCM RAM.

Note:

FOC routines are programmed in structured C, so the values provided above do not

represent the fastest possible execution both for STM32F103xx and STM32F303xx. In

addition, the execution time is also function of the compiler used and of its version.

When the CCM RAM is not used for code, it can hold data like an extra SRAM memory.

However it cannot be accessed through DMA. It is not recommended to place both code

and data together in the CCM, since the Cortex core will have to fetch code and data from

the same memory with the risk of collisions. The core would then be in the Von Neuman

configuration, and its performance would drop from 1.25DMIPS/MHz to below

1DMIPS/MHz.

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AN4296

AN4296概述

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