readme.txt

这是我用stm32做的一个CAN测试程序。有兴趣的朋友可以看看。文件里并包含CAN协议

/******************** (C) COPYRIGHT 2007 STMicroelectronics ********************
* File Name          : readme.txt
* Author             : MCD Application Team
* Date First Issued  : 05/21/2007
* Description        : Description of the CAN Example.
********************************************************************************
* History:
* 05/21/2007: V0.3
********************************************************************************
* THE PRESENT SOFTWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
* WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME.
* AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT,
* INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE
* CONTENT OF SUCH SOFTWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING
* INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
*******************************************************************************/

Example description
===================
This example provides a description of how to set a communication with the bxCAN
in loopback mode:
- transmit and receive a standard data frame by polling at 100Kbit/S
- transmit and receive an extended data frame with interrupt at 500Kbit/S
- lit some LEDs depending of the program succeed or not

外部8M的时钟

RCC_PCLK1Config(RCC_HCLK_Div2);

APB1的时钟为4M 

CAN_InitStructure.CAN_Prescaler=5;

CAN 时钟 = 4M / 5 = 800 K 

CAN_InitStructure.CAN_BS1=CAN_BS1_8tq;
CAN_InitStructure.CAN_BS2=CAN_BS2_7tq;

1 + 8 + 7 = 16 Tq 

CAN 速度 = 800K / 16 = 50K
CAN的数据帧大体分为两种格式：标准格式和扩展格式。

| SOF(帧起始) | 仲裁域 | 控制域 | 数据域 | CRC域 | 应答域 | 帧结尾 |

- SOF(帧起始)：1位；标准格式和扩展格式一样。
- 仲裁域：
    标准格式为12位 = 11位标识符 + RTR位
    扩展格式为32位 = 11位标识符 + SRR位 + IDE位 + 18位标识符 + RTR位
  RTR = Remote Transmission Request Bit (远程发送请求位)
  SRR = Substitute Remote Request Bit (替代远程请求位)
  IDE = Identifier Extension Bit (标识符扩展位)
- 控制域：6位，= IDE/r1 + r0 + 数据长度代码，标准格式和扩展格式一样。
    数据长度代码 = (DLC3 + DLC2 + DLC1 + DLC0)
    r1、r0 为保留位
- 数据域：0~8个字节，先发送MSB。
- CRC域：共16位 = 15位CRC序列 + 1位CRC界定符；标准格式和扩展格式一样。
- 应答域：2位；标准格式和扩展格式一样。
- 帧结尾：7位；标准格式和扩展格式一样。

标准格式时共44~108位的长度；扩展格式时共64~128位的长度。


Directory contents
==================
stm32f10x_conf.h  Library Configuration file
stm32f10x_it.c    Interrupt handlers
stm32f10x_it.h    Interrupt handlers header file
main.c            Main program

Hardware environment
====================
 - This examples runs on STM32F10x-EVAL board

How to use it
=============
In order to make the program work, you must do the following :
- Create a project and setup all your toolchain's start-up files
- Compile the directory content files and required Library files :
  + stm32f10x_lib.c
  + stm32f10x_can.c
  + stm32f10x_rcc.c
  + stm32f10x_gpio.c
  + stm32f10x_nvic.c
  + stm32f10x_flash.c
    
- Link all compiled files and load your image into either RAM or FLASH
- Run the example

******************* (C) COPYRIGHT 2007 STMicroelectronics *****END OF FILE******