访问内存映射I / O [英] Access Memory Mapped I/O

问题描述

我非常新的嵌入式系统编程，我只需要学习如何通过c ++代码操作给定的。

给定：

电机1映射到0x60000000

电机2映射到0x50000000

以下是当前32位寄存器的定义

  REGISTER NAME | BYTE OFFSET |注意
 --------------------------------------------- ------------------------- 
 motor_interrupt 0x00服务中断
 
 motor_status 0x01启用按需访问状态元素
 motor_command 0x02启用电机命令
 
 
 
注册名称| NAME | BITS |访问类型| DESC 
 --------------------------------------------- ------------------------------------- 
 
 motor_interrupt_register 
关闭0当电机转换到关闭位置时，R / W为高电平
 OPEN 1当电机转换到OPEN位置时，R / W为高电平
 RESERVED 2.31 N / A保留以备将来使用
 
 motor_status 
 
速度0.2 R速度计数/秒
状态3 R电机的当前状态
 POSITION 4.13 R电机的当前位置
 RESERVED 14.31 n / a保留为未来使用
  

我发现使用给定的C ++代码很难看到，在这一点上我是知道我需要访问regi ster_name并将其位设置为执行特定任务或读取注册名称以获取状态。

如果在c ++代码中使用它，我想我可以理解它。给定的是一个自动门系统（我没有写出按钮的细节）。我需要访问register_name或c ++中的byte_offset吗？

您的帮助将非常欣赏

解决方案

C / C ++例如读取中断/状态寄存器：

  volatile uint32_t * const motor1 =（uint32_t *）0x60000000; //电机1和2的基址
 volatile uint32_t * const motor2 =（uint32_t *）0x50000000; 
 
枚举//从基址寄存器偏移
 {
 motor_interrupt，// 0x00  - 服务中断
 motor_status，// 0x01  - 启用按需访问状态元素
 motor_command // 0x02  - 启用电机命令
} 
 
 //读状态/中断寄存器
 
 uint32_t current_int_1 = motor1 [motor_interrupt]; 
 uint32_t current_int_2 = motor2 [motor_interrupt]; 
 
 uint32_t current_status_1 = motor1 [motor_status]; 
 uint32_t current_status_2 = motor2 [motor_status]; 
  

类似于将32位值写入命令寄存器：

  motor1 [motor_command] = 0x8000 | （0x12 <6）| 0×01; 
 motor2 [motor_command] = 0x0; 
  

I am very new to embedded system programming, I just need to learn how to manipulate the given via c++ code.

Given:

Motor 1 is mapped to 0x60000000

Motor 2 is mapped to 0x50000000

the following are the definitions of current 32-bit registers

REGISTER NAME            |     BYTE OFFSET        |     NOTES
----------------------------------------------------------------------
motor_interrupt               0x00                 service interrupts

motor_status                  0x01                 enable on demand access to status elements
motor_command                 0x02                 enable command of the motor



REGISTER NAME           |   NAME   |  BITS   | ACCESS TYPE   | DESC 
----------------------------------------------------------------------------------

motor_interrupt_register
                           CLOSED      0          R/W         high when motor transitions to CLOSED position
                           OPEN        1          R/W         high when motor transitions to OPEN position
                           RESERVED    2.31       N/A         reserved for future use

motor_status        

                           SPEED       0.2         R          speed in counts/seconds
                           STATE        3          R          current state of motor
                           POSITION    4.13        R          current position of the motor
                           RESERVED    14.31       n/a         reserved for future use

I find it hard to see a sample c++ code using the given, At this point what i know is I need to access the register_name and set their bits to perform specific task or read the register name to get the status for example.

I think I can understand it more if it is used in a c++ code. The given is a automatic door system ( i didnt write the button details). Will I need to access the register_name or the byte_offset in c++?

Your help would be very much appreciated

解决方案

C/C++ example to read interrupt/status registers:

volatile uint32_t * const motor1 = (uint32_t *)0x60000000; // base addresses for motors 1 and 2
volatile uint32_t * const motor2 = (uint32_t *)0x50000000;

enum  // register offsets from base address
{
    motor_interrupt, // 0x00 - service interrupts
    motor_status,    // 0x01 - enable on demand access to status elements
    motor_command    // 0x02 - enable command of the motor
}

// read status/interrupt registers

uint32_t current_int_1 = motor1[motor_interrupt];
uint32_t current_int_2 = motor2[motor_interrupt];

uint32_t current_status_1 = motor1[motor_status];
uint32_t current_status_2 = motor2[motor_status];

Similarly to write 32 bit values to to the command registers:

motor1[motor_command] = 0x8000 | (0x12 << 6) | 0x01;
motor2[motor_command] = 0x0;

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