我正在尝试按照以下步骤在我的ARM9（SAM9X25）上读取和写入寄存器：http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka3750.html我以下面的代码结束：
try{
System.Reflection.Assembly sampleAssembly = System.Reflection.Assembly.LoadFrom(dll);
List<Type> list= sampleAssembly.GetTypes().Where(p =>
p.Namespace == dll &&
p.Name.Contains("Plugin")
).ToList();
Type myType=list.FirstOrDefault();
//Type myType = sampleAssembly.GetType("Plugin");
System.Reflection.MethodInfo method = myType.GetMethod("activate");
object myInstance = Activator.CreateInstance(myType);
method.Invoke(myInstance, new object[]{this});
}
我在Ubuntu 16.04中交叉编译了我的代码#include "stdio.h"
#define PIO_WPMR_BANK_D 0xFFFFFAE4 // PIO Write Protection Mode Register Bank D
#define PIO_PUER_BANK_D 0xFFFFFA64 // PIO Pull-Up Enable Register Bank D
#define PIO_PUSR_BANK_D 0xFFFFFA68 // PIO Pull-Up Status Register Bank D
#define MASK_LED7 0xFFDFFFFF // LED7 Mask
#define DESABLE_WRITE_PROTECTION_BANK_D 0x50494F00 // Desable write protection Bank D
int main(void) {
printf("test");
unsigned int volatile * const register_PIO_WPMR_BANK_D = (unsigned int *) PIO_WPMR_BANK_D;
unsigned int volatile * const register_PIO_PUSR_BANK_D = (unsigned int *) PIO_PUSR_BANK_D;
unsigned int volatile * const port_D = (unsigned int *) PIO_PUER_BANK_D;
*register_PIO_WPMR_BANK_D = DESABLE_WRITE_PROTECTION_BANK_D;
*port_D = *register_PIO_PUSR_BANK_D & MASK_LED7;
return 0; }
，但我在程序执行期间arm-linux-gnueabi-gcc gpio.c -o gpio之后有一个Segmentation Fault我的董事会。
我知道地址是对的...那么为什么我会有这个错误呢？这是好方法吗？
谢谢你的帮助！
解决方案：
谢谢@vlk我可以让它工作！这是切换LED的一个小例子：
printf 编辑：
在评论中回答 3）。如果你想让它适用于所有的偏移量（即：mmap example），你必须改变mmap和如此的分配：
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <fcntl.h>
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
#define _PIOD_BANK_D 0xA00
#define _PIO_OFFSET 0xFFFFF000
/* When executing this on the board :
long sz = sysconf(_SC_PAGESIZE);
printf("%ld\n\r",sz);
We have 4096.
*/
#define _MAP_SIZE 0x1000 // 4096
#define _WPMR_OFFSET 0x0E4 // PIO Write Protection Mode Register Bank D
#define _PIO_ENABLE 0x000
#define _PIO_DISABLE 0x004
#define _PIO_STATUS 0x008
#define _OUTPUT_ENABLE 0x010
#define _OUTPUT_DISABLE 0x014
#define _OUTPUT_STATUS 0x018
#define _FILTER_ENABLE 0x020
#define _FILTER_DISABLE 0x024
#define _FILTER_STATUS 0x028
#define _OUTPUT_DATA_SET 0x030
#define _OUTPUT_DATA_CLEAR 0x034
#define _OUTPUT_DATA_STATUS 0x038
#define _PIN_DATA_STATUS 0x03c
#define _MULTI_DRIVER_ENABLE 0x050
#define _MULTI_DRIVER_DISABLE 0x054
#define _MULTI_DRIVER_STATUS 0x058
#define _PULL_UP_DISABLE 0x060
#define _PULL_UP_ENABLE 0x064
#define _PULL_UP_STATUS 0x068
#define _PULL_DOWN_DISABLE 0x090
#define _PULL_DOWN_ENABLE 0x094
#define _PULL_DOWN_STATUS 0x098
#define _DISABLE_WRITE_PROTECTION 0x50494F00 // Desable write protection
#define LED_PIN 21
int main(void) {
volatile void *gpio_addr;
volatile unsigned int *gpio_enable_addr;
volatile unsigned int *gpio_output_mode_addr;
volatile unsigned int *gpio_output_set_addr;
volatile unsigned int *gpio_output_clear_addr;
volatile unsigned int *gpio_data_status_addr;
volatile unsigned int *gpio_write_protection_addr;
int fd = open("/dev/mem", O_RDWR|O_SYNC);
if (fd < 0){
fprintf(stderr, "Unable to open port\n\r");
exit(fd);
}
gpio_addr = mmap(NULL, _MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, _PIO_OFFSET);
if(gpio_addr == MAP_FAILED){
handle_error("mmap");
}
gpio_write_protection_addr = gpio_addr + _PIOD_BANK_D + _WPMR_OFFSET;
gpio_enable_addr = gpio_addr + _PIOD_BANK_D + _PIO_ENABLE;
gpio_output_mode_addr = gpio_addr + _PIOD_BANK_D + _OUTPUT_ENABLE;
gpio_output_set_addr = gpio_addr + _PIOD_BANK_D + _OUTPUT_DATA_SET;
gpio_output_clear_addr = gpio_addr + _PIOD_BANK_D + _OUTPUT_DATA_CLEAR;
gpio_data_status_addr = gpio_addr + _PIOD_BANK_D + _OUTPUT_DATA_STATUS;
*gpio_write_protection_addr = _DISABLE_WRITE_PROTECTION;
*gpio_enable_addr = 1 << LED_PIN;
*gpio_output_mode_addr = 1 << LED_PIN; // Output
// If LED
if((*gpio_data_status_addr & (1<<LED_PIN)) > 0){
*gpio_output_clear_addr = 1 << LED_PIN;
}else{
*gpio_output_set_addr = 1 << LED_PIN;
}
return 0;
}
和mmap：
#define _PIO_OFFSET 0xFFFFFA00 // Instead of 0xFFFFF000
#define _MAP_SIZE 0x1000 // 4096
#define _MAP_MASK (_MAP_SIZE - 1)
#define _PA_OFFSET _PIO_OFFSET & ~_MAP_MASK
对于作业：
gpio_addr = mmap(NULL, _MAP_SIZE + _PIO_OFFSET - _PA_OFFSET, PROT_READ | PROT_WRITE, MAP_SHARED, fd, _PA_OFFSET);
答案 0 :(得分：3)
您无法直接访问寄存器，因为Linux使用MMU，这会为您的应用创建与物理MCU地址空间不同的虚拟地址空间，并且在此虚拟地址空间之外的访问会导致分段错误。
只有在Linux中访问这些寄存器的方法（如果你不想编写内核驱动程序）是打开文件/ dev / mem作为文件并用mmap
映射它例如，我有一个小型python库，用于访问Atmel SAM MCU gpiosam上的GPIO寄存器。你可以启发并将它移植到C。
答案 1 :(得分：1)
<强> import java.awt.*;
import javax.swing.*;
//https://stackoverflow.com/questions/35287367/changing-desktopicon-width-on-nimbus
public class DesktopIconWidthTest2 {
public JComponent makeUI() {
JDesktopPane desktop = new JDesktopPane();
desktop.setDesktopManager(new DefaultDesktopManager() {
@Override public void iconifyFrame(JInternalFrame f) {
Rectangle r = this.getBoundsForIconOf(f);
r.width = f.getDesktopIcon().getPreferredSize().width;
f.getDesktopIcon().setBounds(r);
super.iconifyFrame(f);
}
});
desktop.add(createFrame("looooooooooooong title #", 1));
desktop.add(createFrame("#", 0));
return desktop;
}
private JInternalFrame createFrame(String t, int i) {
JInternalFrame f = new JInternalFrame(t + i, true, true, true, true);
f.setDesktopIcon(new JInternalFrame.JDesktopIcon(f) {
@Override public Dimension getPreferredSize() {
Dimension d = f.getMinimumSize();
String title = f.getTitle();
FontMetrics fm = getFontMetrics(getFont());
//Magic Number 16: margin?
d.width += SwingUtilities.computeStringWidth(fm, title) - 16;
return d;
}
});
f.setSize(200, 100);
f.setVisible(true);
f.setLocation(5 + 40 * i, 5 + 50 * i);
return f;
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> {
try {
UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel");
// MetalLookAndFeel: UIManager.put("DesktopIcon.width", 500);
} catch (Exception e) {
e.printStackTrace();
}
JFrame f = new JFrame();
f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
f.getContentPane().add(new DesktopIconWidthTest2().makeUI());
f.setSize(320, 240);
f.setLocationRelativeTo(null);
f.setVisible(true);
});
}
}
busybox devmem是一个很小的CLI实用程序，可以映射busybox devmem。
你可以在Ubuntu中使用：sudo apt-get install busybox
用法：从物理地址/dev/mem读取4个字节：
0x12345678将sudo busybox devmem 0x12345678
写入该地址：
0x9abcdef0有关如何测试的一些提示，请参阅此处：Accessing physical address from user space
还提到了：https://unix.stackexchange.com/questions/4948/shell-command-to-read-device-registers