<!--
* @Author: rx-ted
* @Date: 2023-07-18 17:45:19
* @LastEditors: rx-ted
* @LastEditTime: 2023-07-18 18:19:47
-->
# Linux下i2c驱动OLED ssd1306
## 参数
- ssd1306
- 128*32
- 0x3c
- i2c0
## dts修改
```c
// build/boards/cv180x/cv1800b_milkv_duo_sd/dts_riscv/cv1800b_milkv_duo_sd.dts
// 速率 名称 地址，随便修改，一旦有新的设备地址，可以在i2c0下追加新设备
&i2c0 {
status = "okay";
ssd1306:ssd1306@3c {
compatible = "oled12832,ssd1306";
reg = <0x3c>;
};
};
编译
修改好了dts设备树，需要重新编译，见教程：传送
最后得到image镜像，在milkv-duo上烧录即可。
i2cdetect -yr 0
# 可以看到0x3c位置
# 等到导入KO文件，就变成UU，表示成功
源代码获取KO文件
在sdk下新建driver，然后再新建ssd1306文件夹，接着新文件命名为ssd1306.c，不想分头文件
借鉴某位大佬源代码，稍微修改
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kdev_t.h>
#include <linux/module.h>
#include <linux/stat.h>
#include <linux/uaccess.h>
/*
全局静态变量：希望全局变量仅限于在本源文件中使用，在其他源文件中不能引用，也就是说限制其作用域只在
定义该变量的源文件内有效，而在同一源程序的其他源文件中不能使用
*/
#define OK (0)
#define ERROR (-1)
/* I2C设备驱动 */
static struct i2c_driver oled_driver;
/* I2C从设备 */
static struct i2c_client *oled_client;
/* i2c设备地址 */
static unsigned short addr = 0x3C;
/* i2c驱动需要探测的从设备地址 */
static unsigned short address_list[] = {0x3c, 0xfffeU}; // 0xfffeU 结束标志
/* 设备编号 */
static dev_t devid;
/* 设备class */
static struct class *oled_class;
/* oled字符设备哦 */
static struct cdev i2c_cdev;
/*****************************************************************************************************
*
* 从ASCII0x20开始 取模方向：逐列式 每列1个字节，共6列 即一个字节占8行6列
* 取模走向：低位在前
*
*****************************************************************************************************/
static const u8 ASCII6x8[][6] =
{
{0x00, 0x00, 0x00, 0x00, 0x00, 0x00}, // sp ASCII 0x20
{0x00, 0x00, 0x00, 0x2f, 0x00, 0x00}, // !
{0x00, 0x00, 0x07, 0x00, 0x07, 0x00}, // "
{0x00, 0x14, 0x7f, 0x14, 0x7f, 0x14}, // #
{0x00, 0x24, 0x2a, 0x7f, 0x2a, 0x12}, // $
{0x00, 0x62, 0x64, 0x08, 0x13, 0x23}, // %
{0x00, 0x36, 0x49, 0x55, 0x22, 0x50}, // &
{0x00, 0x00, 0x05, 0x03, 0x00, 0x00}, // '
{0x00, 0x00, 0x1c, 0x22, 0x41, 0x00}, // (
{0x00, 0x00, 0x41, 0x22, 0x1c, 0x00}, // )
{0x00, 0x14, 0x08, 0x3E, 0x08, 0x14}, // *
{0x00, 0x08, 0x08, 0x3E, 0x08, 0x08}, // +
{0x00, 0x00, 0x00, 0xA0, 0x60, 0x00}, // ,
{0x00, 0x08, 0x08, 0x08, 0x08, 0x08}, // -
{0x00, 0x00, 0x60, 0x60, 0x00, 0x00}, // .
{0x00, 0x20, 0x10, 0x08, 0x04, 0x02}, // /
{0x00, 0x3E, 0x51, 0x49, 0x45, 0x3E}, // 0
{0x00, 0x00, 0x42, 0x7F, 0x40, 0x00}, // 1
{0x00, 0x42, 0x61, 0x51, 0x49, 0x46}, // 2
{0x00, 0x21, 0x41, 0x45, 0x4B, 0x31}, // 3
{0x00, 0x18, 0x14, 0x12, 0x7F, 0x10}, // 4
{0x00, 0x27, 0x45, 0x45, 0x45, 0x39}, // 5
{0x00, 0x3C, 0x4A, 0x49, 0x49, 0x30}, // 6
{0x00, 0x01, 0x71, 0x09, 0x05, 0x03}, // 7
{0x00, 0x36, 0x49, 0x49, 0x49, 0x36}, // 8
{0x00, 0x06, 0x49, 0x49, 0x29, 0x1E}, // 9
{0x00, 0x00, 0x36, 0x36, 0x00, 0x00}, // :
{0x00, 0x00, 0x56, 0x36, 0x00, 0x00}, // ;
{0x00, 0x08, 0x14, 0x22, 0x41, 0x00}, // <
{0x00, 0x14, 0x14, 0x14, 0x14, 0x14}, // =
{0x00, 0x00, 0x41, 0x22, 0x14, 0x08}, // >
{0x00, 0x02, 0x01, 0x51, 0x09, 0x06}, // ?
{0x00, 0x32, 0x49, 0x59, 0x51, 0x3E}, // @
{0x00, 0x7C, 0x12, 0x11, 0x12, 0x7C}, // A
{0x00, 0x7F, 0x49, 0x49, 0x49, 0x36}, // B
{0x00, 0x3E, 0x41, 0x41, 0x41, 0x22}, // C
{0x00, 0x7F, 0x41, 0x41, 0x22, 0x1C}, // D
{0x00, 0x7F, 0x49, 0x49, 0x49, 0x41}, // E
{0x00, 0x7F, 0x09, 0x09, 0x09, 0x01}, // F
{0x00, 0x3E, 0x41, 0x49, 0x49, 0x7A}, // G
{0x00, 0x7F, 0x08, 0x08, 0x08, 0x7F}, // H
{0x00, 0x00, 0x41, 0x7F, 0x41, 0x00}, // I
{0x00, 0x20, 0x40, 0x41, 0x3F, 0x01}, // J
{0x00, 0x7F, 0x08, 0x14, 0x22, 0x41}, // K
{0x00, 0x7F, 0x40, 0x40, 0x40, 0x40}, // L
{0x00, 0x7F, 0x02, 0x0C, 0x02, 0x7F}, // M
{0x00, 0x7F, 0x04, 0x08, 0x10, 0x7F}, // N
{0x00, 0x3E, 0x41, 0x41, 0x41, 0x3E}, // O
{0x00, 0x7F, 0x09, 0x09, 0x09, 0x06}, // P
{0x00, 0x3E, 0x41, 0x51, 0x21, 0x5E}, // Q
{0x00, 0x7F, 0x09, 0x19, 0x29, 0x46}, // R
{0x00, 0x46, 0x49, 0x49, 0x49, 0x31}, // S
{0x00, 0x01, 0x01, 0x7F, 0x01, 0x01}, // T
{0x00, 0x3F, 0x40, 0x40, 0x40, 0x3F}, // U
{0x00, 0x1F, 0x20, 0x40, 0x20, 0x1F}, // V
{0x00, 0x3F, 0x40, 0x38, 0x40, 0x3F}, // W
{0x00, 0x63, 0x14, 0x08, 0x14, 0x63}, // X
{0x00, 0x07, 0x08, 0x70, 0x08, 0x07}, // Y
{0x00, 0x61, 0x51, 0x49, 0x45, 0x43}, // Z
{0x00, 0x00, 0x7F, 0x41, 0x41, 0x00}, // [
{0x00, 0x55, 0x2A, 0x55, 0x2A, 0x55}, // 55
{0x00, 0x00, 0x41, 0x41, 0x7F, 0x00}, // ]
{0x00, 0x04, 0x02, 0x01, 0x02, 0x04}, // ^
{0x00, 0x40, 0x40, 0x40, 0x40, 0x40}, // _
{0x00, 0x00, 0x01, 0x02, 0x04, 0x00}, // '
{0x00, 0x20, 0x54, 0x54, 0x54, 0x78}, // a
{0x00, 0x7F, 0x48, 0x44, 0x44, 0x38}, // b
{0x00, 0x38, 0x44, 0x44, 0x44, 0x20}, // c
{0x00, 0x38, 0x44, 0x44, 0x48, 0x7F}, // d
{0x00, 0x38, 0x54, 0x54, 0x54, 0x18}, // e
{0x00, 0x08, 0x7E, 0x09, 0x01, 0x02}, // f
{0x00, 0x18, 0xA4, 0xA4, 0xA4, 0x7C}, // g
{0x00, 0x7F, 0x08, 0x04, 0x04, 0x78}, // h
{0x00, 0x00, 0x44, 0x7D, 0x40, 0x00}, // i
{0x00, 0x40, 0x80, 0x84, 0x7D, 0x00}, // j
{0x00, 0x7F, 0x10, 0x28, 0x44, 0x00}, // k
{0x00, 0x00, 0x41, 0x7F, 0x40, 0x00}, // l
{0x00, 0x7C, 0x04, 0x18, 0x04, 0x78}, // m
{0x00, 0x7C, 0x08, 0x04, 0x04, 0x78}, // n
{0x00, 0x38, 0x44, 0x44, 0x44, 0x38}, // o
{0x00, 0xFC, 0x24, 0x24, 0x24, 0x18}, // p
{0x00, 0x18, 0x24, 0x24, 0x18, 0xFC}, // q
{0x00, 0x7C, 0x08, 0x04, 0x04, 0x08}, // r
{0x00, 0x48, 0x54, 0x54, 0x54, 0x20}, // s
{0x00, 0x04, 0x3F, 0x44, 0x40, 0x20}, // t
{0x00, 0x3C, 0x40, 0x40, 0x20, 0x7C}, // u
{0x00, 0x1C, 0x20, 0x40, 0x20, 0x1C}, // v
{0x00, 0x3C, 0x40, 0x30, 0x40, 0x3C}, // w
{0x00, 0x44, 0x28, 0x10, 0x28, 0x44}, // x
{0x00, 0x1C, 0xA0, 0xA0, 0xA0, 0x7C}, // y
{0x00, 0x44, 0x64, 0x54, 0x4C, 0x44}, // z
{0x14, 0x14, 0x14, 0x14, 0x14, 0x14} // horiz lines
};
/*************************************************************
*
* Function : 通过SPI协议写命令
* Input : data 数据
* Return : 写入字节长度 负数写入失败
*
**************************************************************/
static int oled_write_cmd(unsigned char cmd)
{
struct i2c_msg msg[1];
unsigned char cmds[2];
cmds[0] = 0x00;
cmds[1] = cmd;
/* 数据传输三要素：源，目的，长度 */
msg[0].addr = oled_client->addr; /* 目的 */
msg[0].buf = cmds; /* 源 */
msg[0].len = 2; /* 长度为字节 = 数据 + 地址 */
msg[0].flags = 0; /* 0表示写 */
if (i2c_transfer(oled_client->adapter, msg, 1) == 1)
return 2;
else
return ERROR;
}
/*************************************************************
*
* Function : 通过SPI协议写数据
* Input : data 数据
* Return : 写入字节长度 负数写入失败
*
**************************************************************/
static int oled_write_data(unsigned char data)
{
struct i2c_msg msg[1];
unsigned char datas[2];
datas[0] = 0x40;
datas[1] = data;
/* 数据传输三要素：源，目的，长度 */
msg[0].addr = oled_client->addr; /* 目的 */
msg[0].buf = datas; /* 源 */
msg[0].len = 2; /* 长度为2字节 = 数据 + 地址 */
msg[0].flags = 0; /* 0表示写 */
if (i2c_transfer(oled_client->adapter, msg, 1) == 1)
return 2;
else
return ERROR;
}
/*************************************************************
*
* Function : 坐标设定
* Input : x x坐标 0x00~0x7F
* y y坐标 0~7
*
**************************************************************/
static void oled_pos(u8 x, u8 y)
{
oled_write_cmd(0xB0 + y);
oled_write_cmd(((x & 0xF0) >> 4) | 0x10); /* 设置列地址高四位 */
oled_write_cmd(x & 0x0F); /* 设置列地址低四位 */
}
/*************************************************************
*
* Function : 清屏
*
**************************************************************/
static void oled_clear(void)
{
u8 x;
u8 y;
for (y = 0; y < 8; y++)
{
oled_write_cmd(0xB0 + y); /* 选择页 */
oled_write_cmd(0x00); /* 设置列地址低四位 */
oled_write_cmd(0x10); /* 设置列地址高四位 */
for (x = 0; x < 0x80; x++)
oled_write_data(0x00); /* 每次清1列 */
}
}
/***************************************************************************************************
*
* Function : 写入一组标准ASCII字符串 一个字节占8行6列
* Input : x 设置列地址0~0X7F
* y 设置页地址0~7
* str 要显示的字符
*
**************************************************************************************************/
static void oled_p6x8str(u8 x, u8 y, u8 *str)
{
u8 i = 0;
u8 j = 0;
u8 k = 0;
while (str[j] != '\0')
{
while ((str[j] < 0x20) || (str[j] > 0x80)) /* 当写入的没有对应的点阵时 显示空格 */
str[j] = 32;
k = str[j] - 32;
if (x > 121)
{
x = 0;
y++;
}
oled_pos(x, y); /* 选中坐标 */
for (i = 0; i < 6; i++)
oled_write_data(ASCII6x8[k][i]); /* 写入一个字节 */
x += 6;
j++;
}
}
/********
* oled init
*/
static int oledinit(void)
{
oled_write_cmd(0xAE); /* 显示关 */
oled_write_cmd(0x40); /* 设置列低位地址 */
oled_write_cmd(0xB0); /* 设置列高位地址 */
oled_write_cmd(0xC8);
oled_write_cmd(0x81);
oled_write_cmd(0xFF);
oled_write_cmd(0xA1);
oled_write_cmd(0xA6);
oled_write_cmd(0xA8);
oled_write_cmd(0x1F);
oled_write_cmd(0xD3);
oled_write_cmd(0x00);
oled_write_cmd(0xD5);
oled_write_cmd(0xF0);
oled_write_cmd(0xD9);
oled_write_cmd(0x22);
oled_write_cmd(0xDA);
oled_write_cmd(0x02);
oled_write_cmd(0xDB);
oled_write_cmd(0x49);
oled_write_cmd(0x8D);
oled_write_cmd(0x14);
oled_write_cmd(0xAF);
return 0;
}
/***************************************************************************************************
*
* 打开设备
*
**************************************************************************************************/
static int oled_open(struct inode *inode, struct file *filp)
{
// oled_write_cmd(0xAE); /* 显示关 */
// oled_write_cmd(0x00); /* 设置列低位地址 */
// oled_write_cmd(0x10); /* 设置列高位地址 */
// oled_write_cmd(0x40); /* set start line address Set Mapping RAM Display Start Line (0x00~0x3F) */
// oled_write_cmd(0x81); /* 设置对比度 */
// oled_write_cmd(0xCF); /* 值越大 越亮 */
// oled_write_cmd(0xA1); /* 设置列左右反置 0xa0左右反置 0xa1正常 */
// oled_write_cmd(0xC8); /* 设置行上下反置 0xc0上下反置 0xc8正常 */
// oled_write_cmd(0xA6); /* 设置正常显示 */
// oled_write_cmd(0x20); /* 设置页地址模式 (0x00/0x01/0x02) */
// oled_write_cmd(0x02); /* 页寻址 */
// oled_write_cmd(0x8D); /* 设置电荷磊开关 */
// oled_write_cmd(0x14); /* 电荷磊开 */
// oled_write_cmd(0xA4); /* 字符显示开关 0xA4：开 0xA5：关 */
// oled_write_cmd(0xA6); /* 背景色显示开关 0xA6:关 0xA7:开 */
// oled_write_cmd(0xAF); /* 显示开 */
oledinit();
oled_clear(); /* 初始清屏 */
oled_pos(0, 0);
printk(KERN_INFO "oled open\n");
return 0;
}
/***************************************************************************************************
*
* Function: oled写函数
* Input : buffer 2个字节 第一个字节oled片内地址0~0xFF，第二个字节为要写入的数据
* size 写数据的长度 两个字节
*
**************************************************************************************************/
static ssize_t oled_write(struct file *filp, const char __user *buffer, size_t size, loff_t *off)
{
// 一共可以显示168字
unsigned char data[168];
copy_from_user(data, buffer, 168);
oled_p6x8str(0, 0, data);
return 0;
}
/*
* oled操作集
*/
static struct file_operations oled_fops = {
.owner = THIS_MODULE,
.write = oled_write,
.open = oled_open,
};
/*
* 当驱动和设备信息匹配成功之后，就会调用probe函数，驱动所有的资源的注册和初始化全部放在probe函数中；
*/
static int oled_probe(struct i2c_client *client, const struct i2c_device_id *i2c_device)
{
int result;
/* 动态分配字符设备编号: (major,0) */
if (alloc_chrdev_region(&devid, 0, 1, "oled") == OK)
{
printk(KERN_INFO "alloc device number : major:[%d], minor:[%d] succeed!\n", MAJOR(devid), MINOR(devid));
}
else
{
printk(KERN_INFO "register device number error!\n");
return ERROR;
}
/* 字符设备初始化以及注册 */
cdev_init(&i2c_cdev, &oled_fops);
cdev_add(&i2c_cdev, devid, 1);
/* 创建类,它会在sys目录下创建/sys/class/oled_class这个类 */
oled_class = class_create(THIS_MODULE, "oled_class");
if (IS_ERR(oled_class))
{
printk("can't create class\n");
return ERROR;
}
/* 在/sys/class/oled_class下创建oled设备，然后mdev通过这个自动创建/dev/oled这个设备节点 */
device_create(oled_class, NULL, devid, NULL, "oled");
printk(KERN_INFO "create device file 'oled' succeed!\n");
/* 保存当前i2c_client */
oled_client = client;
printk(KERN_INFO "get i2c_client, client name = %s, addr = 0x%x\n", oled_client->name, oled_client->addr);
printk(KERN_INFO "get i2c_adapter, adapter name = %s\n", oled_client->adapter->name);
printk(KERN_INFO "oled probe\n");
return 0;
}
/*
* 设备被移除了，或者驱动被卸载了，全部要释放，释放资源的操作就放在该函数中
*/
static int oled_remove(struct i2c_client *client)
{
/* 注销类、以及类设备 /sys/class/oled_class会被移除*/
device_destroy(oled_class, devid);
class_destroy(oled_class);
/* 移除字符设备 */
cdev_del(&i2c_cdev);
/* 注销设备编号 */
unregister_chrdev_region(devid, 1);
printk(KERN_INFO "oled remove\n");
return 0;
}
/*
* oled设备探测到的回调函数
*/
static int oled_detect(struct i2c_client *client, struct i2c_board_info *info)
{
printk(KERN_INFO "oled detect success\n");
// 设置I2C从设备名称 必须要和i2c_driver.idtable里面名称匹配
strcpy(info->type, "oled");
return OK;
}
/* i2c设备id列表 */
static const struct i2c_device_id oled_id[] = {
{"ssd1306", 0},
{} /* 最后一个必须为空,表示结束 */
};
/*
* i2c驱动入口函数
*/
static struct i2c_driver oled_driver = {
.probe = oled_probe,
.remove = oled_remove,
.driver = {
.name = "oled", /* 驱动名称 */
.owner = THIS_MODULE,
},
.address_list = address_list, /* 从设备列表 */
.detect = oled_detect,
.id_table = oled_id, /* id列表 */
.class = I2C_CLASS_HWMON | I2C_CLASS_SPD, /* 内存设备 */
};
/*
*init入口函数
*/
static int __init oled_init(void)
{
i2c_add_driver(&oled_driver); /* 将i2c_driver注册到系统中去 */
printk(KERN_INFO "oled i2c_driver was added into the system.\n");
return 0;
}
/*
* exit出口函数
*/
static void __exit oled_exit(void)
{
i2c_del_driver(&oled_driver);
printk(KERN_INFO "oled i2c_driver was deleted from the system.\n");
return;
}
module_init(oled_init);
module_exit(oled_exit);
MODULE_AUTHOR("rx-ted");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("oled device driver, 2023-07-18");
再建立makefile，如
SDK_DIR = ~/buildroot
KERN_DIR = $(SDK_DIR)/linux_5.10/build/cv1800b_milkv_duo_sd
# app:
# $(CC) -o ssd1306-app ssd1306-app.c
all:
make -C $(KERN_DIR) M=$(PWD) modules
clean:
make -C $(KERN_DIR) M=$(PWD) modules clean
rm -rf modules.order
obj-m += ssd1306.o
这样可以到一个ssd1306.ko文件
传送milkv-duo
将ssd1306.ko传送milkv-duo
scp driver/ssd1306/ssd1306.ko root@192.168.42.1:/mnt/system/ko
进入milkv-duo，这样命令
# 1. lsmod 先看看两个lsmod前后区别
[root@milkv]~# lsmod
Module Size Used by Tainted: GF
cvi_vc_driver 879138 0 [permanent]
cv180x_jpeg 25220 1 cvi_vc_driver,[permanent]
cv180x_vcodec 28451 2 cvi_vc_driver,cv180x_jpeg,[permanent]
cv180x_tpu 32041 0 [permanent]
cv180x_clock_cooling 5953 0 [permanent]
cv180x_thermal 3404 0
cv180x_rgn 100809 0 [permanent]
cv180x_dwa 48669 0 [permanent]
cv180x_vpss 280938 0 [permanent]
cv180x_vi 338826 0 [permanent]
snsr_i2c 9341 0 [permanent]
cvi_mipi_rx 54306 0 [permanent]
cv180x_fast_image 32955 0 [permanent]
cv180x_rtos_cmdqu 25922 1 cv180x_fast_image,[permanent]
cv180x_base 96472 8 cvi_vc_driver,cv180x_rgn,cv180x_dwa,cv180x_vpss,cv180x_vi,snsr_i2c,cvi_mipi_rx,cv180x_rtos_cmdqu,[permanent]
cv180x_sys 64161 7 cvi_vc_driver,cv180x_rgn,cv180x_dwa,cv180x_vpss,cv180x_vi,cv180x_fast_image,cv180x_base,[permanent]
# 2. insmod /mnt/system/ko/ssd1306.ko
[root@milkv]~# insmod /mnt/system/ko/ssd1306.ko
# 3. lsmod
[root@milkv]~# lsmod
Module Size Used by Tainted: GF
ssd1306 5654 0
cvi_vc_driver 879138 0 [permanent]
cv180x_jpeg 25220 1 cvi_vc_driver,[permanent]
cv180x_vcodec 28451 2 cvi_vc_driver,cv180x_jpeg,[permanent]
cv180x_tpu 32041 0 [permanent]
cv180x_clock_cooling 5953 0 [permanent]
cv180x_thermal 3404 0
cv180x_rgn 100809 0 [permanent]
cv180x_dwa 48669 0 [permanent]
cv180x_vpss 280938 0 [permanent]
cv180x_vi 338826 0 [permanent]
snsr_i2c 9341 0 [permanent]
cvi_mipi_rx 54306 0 [permanent]
cv180x_fast_image 32955 0 [permanent]
cv180x_rtos_cmdqu 25922 1 cv180x_fast_image,[permanent]
cv180x_base 96472 8 cvi_vc_driver,cv180x_rgn,cv180x_dwa,cv180x_vpss,cv180x_vi,snsr_i2c,cvi_mipi_rx,cv180x_rtos_cmdqu,[permanent]
cv180x_sys 64161 7 cvi_vc_driver,cv180x_rgn,cv180x_dwa,cv180x_vpss,cv180x_vi,cv180x_fast_image,cv180x_base,[permanent]
# 4. dmesg
[root@milkv]~# dmesg
[ 412.711906] create device file 'oled' succeed!
[ 412.711920] get i2c_client, client name = ssd1306, addr = 0x3c
[ 412.711927] get i2c_adapter, adapter name = Synopsys DesignWare I2C adapter
[ 412.711933] oled probe
[ 412.712132] oled i2c_driver was added into the system.
# 打印 hello ssd1306
[root@milkv]~# echo hello ssd1306 > /dev/oled
^C
[root@milkv]~# echo 1234567890 qwertyuiopasdfghjklzxcvbnm > /dev/oled
^C
演示效果
本文转载自：https://bbs.elecfans.com/jishu_2366537_1_1.html，作者：高敬义