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【嵌入式】强行写GPIO实现I2C通讯,控制SSD1306显示屏显示图像

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2014-1-26
发表于 2017-11-19 09:59:26 | 显示全部楼层 |阅读模式

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SSD1306显示屏的PDF文档:https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf

这玩意儿是一个128x64分辨率(其实它有三种规格,我买的是这种)、单色、自带显存的玩意儿。它的接口有很多种,我买的是封装成i2c接口的。
控制它显示的原理很简单:开屏,写显存。完事儿。写显存后它就会立即把效果显示出来。当然它自己是有个刷新率的,会以一定频率不断读取显存并使用屏幕显示。
除了显存,它还有各种控制寄存器。和之前的用i2c操作MPU6050的情况不同,用i2c操作SSD1306的方式分为两种:

1、写命令
2、写显存

其中写命令的方式,PDF文档描述得不是很清楚,而官方资料居然是C艹的,它写了个C艹的类用于维护SSD1306,令人恼火。
不过这个C艹的资料也还算好懂。经过一次次尝试我知道了它是如何写命令和写显存的了。

写命令的方式:
1、开始条件。这个和之前的例子一样,最初SDA和SCL都是高电平,然后先拉低SDA,再拉低SCL。
2、写入芯片地址,以及R/W位。控制SSD1306不存在读取的过程,所以R/W位设为0,也就是低电平——写入。
3、从SSD1306读取ACK状态。不过SSD1306的SDA输出的pin不一定和I2C总线相连,所以它也可能不回应ACK。
4、写入控制字节。第7 bit是Continuation bit,不管它,写0。第6 bit是“命令/数据”bit,值为1的时候是写显存,值为0是写命令。其余位都是0。所以这次写入的控制字节其实是0。
5、读取ACK。
6、写入命令。
7、读取ACK。
8、结束条件:先拉高SCL,再拉高SDA。

当一个命令带有参数的时候,你要先用一次这种写命令的过程写入你的命令字节,再用一次这种写命令的过程写入你的命令参数。

写显存的方式:
1、开始条件。
2、芯片地址。
3、读取ACK。
4、写入控制字节。因为是写显存操作,这次写入的控制字节是0x40。
5、读取ACK。
6、写入你要写进显存的值。你写入后,它自己会把写显存的指针往后移,移动到结尾后又会归位到起始处。
7、读取ACK。
8、回到第6步。嗯其实这是个循环,你可以在此完成批量的写显存的操作,想写几个字节就写几个字节。
9、结束条件。

写显存的过程受到多个控制寄存器的影响。按照我这次写的代码对其进行的初始化的情况来看,你写入的一个字节,会成为它的显示指针所在的当前位置向下8个像素的状态值。然后它的显示指针是往右移动1个字节的。显示指针移动到最右后,又会自动移回最左,然后往下移动8个像素。这种设计,是为了便于让你通过直接写显存的方式来让它一行行地输出8个像素高的点阵字体。
不过你也可以把SSD1306_MEMORYMODE设为1(先发送命令“SSD1306_MEMORYMODE”(值为0x20),再发送命令“1”),来让它改变显示指针的移动行为——之前是向右移动1个像素,现在是向下移动8个像素。然后就可以构成一个从顶到下为x轴,从左到右为y轴的单色位图了。

这次的测试发现_i2c_delay()里面的usleep非常影响I2C的传输效率,它延迟的时长可能远超5us。估计和Bananapi M2的性能与时间片长度的设定有关。切走CPU会导致写入一整个显存要耗费接近1秒的时间。我把usleep(5)注释掉后,我发现它依然能完成通讯,并且显示屏的更新效率变得很高了。
[C] 纯文本查看 复制代码
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<stdarg.h>
#include<inttypes.h>
#include<wiringPi.h>
#include<unistd.h>

#define param_pins int scl_pin, int sda_pin
#define i2c_pin scl_pin, sda_pin

static void _i2c_delay()
{
	// usleep(5);
	// 不用延迟它也能实现效果
	// 用了延迟反而变得贼慢
}

static void _i2c_start(param_pins)
{
	pinMode(scl_pin, OUTPUT);
	pinMode(sda_pin, OUTPUT);
	
	// start condition
	digitalWrite(scl_pin, HIGH);
	_i2c_delay();
	digitalWrite(sda_pin, HIGH);
	_i2c_delay();
	digitalWrite(sda_pin, LOW);
	_i2c_delay();
	digitalWrite(scl_pin, LOW);
	_i2c_delay();
}

static void _i2c_stop(param_pins)
{
	pinMode(scl_pin, OUTPUT);
	pinMode(sda_pin, OUTPUT);
	
	digitalWrite(scl_pin, LOW);
	digitalWrite(sda_pin, HIGH);
	_i2c_delay();
	digitalWrite(scl_pin, HIGH);
	_i2c_delay();
}

static void _i2c_send_bit(param_pins, const int value)
{
	digitalWrite(sda_pin, value ? HIGH : LOW);
	digitalWrite(scl_pin, HIGH);
	_i2c_delay();
	digitalWrite(scl_pin, LOW);
	_i2c_delay();
}

static int _i2c_read_bit(param_pins)
{
	int received;
	digitalWrite(scl_pin, HIGH);
	_i2c_delay();
	received = digitalRead(sda_pin) == HIGH ? 1 : 0;
	digitalWrite(scl_pin, LOW);
	_i2c_delay();
	return received;
}

static int _i2c_read_byte(param_pins)
{
	int received = 0;
	
	pinMode(scl_pin, OUTPUT);
	pinMode(sda_pin, INPUT);
	
	received |= _i2c_read_bit(i2c_pin) << 7;
	received |= _i2c_read_bit(i2c_pin) << 6;
	received |= _i2c_read_bit(i2c_pin) << 5;
	received |= _i2c_read_bit(i2c_pin) << 4;
	received |= _i2c_read_bit(i2c_pin) << 3;
	received |= _i2c_read_bit(i2c_pin) << 2;
	received |= _i2c_read_bit(i2c_pin) << 1;
	received |= _i2c_read_bit(i2c_pin);
	
	// send NACK
	pinMode(sda_pin, OUTPUT);
	_i2c_send_bit(i2c_pin, 1);
	return received;
}

static void _i2c_write_byte(param_pins, const int value)
{
	pinMode(scl_pin, OUTPUT);
	pinMode(sda_pin, OUTPUT);
	_i2c_send_bit(i2c_pin, value & 0x80 ? 1 : 0);
	_i2c_send_bit(i2c_pin, value & 0x40 ? 1 : 0);
	_i2c_send_bit(i2c_pin, value & 0x20 ? 1 : 0);
	_i2c_send_bit(i2c_pin, value & 0x10 ? 1 : 0);
	_i2c_send_bit(i2c_pin, value & 0x08 ? 1 : 0);
	_i2c_send_bit(i2c_pin, value & 0x04 ? 1 : 0);
	_i2c_send_bit(i2c_pin, value & 0x02 ? 1 : 0);
	_i2c_send_bit(i2c_pin, value & 0x01 ? 1 : 0);
}

#define BLACK 0
#define WHITE 1
#define INVERSE 2

#define SSD1306_I2C_ADDRESS   0x3C  // 011110+SA0+RW - 0x3C or 0x3D
// Address for 128x32 is 0x3C
// Address for 128x64 is 0x3D (default) or 0x3C (if SA0 is grounded)

/*=========================================================================
    SSD1306 Displays
    -----------------------------------------------------------------------
    The driver is used in multiple displays (128x64, 128x32, etc.).
    Select the appropriate display below to create an appropriately
    sized framebuffer, etc.

    SSD1306_128_64  128x64 pixel display

    SSD1306_128_32  128x32 pixel display

    SSD1306_96_16

    -----------------------------------------------------------------------*/
   #define SSD1306_128_64
//   #define SSD1306_128_32
//   #define SSD1306_96_16
/*=========================================================================*/

#if defined SSD1306_128_64 && defined SSD1306_128_32
  #error "Only one SSD1306 display can be specified at once in SSD1306.h"
#endif
#if !defined SSD1306_128_64 && !defined SSD1306_128_32 && !defined SSD1306_96_16
  #error "At least one SSD1306 display must be specified in SSD1306.h"
#endif

#if defined SSD1306_128_64
  #define SSD1306_LCDWIDTH                  128
  #define SSD1306_LCDHEIGHT                 64
#endif
#if defined SSD1306_128_32
  #define SSD1306_LCDWIDTH                  128
  #define SSD1306_LCDHEIGHT                 32
#endif
#if defined SSD1306_96_16
  #define SSD1306_LCDWIDTH                  96
  #define SSD1306_LCDHEIGHT                 16
#endif

#define SSD1306_SETCONTRAST 0x81
#define SSD1306_DISPLAYALLON_RESUME 0xA4
#define SSD1306_DISPLAYALLON 0xA5
#define SSD1306_NORMALDISPLAY 0xA6
#define SSD1306_INVERTDISPLAY 0xA7
#define SSD1306_DISPLAYOFF 0xAE
#define SSD1306_DISPLAYON 0xAF

#define SSD1306_SETDISPLAYOFFSET 0xD3
#define SSD1306_SETCOMPINS 0xDA

#define SSD1306_SETVCOMDETECT 0xDB

#define SSD1306_SETDISPLAYCLOCKDIV 0xD5
#define SSD1306_SETPRECHARGE 0xD9

#define SSD1306_SETMULTIPLEX 0xA8

#define SSD1306_SETLOWCOLUMN 0x00
#define SSD1306_SETHIGHCOLUMN 0x10

#define SSD1306_SETSTARTLINE 0x40

#define SSD1306_MEMORYMODE 0x20
#define SSD1306_COLUMNADDR 0x21
#define SSD1306_PAGEADDR   0x22

#define SSD1306_COMSCANINC 0xC0
#define SSD1306_COMSCANDEC 0xC8

#define SSD1306_SEGREMAP 0xA0

#define SSD1306_CHARGEPUMP 0x8D

#define SSD1306_EXTERNALVCC 0x1
#define SSD1306_SWITCHCAPVCC 0x2

// Scrolling #defines
#define SSD1306_ACTIVATE_SCROLL 0x2F
#define SSD1306_DEACTIVATE_SCROLL 0x2E
#define SSD1306_SET_VERTICAL_SCROLL_AREA 0xA3
#define SSD1306_RIGHT_HORIZONTAL_SCROLL 0x26
#define SSD1306_LEFT_HORIZONTAL_SCROLL 0x27
#define SSD1306_VERTICAL_AND_RIGHT_HORIZONTAL_SCROLL 0x29
#define SSD1306_VERTICAL_AND_LEFT_HORIZONTAL_SCROLL 0x2A

#define stop_if_nack 1
#define ignore_nack 0

typedef struct ssd1306_i2c_ctrl_struct
{
	int sda_pin;
	int scl_pin;
	int chip_addr;
	int check_ack;
}ssd1306_i2c_ctrl_t, *ssd1306_i2c_ctrl_p;

void ssd1306_i2c_init(ssd1306_i2c_ctrl_p inst, param_pins, const int chip_addr, const int check_ack)
{
	memset(inst, 0, sizeof *inst);
	
	inst->sda_pin = sda_pin;
	inst->scl_pin = scl_pin;
	inst->chip_addr = chip_addr;
	inst->check_ack = check_ack;
}

int ssd1306_i2c_send_command(ssd1306_i2c_ctrl_p inst, const int command)
{
	int num_ack = 0;
	const int sda_pin = inst->sda_pin;
	const int scl_pin = inst->scl_pin;
	
	// start condition
	_i2c_start(i2c_pin);
	
	// address & R/W bit (write => 0)
	_i2c_write_byte(i2c_pin, (inst->chip_addr << 1));
	
	// ACK
	pinMode(sda_pin, INPUT);
	if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	
	// control bvte
	_i2c_write_byte(i2c_pin, 0x00);
	
	// ACK
	pinMode(sda_pin, INPUT);
	if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	
	// command
	_i2c_write_byte(i2c_pin, command);
	
	// ACK
	pinMode(sda_pin, INPUT);
	if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	
	// stop condition
	_i2c_stop(i2c_pin);
	return num_ack;
}

int ssd1306_i2c_send_data(ssd1306_i2c_ctrl_p inst, const void *data, const size_t cb_data)
{
	int num_ack = 0;
	const uint8_t *ptr = data;
	size_t counter = cb_data;
	const int sda_pin = inst->sda_pin;
	const int scl_pin = inst->scl_pin;
	
	// start condition
	_i2c_start(i2c_pin);
	
	// address & R/W bit (write => 0)
	_i2c_write_byte(i2c_pin, (inst->chip_addr << 1));
	
	// ACK
	pinMode(sda_pin, INPUT);
	if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	
	// control bvte
	_i2c_write_byte(i2c_pin, 0x40);
	
	// ACK
	pinMode(sda_pin, INPUT);
	if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	
	
	while(counter--)
	{
		// data
		_i2c_write_byte(i2c_pin, *ptr++);
		
		// ACK
		pinMode(sda_pin, INPUT);
		if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	}
	
	// stop condition
	_i2c_stop(i2c_pin);
	return num_ack;
}

int ssd1306_i2c_fill(ssd1306_i2c_ctrl_p inst, const uint8_t val, const size_t cb_len)
{
	int num_ack = 0;
	size_t counter = cb_len;
	const int sda_pin = inst->sda_pin;
	const int scl_pin = inst->scl_pin;
	
	// start condition
	_i2c_start(i2c_pin);
	
	// address & R/W bit (write => 0)
	_i2c_write_byte(i2c_pin, (inst->chip_addr << 1));
	
	// ACK
	pinMode(sda_pin, INPUT);
	if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	
	// control bvte
	_i2c_write_byte(i2c_pin, 0x40);
	
	// ACK
	pinMode(sda_pin, INPUT);
	if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	
	while(counter--)
	{
		// data
		_i2c_write_byte(i2c_pin, val);
		
		// ACK
		pinMode(sda_pin, INPUT);
		if(_i2c_read_bit(i2c_pin)){if(inst->check_ack)return 0;}else num_ack ++;
	}
	
	// stop condition
	_i2c_stop(i2c_pin);
	return num_ack;
}

int ssd1306_i2c_boot(ssd1306_i2c_ctrl_p inst)
{
	int num_ack = 0;
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_DISPLAYOFF);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SETDISPLAYCLOCKDIV);
	num_ack += ssd1306_i2c_send_command(inst, 0xF0);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SETMULTIPLEX);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_LCDHEIGHT - 1);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SETDISPLAYOFFSET);
	num_ack += ssd1306_i2c_send_command(inst, 0);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SETSTARTLINE | 0);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_CHARGEPUMP);
	num_ack += ssd1306_i2c_send_command(inst, 0x14);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_MEMORYMODE);
	num_ack += ssd1306_i2c_send_command(inst, 0);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SEGREMAP | 0x1);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_COMSCANDEC);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SETCOMPINS);
	num_ack += ssd1306_i2c_send_command(inst, 0x12);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SETCONTRAST);
	num_ack += ssd1306_i2c_send_command(inst, 0xCF);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SETPRECHARGE);
	num_ack += ssd1306_i2c_send_command(inst, 0xF1);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_SETVCOMDETECT);
	num_ack += ssd1306_i2c_send_command(inst, 0x40);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_DISPLAYALLON_RESUME);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_NORMALDISPLAY);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_DEACTIVATE_SCROLL);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_DISPLAYON);
	
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_COLUMNADDR);
	num_ack += ssd1306_i2c_send_command(inst, 0);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_LCDWIDTH - 1);
	num_ack += ssd1306_i2c_send_command(inst, SSD1306_PAGEADDR);
	num_ack += ssd1306_i2c_send_command(inst, 0); // Page start address (0 = reset)
#if SSD1306_LCDHEIGHT == 64
	num_ack += ssd1306_i2c_send_command(inst, 7); // Page end address
#endif
#if SSD1306_LCDHEIGHT == 32
	num_ack += ssd1306_i2c_send_command(inst, 3); // Page end address
#endif
#if SSD1306_LCDHEIGHT == 16
	num_ack += ssd1306_i2c_send_command(inst, 1); // Page end address
#endif
	return num_ack;
}

int ssd1306_i2c_cls(ssd1306_i2c_ctrl_p inst)
{
	return ssd1306_i2c_fill(inst, 0, SSD1306_LCDWIDTH * SSD1306_LCDHEIGHT / 8);
}

#include"font8x8.h"

int ssd1306_i2c_putchar(ssd1306_i2c_ctrl_p inst, const int ch)
{
	int v = ch - 1;
	if(v >= 0x7F)v = 0;
	return ssd1306_i2c_send_data(inst, &ascii8x8_vert[v * 8], 8);
}

void ssd1306_i2c_printf(ssd1306_i2c_ctrl_p inst, const char *format, ...)
{
	va_list ap;
	char buf[4096];
	int i;
	
	va_start(ap, format);
	
	vsnprintf(buf, sizeof buf, format, ap);
	
	for(i = 0; i < sizeof buf; i++)
	{
		if(!buf[i])
			break;
		if(buf[i] >= 0x20)
			ssd1306_i2c_putchar(inst, buf[i]);
	}
	
	va_end(ap);
}

#define I2C_GPIO_PIN 9, 8

int main()
{
	wiringPiSetup();
	
	ssd1306_i2c_ctrl_t ssd1306;
	
	ssd1306_i2c_init(&ssd1306, I2C_GPIO_PIN, SSD1306_I2C_ADDRESS, ignore_nack);
	ssd1306_i2c_boot(&ssd1306);
	ssd1306_i2c_cls(&ssd1306);
	
	ssd1306_i2c_printf(&ssd1306, "Hello motherfucker ");
	
	
	sleep(1);
	
	//printf("%d\n", ssd1306_i2c_send_command(&ssd1306, SSD1306_DISPLAYOFF));
	
	return 0;
}

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2014-1-26
 楼主| 发表于 2017-11-19 10:03:43 | 显示全部楼层
点阵字体:
[C] 纯文本查看 复制代码
const unsigned char ascii8x8_vert[] =
{
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,

	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00,
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, //  

	0x00,0x00,0x00,0x00,0x2F,0x00,0x00,0x00, // !
	0x00,0x00,0x03,0x00,0x03,0x00,0x00,0x00, // "
	0x00,0x14,0x3E,0x14,0x3E,0x14,0x00,0x00, // #
	0x00,0x00,0x24,0x2A,0x7F,0x2A,0x12,0x00, // $
	0x02,0x05,0x15,0x0A,0x14,0x2A,0x28,0x10, // %
	0x00,0x00,0x16,0x29,0x29,0x11,0x10,0x28, // &
	0x00,0x00,0x00,0x00,0x03,0x00,0x00,0x00, // '
	0x00,0x00,0x0C,0x12,0x21,0x00,0x00,0x00, // (
	0x00,0x00,0x00,0x21,0x12,0x0C,0x00,0x00, // )
	0x00,0x00,0x15,0x0E,0x1F,0x0E,0x15,0x00, // *
	0x00,0x00,0x08,0x08,0x3E,0x08,0x08,0x00, // +
	0x00,0x00,0x00,0x40,0x20,0x00,0x00,0x00, // ,
	0x00,0x00,0x08,0x08,0x08,0x08,0x00,0x00, // -
	0x00,0x00,0x00,0x00,0x20,0x00,0x00,0x00, // .
	0x00,0x20,0x10,0x08,0x04,0x02,0x01,0x00, // /
	0x00,0x0C,0x12,0x21,0x21,0x12,0x0C,0x00, // 0

	0x00,0x00,0x00,0x22,0x3F,0x20,0x00,0x00, // 1
	0x00,0x22,0x31,0x29,0x29,0x25,0x22,0x00, // 2
	0x00,0x12,0x21,0x29,0x29,0x25,0x12,0x00, // 3
	0x00,0x18,0x14,0x12,0x3F,0x10,0x00,0x00, // 4
	0x00,0x17,0x25,0x25,0x25,0x25,0x19,0x00, // 5
	0x00,0x1E,0x25,0x25,0x25,0x25,0x18,0x00, // 6
	0x00,0x21,0x11,0x09,0x05,0x03,0x01,0x00, // 7
	0x00,0x1A,0x25,0x25,0x25,0x25,0x1A,0x00, // 8
	0x00,0x06,0x29,0x29,0x29,0x29,0x1E,0x00, // 9
	0x00,0x00,0x00,0x00,0x24,0x00,0x00,0x00, // :
	0x00,0x00,0x00,0x40,0x24,0x00,0x00,0x00, // ;
	0x00,0x08,0x08,0x14,0x14,0x22,0x22,0x00, // <
	0x00,0x14,0x14,0x14,0x14,0x14,0x14,0x00, // =
	0x00,0x22,0x22,0x14,0x14,0x08,0x08,0x00, // >
	0x00,0x02,0x01,0x29,0x09,0x06,0x00,0x00, // ?
	0x18,0x24,0x42,0xBA,0xAA,0xBE,0x00,0x00, // @

	0x00,0x30,0x0C,0x0B,0x0B,0x0C,0x30,0x00, // A
	0x00,0x3F,0x25,0x25,0x25,0x1A,0x00,0x00, // B
	0x0C,0x12,0x21,0x21,0x21,0x12,0x00,0x00, // C
	0x00,0x3F,0x21,0x21,0x21,0x1E,0x00,0x00, // D
	0x00,0x3F,0x25,0x25,0x25,0x21,0x00,0x00, // E
	0x00,0x3F,0x05,0x05,0x05,0x01,0x00,0x00, // F
	0x0C,0x12,0x21,0x29,0x29,0x1A,0x00,0x00, // G
	0x00,0x3F,0x04,0x04,0x04,0x04,0x3F,0x00, // H
	0x00,0x00,0x21,0x21,0x3F,0x21,0x21,0x00, // I
	0x00,0x10,0x20,0x21,0x21,0x1F,0x00,0x00, // J
	0x00,0x3F,0x08,0x0C,0x12,0x21,0x00,0x00, // K
	0x00,0x3F,0x20,0x20,0x20,0x20,0x20,0x00, // L
	0x00,0x3F,0x02,0x04,0x08,0x04,0x02,0x3F, // M
	0x00,0x3F,0x02,0x04,0x08,0x10,0x3F,0x00, // N
	0x00,0x00,0x1E,0x21,0x21,0x21,0x1E,0x00, // O
	0x00,0x3F,0x05,0x05,0x05,0x02,0x00,0x00, // P

	0x00,0x00,0x1E,0x21,0x21,0x21,0x5E,0x00, // Q
	0x00,0x3F,0x05,0x0D,0x15,0x22,0x00,0x00, // R
	0x00,0x00,0x12,0x25,0x29,0x29,0x12,0x00, // S
	0x00,0x01,0x01,0x01,0x3F,0x01,0x01,0x01, // T
	0x00,0x1F,0x20,0x20,0x20,0x20,0x1F,0x00, // U
	0x01,0x06,0x18,0x20,0x20,0x18,0x06,0x01, // V
	0x00,0x3F,0x10,0x08,0x04,0x08,0x10,0x3F, // W
	0x00,0x21,0x12,0x0C,0x0C,0x12,0x21,0x00, // X
	0x00,0x01,0x02,0x04,0x38,0x04,0x02,0x01, // Y
	0x00,0x21,0x31,0x29,0x25,0x23,0x21,0x00, // Z
	0x00,0x00,0x3F,0x21,0x21,0x00,0x00,0x00, // [
	0x00,0x01,0x02,0x04,0x08,0x10,0x20,0x00, // \ bs
	0x00,0x00,0x21,0x21,0x3F,0x00,0x00,0x00, // ]
	0x00,0x00,0x02,0x01,0x02,0x00,0x00,0x00, // ^
	0x00,0x20,0x20,0x20,0x20,0x20,0x20,0x00, // _
	0x00,0x00,0x00,0x01,0x02,0x00,0x00,0x00, // `

	0x00,0x10,0x2A,0x2A,0x2A,0x1A,0x3C,0x00, // a
	0x00,0x3F,0x14,0x24,0x24,0x24,0x18,0x00, // b
	0x00,0x00,0x18,0x24,0x24,0x24,0x00,0x00, // c
	0x00,0x18,0x24,0x24,0x24,0x14,0x3F,0x00, // d
	0x00,0x1C,0x2A,0x2A,0x2A,0x2A,0x0C,0x00, // e
	0x00,0x00,0x08,0x3E,0x0A,0x00,0x00,0x00, // f
	0x00,0x18,0xA4,0xA4,0x88,0x7C,0x00,0x00, // g
	0x00,0x00,0x3F,0x04,0x04,0x38,0x00,0x00, // h
	0x00,0x00,0x00,0x00,0x3D,0x00,0x00,0x00, // i
	0x00,0x80,0x80,0x84,0x7D,0x00,0x00,0x00, // j
	0x00,0x00,0x3F,0x10,0x28,0x24,0x00,0x00, // k
	0x00,0x00,0x00,0x3F,0x20,0x00,0x00,0x00, // l
	0x00,0x3C,0x04,0x08,0x08,0x04,0x3C,0x00, // m
	0x00,0x00,0x3C,0x08,0x04,0x04,0x3C,0x00, // n
	0x00,0x18,0x24,0x24,0x24,0x24,0x18,0x00, // o
	0x00,0xFC,0x28,0x24,0x24,0x24,0x18,0x00, // p

	0x00,0x18,0x24,0x24,0x24,0x28,0xFC,0x00, // q
	0x00,0x00,0x3C,0x08,0x04,0x04,0x08,0x00, // r
	0x00,0x00,0x24,0x2A,0x2A,0x12,0x00,0x00, // s
	0x00,0x00,0x04,0x3E,0x24,0x04,0x00,0x00, // t
	0x00,0x00,0x1C,0x20,0x20,0x10,0x3C,0x00, // u
	0x00,0x0C,0x10,0x20,0x20,0x10,0x0C,0x00, // v
	0x0C,0x30,0x20,0x10,0x10,0x20,0x30,0x0C, // w
	0x00,0x24,0x28,0x10,0x10,0x28,0x24,0x00, // x
	0x00,0x84,0x88,0x50,0x20,0x10,0x0C,0x00, // y
	0x00,0x00,0x24,0x34,0x2C,0x24,0x00,0x00, // z
	0x00,0x00,0x0C,0x3F,0x21,0x21,0x00,0x00, // {
	0x00,0x00,0x00,0x00,0x7F,0x00,0x00,0x00, // |
	0x00,0x00,0x21,0x21,0x3F,0x0C,0x00,0x00, // }
	0x00,0x10,0x08,0x08,0x10,0x10,0x08,0x00, // ~
	0x00,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x00, // 
	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, //
};

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发表于 2017-11-19 19:31:31 | 显示全部楼层
与硬件同步交互在使用延迟时要尽量避免使用 yield 延迟,如果需要使用延迟首先选择“计数锁”

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 楼主| 发表于 2017-11-19 22:30:17 | 显示全部楼层
Ayala 发表于 2017-11-19 19:31
与硬件同步交互在使用延迟时要尽量避免使用 yield 延迟,如果需要使用延迟首先选择“计数锁” ...

主要是不想忙等待

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发表于 2017-12-12 20:29:47 | 显示全部楼层
0xAA55 发表于 2017-11-19 22:30
主要是不想忙等待

处理器和硬件交互 经常需要忙等 就算目标硬件控制器支持队列 也很多时候需要等待几tsc 或者等待几晶刻

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