一、ST7735介绍

ST7735是一款spi驱动的lcd屏，通过spi发送用于操作lcd的寄存器指令和显示数据

二、ST7735操作模式

当DC引脚为低，命令模式，目的是设置芯片显示参数等

当DC引脚为高，数据模式，发送的数据应该为图像rgb数据，保存在display ram并显示

BLK是控制LCD背光（不开背光，无法显示）

三、ST7735 rgb模式

ST7735有多种数据模式，包含RGB666\RGB444\RGB565等，如下图

四、ST7735 驱动代码-RGB565模式

#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>#define LCD_RESET    _IOW('L',0x1,int)
#define LCD_DCX     _IOW('L',0x2,int)
#define LCD_POWER   _IOW('L',0x3,int)#define GPIO_LOW 0x0000
#define GPIO_HIGH   0x0001#define LCD_HEIGHT    128
#define LCD_WIDTH   160/***************************** command ***************************/#define   ST7735_SleepOut         0x11
#define ST7735_FullColor                0xB1    //in normal mode
#define     ST7735_8Colors          0xB2    //in idle mode
#define ST7735_InPartialMode            0xB3    //
#define     ST7735_INVCTR           0xB4    //display inversion control
#define ST7735_PWCTR1           0xC0    //power control 1
#define ST7735_PWCTR2           0xC1    //power control 2
#define ST7735_PWCTR3           0xC2    //power control 3
#define ST7735_PWCTR4           0xC3    //power control 4
#define ST7735_PWCTR5           0xC4    //power control 5
#define ST7735_VMCTR1           0xC5    //VCOM  control 1
#define ST7735_MADCTL           0x36    //Memory data access control
#define ST7735_GMCTRP1          0xE0    //Gamma '+'polarity Correction characteristics setting
#define ST7735_GMCTRN1          0xE1    //Gamma '-'polarity Correction characteristics setting
#define ST7735_COLMOD           0x3A    //interface pixel format
#define ST7735_CASET            0x2A    //column address set
#define ST7735_RASET            0x2B    //Row Address Set
#define ST7735_RAMWR            0x2C    //Memory write
#define ST7735_DISPON           0x29    //display onstatic int spi_gpio_fd;
static int spi_fd;
static const char *device = "/dev/spidev32766.0";
static const char *spi_gpio_device = "/dev/spi_gpio";static uint32_t mode=SPI_MODE_0;
static uint8_t bits = 8;
static uint32_t speed = 15000000;
static uint16_t delay=0;static void pabort(const char *s)
{perror(s);abort();
}static void transfer(int fd, uint8_t *tx, uint8_t *rx, size_t len)
{int ret;struct spi_ioc_transfer tr = {.tx_buf = (unsigned long)tx,.rx_buf = (unsigned long)rx,.len = len,.delay_usecs = delay,.speed_hz = speed,.bits_per_word = bits,};if (mode & SPI_TX_QUAD)tr.tx_nbits = 4;else if (mode & SPI_TX_DUAL)tr.tx_nbits = 2;if (mode & SPI_RX_QUAD)tr.rx_nbits = 4;else if (mode & SPI_RX_DUAL)tr.rx_nbits = 2;if (!(mode & SPI_LOOP)) {if (mode & (SPI_TX_QUAD | SPI_TX_DUAL))tr.rx_buf = 0;else if (mode & (SPI_RX_QUAD | SPI_RX_DUAL))tr.tx_buf = 0;}ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);if (ret < 1)pabort("can't send spi message");}static void transfer_command(int fd, uint8_t command,size_t len)
{uint8_t value=command;ioctl(spi_gpio_fd, LCD_DCX, GPIO_LOW);transfer(fd,&value,NULL,len);
}static void transfer_command_parameter(int fd, uint8_t parameter,size_t len)
{uint8_t value=parameter;  ioctl(spi_gpio_fd, LCD_DCX, GPIO_HIGH);transfer(fd,&value,NULL,len);
}static void transfer_data(int fd, uint8_t *tx, uint8_t *rx, size_t len)
{ioctl(spi_gpio_fd, LCD_DCX, GPIO_HIGH);transfer(fd,tx,rx,len);
}static void set_window_regs(uint8_t x_start, uint8_t x_end, uint8_t y_start, uint8_t y_end)    //设置需要显示的窗口大小，起始位置
{   uint8_t command=0x00;uint8_t data=0x00;//x方向大小transfer_command(spi_fd, ST7735_CASET, 1);transfer_command_parameter(spi_fd, 0x00,1);transfer_command_parameter(spi_fd, x_start,1);transfer_command_parameter(spi_fd, 0x00,1);transfer_command_parameter(spi_fd, x_end-1,1);//y方向大小transfer_command(spi_fd, ST7735_RASET, 1);transfer_command_parameter(spi_fd, 0x00,1);transfer_command_parameter(spi_fd, y_start,1);transfer_command_parameter(spi_fd, 0x00,1);transfer_command_parameter(spi_fd, y_end-1,1);}
static void clean_window(uint8_t x_start, uint8_t x_end, uint8_t y_start, uint8_t y_end, uint16_t back_color)
{//缓存上色uint8_t rgb[(x_end-x_start)*(y_end-y_start)*2];for(int i=0;i<(x_end-x_start)*(y_end-y_start)*2;i++){if( 0 == i%2){rgb[i]= (back_color & 0xFF00)>>8;}else{rgb[i]= back_color & 0x00FF;}}//开窗口set_window_regs(x_start,x_end,y_start,y_end);//缓存写入显存transfer_command(spi_fd, ST7735_RAMWR, 1);for(int i=0;i<(x_end-x_start);i++){transfer_data(spi_fd, &rgb[i*(y_end-y_start)*2], NULL, (y_end-y_start)*2);}
}
static void spi_lcd_reset(unsigned int value)
{ioctl(spi_gpio_fd, LCD_RESET, value);  //reset芯片
}static void spi_lcd_power(unsigned int value)
{ioctl(spi_gpio_fd, LCD_POWER, value);
}static void spi_init(void)
{int ret;//set spi_moderet = ioctl(spi_fd, SPI_IOC_WR_MODE32, &mode);if (ret == -1)pabort("can't set spi mode");ret = ioctl(spi_fd, SPI_IOC_RD_MODE32, &mode);if (ret == -1)pabort("can't get spi mode");//bits per wordret = ioctl(spi_fd, SPI_IOC_WR_BITS_PER_WORD, &bits);if (ret == -1)pabort("can't set bits per word");ret = ioctl(spi_fd, SPI_IOC_RD_BITS_PER_WORD, &bits);if (ret == -1)pabort("can't get bits per word");//max speed hzret = ioctl(spi_fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);if (ret == -1)pabort("can't set max speed hz");ret = ioctl(spi_fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);if (ret == -1)pabort("can't get max speed hz");printf("spi mode: 0x%x\n", mode);printf("bits per word: %d\n", bits);printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);}static void st7735_lcd_init(void)
{spi_lcd_reset(GPIO_LOW);usleep(1000);spi_lcd_reset(GPIO_HIGH);usleep(1000);transfer_command(spi_fd, ST7735_SleepOut, 1);usleep(100*1000);transfer_command(spi_fd, ST7735_FullColor, 1);    //选择需要调整的参数时是什么类型的transfer_command_parameter(spi_fd, 0x05,1);       //发送芯片参数transfer_command_parameter(spi_fd, 0x3c,1);transfer_command_parameter(spi_fd, 0x3c,1);transfer_command(spi_fd, ST7735_8Colors, 1);transfer_command_parameter(spi_fd, 0x05,1);transfer_command_parameter(spi_fd, 0x3c,1);transfer_command_parameter(spi_fd, 0x3c,1);transfer_command(spi_fd, ST7735_InPartialMode, 1);transfer_command_parameter(spi_fd, 0x05,1);transfer_command_parameter(spi_fd, 0x3c,1);transfer_command_parameter(spi_fd, 0x3c,1);transfer_command_parameter(spi_fd, 0x05,1);transfer_command_parameter(spi_fd, 0x3c,1);transfer_command_parameter(spi_fd, 0x3c,1);transfer_command(spi_fd, ST7735_INVCTR, 1);transfer_command_parameter(spi_fd, 0x03,1);transfer_command(spi_fd, ST7735_PWCTR1, 1);transfer_command_parameter(spi_fd, 0x28,1);transfer_command_parameter(spi_fd, 0x08,1);transfer_command_parameter(spi_fd, 0x04,1);transfer_command(spi_fd, ST7735_PWCTR2, 1);transfer_command_parameter(spi_fd, 0xc0,1);transfer_command(spi_fd, ST7735_PWCTR3, 1);transfer_command_parameter(spi_fd, 0x0d,1);transfer_command_parameter(spi_fd, 0x00,1);transfer_command(spi_fd, ST7735_PWCTR4, 1);transfer_command_parameter(spi_fd, 0x8d,1);transfer_command_parameter(spi_fd, 0x2a,1);transfer_command(spi_fd, ST7735_PWCTR5, 1);transfer_command_parameter(spi_fd, 0x8d,1);transfer_command_parameter(spi_fd, 0xee,1);transfer_command(spi_fd, ST7735_VMCTR1, 1);transfer_command_parameter(spi_fd, 0x1a,1);transfer_command(spi_fd, ST7735_MADCTL, 1);transfer_command_parameter(spi_fd, 0xa0,1);transfer_command(spi_fd, ST7735_GMCTRP1, 1);transfer_command_parameter(spi_fd, 0x04,1);transfer_command_parameter(spi_fd, 0x22,1);transfer_command_parameter(spi_fd, 0x07,1);transfer_command_parameter(spi_fd, 0x0a,1);transfer_command_parameter(spi_fd, 0x2e,1);transfer_command_parameter(spi_fd, 0x30,1);transfer_command_parameter(spi_fd, 0x25,1);transfer_command_parameter(spi_fd, 0x2a,1);transfer_command_parameter(spi_fd, 0x28,1);transfer_command_parameter(spi_fd, 0x26,1);transfer_command_parameter(spi_fd, 0x2e,1);transfer_command_parameter(spi_fd, 0x3a,1);transfer_command_parameter(spi_fd, 0x00,1);transfer_command_parameter(spi_fd, 0x01,1);transfer_command_parameter(spi_fd, 0x03,1);transfer_command_parameter(spi_fd, 0x13,1);transfer_command(spi_fd, ST7735_GMCTRN1, 1);transfer_command_parameter(spi_fd, 0x04,1);transfer_command_parameter(spi_fd, 0x16,1);    transfer_command_parameter(spi_fd, 0x06,1);transfer_command_parameter(spi_fd, 0x0d,1);transfer_command_parameter(spi_fd, 0x2d,1);transfer_command_parameter(spi_fd, 0x26,1);transfer_command_parameter(spi_fd, 0x23,1);transfer_command_parameter(spi_fd, 0x27,1);transfer_command_parameter(spi_fd, 0x27,1);transfer_command_parameter(spi_fd, 0x25,1);transfer_command_parameter(spi_fd, 0x2d,1);transfer_command_parameter(spi_fd, 0x3b,1);transfer_command_parameter(spi_fd, 0x00,1);transfer_command_parameter(spi_fd, 0x01,1);transfer_command_parameter(spi_fd, 0x04,1);transfer_command_parameter(spi_fd, 0x13,1);transfer_command(spi_fd, ST7735_COLMOD, 1);transfer_command_parameter(spi_fd, 0x05,1);transfer_command(spi_fd, ST7735_DISPON, 1);}int main(int argc, char *argv[])
{spi_gpio_fd = open(spi_gpio_device, O_RDWR);if (spi_gpio_fd < 0)pabort("can't open device");spi_fd = open(device, O_RDWR);if (spi_fd < 0)pabort("can't open device");spi_init();st7735_lcd_init();   //LCD芯片初始化clean_window(0, LCD_WIDTH, 0, LCD_HEIGHT, 0xF800);    //设置LCD屏为一种颜色-红色,使用RGB565spi_lcd_power(1);  //LCD屏背光设置sleep(10);close(spi_gpio_fd);close(spi_fd);return 0;
}

结果展示

五、ST7735上点阵字体使用

使用点阵字体主要目的在于降低字体的储存空间，例如下图B字母，8*11大小，只看第一行像素点的信息，11111100转换为字节为0xFC（当然还可以压缩），但转换为显示数据，如RGB565，每一个像素需要用2byte，第一行就占用了16byte的空间

如果需要使用点阵字体，将对应像素点转换为对应的颜色即可，如第一行，显示数据为0x00(rgb565-黑色) 0x00 0x00 0x00 0x00 0x00 0xFF（白色） 0xFF

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