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RGB666RGB444RGB565等，如下图
四、ST7735 驱动代码-RGB565模式#include#include #include #include #include #include #include #include #include #include #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 #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 on static 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_mode ret = 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 word ret = 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 hz ret = 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%xn", mode); printf("bits per word: %dn", 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RGB565 spi_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
