关键词：RISC-V 开发板、RVB2601、WiFi&BLE，低功耗，玄铁 E906,AliOS Things，RISC-V MCU，上手 好用，控制，开关
1. 前言
基于 RVB2601 的 GUI 程序是利用 Lvgl 开源组件实现在 OLED 屏幕上的字符和图形显示。开发者可以利用 Lvgl 组件在 OLED 屏幕上实现 Label 控件显示功能。
建议在看本文之前，先详细看下RVB2601资源。本例程名为 ch2601_gui_demo，可以通过 CDK 直接从 OCC 拉取。
2. 硬件配置
2.1 显示屏
RVB2601 开发板采用的是 OLED 显示屏， 位于开发板正面。
2.2 屏幕物理接口
CH2601 开发板采用单彩色图形显示面板，屏幕分辨率 128x64 pixel，屏幕背景颜色可选，该程序中采用的是一块黄色背景的屏幕。屏幕控制器采用 SSD1309，通过 4 wire SPI 接口与主芯片连接, 原理图如下所示, 对应的 pin 引脚分别为 PA27、PA28、PA29、PA30。 原理图如下：
软件通过对 SPI 进行读写操作来实现对 OLED 屏上的像素进行点操作，从而实现整个屏的点亮操作。
3. GUI 软件开发
3.1 LVGL 介绍
LVGL 全称 Light and Versatile Graphics Library,是一个自由的，开源的 GUI 库，具有界面精美，资源消耗小，可移植度高, 响应式布局等特点, 全库采用纯 c 语言开发.
主要特性如下.
具有非常丰富的内置控件,像 buttons, charts, lists, sliders, images 等
高级图形效果：动画，反锯齿，透明度，平滑滚动
支持多种输入设备,像 touchpad, mouse, keyboard, encoder 等
支持多语言的 UTF-8 编码
支持多个和多种显示设备，例如同步显示在多个彩色屏或单色屏上
完全自定制的图形元素
硬件独立于任何微控制器或显示器
可以缩小到最小内存 (64 kB Flash, 16 kB RAM)
支持操作系统、外部储存和 GPU（非必须）
仅仅单个帧缓冲设备就可以呈现高级视觉特效
使用 C 编写以获得最大兼容性(兼容 C++)
支持 PC 模拟器
为加速 GUI 设计,提供教程,案例和主题,支持响应式布局
提供了在线和离线文档
基于自由和开源的 MIT 协议
支持 MicroPython
3.2 例程下载
打开 CDK，点击 HOME 图标，查找 ch2601_gui_demo 后，打开工程可以看到以下目录：
3.3 LVGL 移植接口
Lvgl 移植代码位于 app/src/lvgl_porting 文件夹内，其包含 oled.c 和 oled.h。
以下功能接口位于 app/src/lvgl_porting/oled.c， 实现 SPI 管脚的初始化，主要针对 CS, DATA, CLOCK, DATAIN 管脚，同时实现了对不同管脚的读写操作。
static void oled_gpio_init(){ // csi_gpio_pin_init(&pin_clk, PA28); csi_gpio_pin_dir(&pin_clk, GPIO_DIRECTION_OUTPUT); csi_gpio_pin_init(&pin_mosi, PA29); csi_gpio_pin_dir(&pin_mosi, GPIO_DIRECTION_OUTPUT); csi_gpio_pin_init(&pin_cs, PA27); csi_gpio_pin_dir(&pin_cs, GPIO_DIRECTION_OUTPUT); csi_gpio_pin_init(&pin_miso, PA30); //dc csi_gpio_pin_dir(&pin_miso, GPIO_DIRECTION_OUTPUT);}static void lcd_cs(uint8_t d){ if (d == 1) { csi_gpio_pin_write(&pin_cs, GPIO_PIN_HIGH); } else { csi_gpio_pin_write(&pin_cs, GPIO_PIN_LOW); }}static void lcd_dc(uint8_t d){ if (d == 1) { csi_gpio_pin_write(&pin_miso, GPIO_PIN_HIGH); } else { csi_gpio_pin_write(&pin_miso, GPIO_PIN_LOW); }}static void lcd_sclk(uint8_t d){ if (d == 1) { csi_gpio_pin_write(&pin_clk, GPIO_PIN_HIGH); } else { csi_gpio_pin_write(&pin_clk, GPIO_PIN_LOW); }}static void lcd_sdin(uint8_t d){ if (d == 1) { csi_gpio_pin_write(&pin_mosi, GPIO_PIN_HIGH); } else { csi_gpio_pin_write(&pin_mosi, GPIO_PIN_LOW); }}
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void Write_Command(unsigned char Data){ unsigned char i; lcd_cs(0); lcd_dc(0); for (i = 0; i < 8; i++) { lcd_sclk(0); lcd_sdin((Data & 0x80) >> 7); Data = Data << 1; lcd_sclk(1); } lcd_dc(1); lcd_cs(1);}void Write_Data(unsigned char Data){ unsigned char i; lcd_cs(0); lcd_dc(1); for (i = 0; i < 8; i++) { lcd_sclk(0); lcd_sdin((Data & 0x80) >> 7); Data = Data << 1; lcd_sclk(1); } lcd_dc(1); lcd_cs(1);}
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void Set_Start_Column(unsigned char d){ Write_Command(0x00 + d % 16); // Set Lower Column Start Address for Page Addressing Mode // Default => 0x00 Write_Command(0x10 + d / 16); // Set Higher Column Start Address for Page Addressing Mode // Default => 0x10}void Set_Addressing_Mode(unsigned char d){ Write_Command(0x20); // Set Memory Addressing Mode Write_Command(d); // Default => 0x02 // 0x00 => Horizontal Addressing Mode // 0x01 => Vertical Addressing Mode // 0x02 => Page Addressing Mode}void Set_Column_Address(unsigned char a, unsigned char b){ Write_Command(0x21); // Set Column Address Write_Command(a); // Default => 0x00 (Column Start Address) Write_Command(b); // Default => 0x7F (Column End Address)}void Set_Page_Address(unsigned char a, unsigned char b){ Write_Command(0x22); // Set Page Address Write_Command(a); // Default => 0x00 (Page Start Address) Write_Command(b); // Default => 0x07 (Page End Address)}void Set_Start_Line(unsigned char d){ Write_Command(0x40 | d); // Set Display Start Line // Default => 0x40 (0x00)}void Set_Contrast_Control(unsigned char d){ Write_Command(0x81); // Set Contrast Control for Bank 0 Write_Command(d); // Default => 0x7F}void Set_Segment_Remap(unsigned char d){ Write_Command(d); // Set Segment Re-Map // Default => 0xA0 // 0xA0 => Column Address 0 Mapped to SEG0 // 0xA1 => Column Address 0 Mapped to SEG127}void Set_Entire_Display(unsigned char d){ Write_Command(d); // Set Entire Display On / Off // Default => 0xA4 // 0xA4 => Normal Display // 0xA5 => Entire Display On}void Set_Inverse_Display(unsigned char d){ Write_Command(d); // Set Inverse Display On/Off // Default => 0xA6 // 0xA6 => Normal Display // 0xA7 => Inverse Display On}void Set_Multiplex_Ratio(unsigned char d){ Write_Command(0xA8); // Set Multiplex Ratio Write_Command(d); // Default => 0x3F (1/64 Duty)}void Set_Display_On_Off(unsigned char d){ Write_Command(d); // Set Display On/Off // Default => 0xAE // 0xAE => Display Off // 0xAF => Display On}void Set_Start_Page(unsigned char d){ Write_Command(0xB0 | d); // Set Page Start Address for Page Addressing Mode // Default => 0xB0 (0x00)}void Set_Common_Remap(unsigned char d){ Write_Command(d); // Set COM Output Scan Direction // Default => 0xC0 // 0xC0 => Scan from COM0 to 63 // 0xC8 => Scan from COM63 to 0}void Set_Display_Offset(unsigned char d){ Write_Command(0xD3); // Set Display Offset Write_Command(d); // Default => 0x00}void Set_Display_Clock(unsigned char d){ Write_Command(0xD5); // Set Display Clock Divide Ratio / Oscillator Frequency Write_Command(d); // Default => 0x70 // D[3:0] => Display Clock Divider // D[7:4] => Oscillator Frequency}void Set_Low_Power(unsigned char d){ Write_Command(0xD8); // Set Low Power Display Mode Write_Command(d); // Default => 0x04 (Normal Power Mode)}void Set_Precharge_Period(unsigned char d){ Write_Command(0xD9); // Set Pre-Charge Period Write_Command(d); // Default => 0x22 (2 Display Clocks [Phase 2] / 2 Display Clocks [Phase 1]) // D[3:0] => Phase 1 Period in 1~15 Display Clocks // D[7:4] => Phase 2 Period in 1~15 Display Clocks}void Set_Common_Config(unsigned char d){ Write_Command(0xDA); // Set COM Pins Hardware Configuration Write_Command(d); // Default => 0x12 // Alternative COM Pin Configuration // Disable COM Left/Right Re-Map}void Set_NOP(){ Write_Command(0xE3); // Command for No Operation}void Set_Command_Lock(unsigned char d){ Write_Command(0xFD); // Set Command Lock Write_Command(d); // Default => 0x12 // 0x12 => Driver IC interface is unlocked from entering command. // 0x16 => All Commands are locked except 0xFD.}
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static void oled_initialize(){ Set_Command_Lock(0x12); // Unlock Driver IC (0x12/0x16) Set_Display_On_Off(0xAE); // Display Off (0xAE/0xAF) Set_Display_Clock(0xA0); // Set Clock as 116 Frames/Sec Set_Multiplex_Ratio(0x3F); // 1/64 Duty (0x0F~0x3F) Set_Display_Offset(0x00); // Shift Mapping RAM Counter (0x00~0x3F) Set_Start_Line(0x00); // Set Mapping RAM Display Start Line (0x00~0x3F) Set_Low_Power(0x04); // Set Normal Power Mode (0x04/0x05) Set_Addressing_Mode(0x02); // Set Page Addressing Mode (0x00/0x01/0x02) Set_Segment_Remap(0xA1); // Set SEG/Column Mapping (0xA0/0xA1) Set_Common_Remap(0xC8); // Set COM/Row Scan Direction (0xC0/0xC8) Set_Common_Config(0x12); // Set Alternative Configuration (0x02/0x12) Set_Contrast_Control(Brightness); // Set SEG Output Current Set_Precharge_Period(0x82); // Set Pre-Charge as 8 Clocks & Discharge as 2 Clocks Set_VCOMH(0x34); // Set VCOM Deselect Level Set_Entire_Display(0xA4); // Disable Entire Display On (0xA4/0xA5) Set_Inverse_Display(0xA6); // Disable Inverse Display On (0xA6/0xA7) Fill_RAM(0x00); // Clear Screen Set_Display_On_Off(0xAF); // Display On (0xAE/0xAF)}
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static void gui_label_create(void){ lv_obj_t *p = lv_label_create(lv_scr_act(), NULL); lv_label_set_long_mode(p, LV_LABEL_LONG_BREAK); lv_label_set_align(p, LV_LABEL_ALIGN_CENTER); lv_obj_set_pos(p, 0, 4); lv_obj_set_size(p, 128, 60); lv_label_set_text(p, "THEAD RISC-V\nGUI\nDEMO");}
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3.4. 编译运行
编译通过后，点击下载，下载成功后复位运行。可看屏上显示"THEAD RISC-V\nGUI\nDEMO" 字符串。
4. 总结
本例程介绍了如何通过 SPI 接口来实现对 OLED 屏幕的图形显示。后续还有更多的开发例程，敬请期待！
本文转自平头哥芯片开放社区（occ），更多详情请点击https://occ.t-head.cn/store/board?channelName=1。
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