RVB2601应用开发实战系列三: GUI图形显示
本帖最后由 sky 于 2021-5-4 21:25 编辑1. 前言
基于RVB2601的GUI程序是利用Lvgl开源组件实现在OLED屏幕上做字符和图形显示。开发者可以利用Lvgl组件在OLED屏幕上实现Label空间显示功能。
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屏上的像素进行点缀操作，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);
}
}
[*]以下功能函数位于app/src/lvgl_porting/oled.c，通过SPI实现对屏幕的命令和数据写操作。
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);
}
[*]以下功能函数位于app/src/lvgl_porting/oled.c，实现对屏幕的基本命令操作，例如设置屏幕行列地址，屏幕的亮度控制等。
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 => Display Clock Divider
// D => 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 / 2 Display Clocks )
// D => Phase 1 Period in 1~15 Display Clocks
// D => 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.
}
[*]该功能函数位于app/src/lvgl_porting/oled.c，实现对屏幕的初始化。
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)
}
[*]该功能函数位于app/src/main.c，实现在屏幕固定处画一个label, 显示一串字符串。
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");
}
3.4. 编译运行
编译通过后，点击下载成功，复位运行。可看屏上显示"THEAD RISC-V\nGUI\nDEMO" 字符串。
5. 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！
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