RGB565 显示图片异常

发布于 2022-05-06 11:45:04 浏览：854 订阅该版

[tocm]

### ART-Pi Smart 上使用 RGB565 模式显示，部分时候会出问题

#### 从节省内存空间的角度，我将 lcd 驱动修改为 RGB565 模式，目前测试发现显示图片的时候，部分地方图片像素显示异常：
![](https://s3.bmp.ovh/imgs/2022/05/06/bac666d49049277d.jpg)
正常的图片是这样的：
![](https://s3.bmp.ovh/imgs/2022/05/06/33f86f4218ff3443.jpg)
#### 我使用一个 RGB 的图片显示看是正常的
![](https://s3.bmp.ovh/imgs/2022/05/06/0a8f50da3e779fe8.jpg)
原始图片：
![](https://s3.bmp.ovh/imgs/2022/05/06/13d666bfcf226ff4.jpg)

#### 针对这 lcd 驱动，我做的修改：
``` diff
diff --git a/kernel/bsp/imx6ull-artpi-smart/drivers/drv_lcd.c b/kernel/bsp/imx6ull-artpi-smart/drivers/drv_lcd.c
index c159e47..eca54a2 100644
--- a/kernel/bsp/imx6ull-artpi-smart/drivers/drv_lcd.c
+++ b/kernel/bsp/imx6ull-artpi-smart/drivers/drv_lcd.c
@@ -6,7 +6,7 @@
  * Change Logs:
  * Date           Author       Notes
  * 2021-01-11     Lyons        first version
- * 2021-06-24     RiceChen     refactor
+ * 2021-06-24     RiceChen     refactor * 重构 *
  * 2021-07-28     songchao     add cmd
  */
 
@@ -14,8 +14,8 @@
 #include <rtdevice.h>
 
 #ifdef BSP_USING_LCD
-
-#define LOG_TAG              "drv.lcd"
+#define LOG_LVL  LOG_LVL_DBG
+#define LOG_TAG  "drv.lcd"
 #include <drv_log.h>
 
 #include "fsl_iomuxc.h"
@@ -176,7 +176,9 @@ int rt_hw_elcd_init(void)
 
     _lcd_obj.config = &_lcd_config;
 
+	/* 申请虚拟内存 */
     _lcd_obj.fb_virt = rt_pages_alloc(rt_page_bits(LCD_BUF_SIZE));
+	/* 获取物理地址 */
     _lcd_obj.fb_phy = _lcd_obj.fb_virt + PV_OFFSET;
 
     LOG_D("fb address => 0x%08x\n", _lcd_obj.fb_phy);
@@ -188,8 +190,9 @@ int rt_hw_elcd_init(void)
 
     _lcd_obj.info.width          = LCD_WIDTH;
     _lcd_obj.info.height         = LCD_HEIGHT;
-    _lcd_obj.info.pixel_format   = RTGRAPHIC_PIXEL_FORMAT_RGB888;
+    _lcd_obj.info.pixel_format   = RTGRAPHIC_PIXEL_FORMAT_RGB565;
     _lcd_obj.info.bits_per_pixel = LCD_BITS_PER_PIXEL;
+	/* 关联 frame buffer 首地址 */
     _lcd_obj.info.framebuffer    = (void *)_lcd_obj.fb_virt;
 
     _lcd_obj.parent.type = RT_Device_Class_Graphic;
@@ -209,11 +212,11 @@ int rt_hw_elcd_init(void)
 
     ret = rt_device_register(&_lcd_obj.parent, _lcd_obj.config->name, RT_DEVICE_FLAG_RDWR);
 
-    /* LCD_BL */
+    /* LCD_BL GPIO1_8*/
     rt_pin_mode(IMX6ULL_LCD_BL_PIN, PIN_MODE_OUTPUT);
     rt_pin_write(IMX6ULL_LCD_BL_PIN, PIN_HIGH);
 
-    rt_memset((rt_uint8_t *)_lcd_obj.fb_virt, 0xff, LCD_BUF_SIZE);
+    rt_memset((rt_uint8_t *)_lcd_obj.fb_virt, 0x00, LCD_BUF_SIZE);
 
     return ret;
 }

```
请问可能是什么原因呢？

4 个回答

iysheng 2022-05-06

这家伙很懒，什么也没写！

解决了，是控制器配置问题，具体的 diff 如：
```diff
diff --git a/kernel/bsp/imx6ull-artpi-smart/libraries/sdk/devices/MCIMX6Y2/drivers/fsl_elcdif.c b/kernel/bsp/imx6ull-artpi-smart/libraries/sdk/devices/MCIMX6Y2/drivers/fsl_elcdif.c
index f0a6f0a..bcca7b3 100644
--- a/kernel/bsp/imx6ull-artpi-smart/libraries/sdk/devices/MCIMX6Y2/drivers/fsl_elcdif.c
+++ b/kernel/bsp/imx6ull-artpi-smart/libraries/sdk/devices/MCIMX6Y2/drivers/fsl_elcdif.c
@@ -66,7 +66,7 @@ elcdif_pixel_format_reg_t s_pixelFormatReg[] = {
      LCDIF_CTRL1_BYTE_PACKING_FORMAT(0x0FU)},
     /* kELCDIF_PixelFormatRGB565 */
     {/* Register CTRL. */
-     LCDIF_CTRL_WORD_LENGTH(0U) | LCDIF_CTRL_DATA_FORMAT_16_BIT(1U),
+     LCDIF_CTRL_WORD_LENGTH(0U) | LCDIF_CTRL_DATA_FORMAT_16_BIT(0U),
      /* Register CTRL1. */
      LCDIF_CTRL1_BYTE_PACKING_FORMAT(0x0FU)},
     /* kELCDIF_PixelFormatRGB666 */
```
根据 imx6ull 手册描述， RGB 565 时，需要设置：
![2022-05-06_16-39.png](https://oss-club.rt-thread.org/uploads/20220506/89da3cc8f5fb2afdcfd3550c043aebc6.png.webp)
**BIT3 DATA_FORMAT_16_BIT 需要设置为 0**，**但是使用 [dbg_mm 小工具](https://club.rt-thread.org/ask/article/2ab0433d97511154.html)查看确是 1**：
![2022-05-06_16-30.png](https://oss-club.rt-thread.org/uploads/20220506/166e8ad67683ae3fe699a4957a0f8b7f.png)
后续跟进排查发现在 ``kernel/bsp/imx6ull-artpi-smart/libraries/sdk/devices/MCIMX6Y2/drivers/fsl_elcdif.c`` 文件中定义错了。修改之后就正常了：
![1031580196.jpg](https://oss-club.rt-thread.org/uploads/20220506/9ab1d4b49aada064221ccb8798971b8c.jpg.webp)

谢谢大家积极帮助我解决问题。😊