ST7796 LCD Controller driver（ST7796液晶控制器驱动程序）
Overview（概览）
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The ST7796S is a single-chip controller/driver for 262K-color, graphic type TFT-LCD. It consists of 960 source lines and 480 gate lines driving circuits. The ST7796S is capable of connecting directly to an external microprocessor, and accepts 8-bit/9-bit/16-bit/18-bit parallel interface, SPI, and the ST7796S also provides MIPI interface. Display data can be stored in the on-chip display data RAM of 320x480x18 bits. It can perform display data RAM read-/write-operation with no external clock to minimize power consumption. In addition, because of the integrated power supply circuit necessary to drive liquid crystal; it is possible to make a display system with fewest components.
The ST7796 LCD controller driver is a platform-agnostic driver, based on the generic MIPI driver. It implements display initialization, supports display rotation and implements the display flush callback. The user needs to implement only two platform-specific functions to send a command or pixel data to the controller via SPI or parallel bus. Typically these are implemented by calling the appropriate SDK library functions on the given platform.
ST7796S 是一款用于262K色彩图形式TFT-LCD的单芯片控制器/驱动器。它具有960行源和480行网驱动电路。ST7796S能够直接连接到外部微处理器，并接受8位/9位/16位/18位并行接口、SPI以及MIPI接口。显示数据可以存储在320x480x18位的片内显示数据RAM中。它可以在没有外部时钟的情况下执行显示数据RAM读/写操作，以最小化功耗。此外，由于集成了驱动液晶所需的电源电路，可以使用最少的组件构建显示系统。
ST7796 LCD驱动器 driver is a platform-agnostic driver, based on the generic MIPI driver 是一个与平台无关的驱动器，基于通用MIPI驱动器。它实现了显示初始化，支持显示旋转，并实现了显示刷新回调函数。用户只需实现两个特定于平台的函数，通过SPI或并行总线向控制器发送命令或像素数据。通常情况下，通过在给定平台上调用适当的SDK库函数来实现这些函数。
Prerequisites（先决条件）
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There are no prerequisites.
没有先决条件。
Configuring the driver（配置驱动程序）
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Enable the ST7796 driver support in lv_conf.h, by cmake compiler define or by KConfig
#define LV_USE_ST7796 1
在lv_conf.h中启用ST7796驱动程序支持，可以通过CMake编译器定义或通过KConfig来实现。
#define LV_USE_ST7796 1
Usage（用法）
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You need to implement two platform-dependent functions:
/* Send short command to the LCD. This function shall wait until the transaction finishes. */
int32_t my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
...
}
/* Send large array of pixel data to the LCD. If necessary, this function has to do the byte-swapping. This function can do the transfer in the background. */
int32_t my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
...
}
To create an ST7796-based display use the function
/**
* Create an LCD display with ST7796 driver
* @param hor_res horizontal resolution
* @param ver_res vertical resolution
* @param flags default configuration settings (mirror, RGB ordering, etc.)
* @param send_cmd platform-dependent function to send a command to the LCD controller (usually uses polling transfer)
* @param send_color platform-dependent function to send pixel data to the LCD controller (usually uses DMA transfer: must implement a 'ready' callback)
* @return pointer to the created display
*/
lv_display_t * lv_st7796_create(uint32_t hor_res, uint32_t ver_res, lv_lcd_flag_t flags,
lv_st7796_send_cmd_cb_t send_cmd_cb, lv_st7796_send_color_cb_t send_color_cb);
For additional details and a working example see the generic MIPI driver documentation.
你需要实现两个与平台相关的函数：
/* Send short command to the LCD. This function shall wait until the transaction finishes. */
int32_t my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
...
}
/* Send large array of pixel data to the LCD. If necessary, this function has to do the byte-swapping. This function can do the transfer in the background. */
int32_t my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
...
}
使用以下函数创建基于ST7796驱动器的显示屏：
/**
* Create an LCD display with ST7796 driver
* @param hor_res horizontal resolution
* @param ver_res vertical resolution
* @param flags default configuration settings (mirror, RGB ordering, etc.)
* @param send_cmd platform-dependent function to send a command to the LCD controller (usually uses polling transfer)
* @param send_color platform-dependent function to send pixel data to the LCD controller (usually uses DMA transfer: must implement a 'ready' callback)
* @return pointer to the created display
*/
lv_display_t * lv_st7796_create(uint32_t hor_res, uint32_t ver_res, lv_lcd_flag_t flags,
lv_st7796_send_cmd_cb_t send_cmd_cb, lv_st7796_send_color_cb_t send_color_cb);
有关更多详细信息和可行示例，请参阅 通用MIPI驱动程序文档.