写一段fpga的iic驱动OLED初始化程序

在FPGA上为IIC总线驱动 OLED显示设备，首先需要了解基本的IIC通信协议，并熟悉所使用的OLED模块的接口。以下是一个简化的示例，假设我们使用的是Microchip的SAMD21单片机作为主控制器，并通过PDIOS外设支持IIC，同时使用SSD1306作为OLED显示。

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity iic_oled_driver is
    Port (
        SDA : in OUT STD_LOGIC;
        SCL : in OUT STD_LOGIC;
        RST : in OUT STD_LOGIC; -- OLED reset signal
        OLED_ADDR : in STD_LOGIC_VECTOR (7 downto 0); -- OLED address bus
        OLED_DATA : inout STD_LOGIC_VECTOR (15 downto 0) -- OLED data bus
    );
end iic_oled_driver;

architecture Behavioral of iic_oled_driver is
    constant OLED_I2C_SPEED : time := 100 ns; -- Set IIC speed

begin
    process (SDA, SCL)
    begin
        -- 初始化过程
        SCL <= '0'; -- Set SCL low for start condition
        wait for OLED_I2C_SPEED / 2; -- OLED地址设定
        for i in OLED_ADDR'range loop
            if i = 0 then
                SDA <= '0';
            else
                SDA <= '1';
            end if;
            wait for OLED_I2C_SPEED;
        end loop;
        
        SDA <= '0'; -- Write device address
        wait for OLED_I2C_SPEED;
        SCL <= '1'; -- 启动命令序列，如初始化、亮度设置等
        OLED_DATA <= X"00"; -- Command register
        SDA <= '1'; -- Write command
        wait for OLED_I2C_SPEED;
        OLED_DATA <= X"80"; -- Set display mode and contrast
        SDA <= '1';
        wait for OLED_I2C_SPEED;
        
        -- 清屏和亮度设置等
        OLED_DATA <= X"01"; -- Page address
        SDA <= '1';
        wait for OLED_I2C_SPEED;
        
        -- 结束条件
        SDA <= '0';
        wait for OLED_I2C_SPEED;
        SDA <= '1';
        wait for OLED_I2C_SPEED / 2; -- Stop condition delay
        SCL <= '0';
    end process;
    
    -- OLED复位
    process(RST)
    begin
        if rising_edge(RST) then
            SDA <= '0'; -- Reset the OLED
            wait for 500 ns; -- Hold reset for duration
            SDA <= '1'; -- Release reset
        end if;
    end process;
end Behavioral;