关于数字电位器MCP4022T-103（U/D接口的使用）

问题： 关于数字电位器MCP4022T-103（U/D接口的使用）
描述:

请问谁用过数字电位器MCP4022T-103的？里面的U/D接口咋用？我用单片机模拟，似乎不行，以下是我的单片机代码，求指导。
while(1)
    {
       
        Control_Res_CS_Write(1);
        CyDelay(20);
        Control_Res_CS_Write(0);
        CyDelay(20);
        Control_Res_DA_Write(0);
        CyDelay(20);
        Control_Res_DA_Write(1);
        CyDelay(20);
        Control_Res_DA_Write(0);
        CyDelay(20);
        Control_Res_DA_Write(1);
        CyDelay(20);
        Control_Res_DA_Write(0);
        CyDelay(20);
        Control_Res_DA_Write(1);
        CyDelay(20);
        Control_Res_DA_Write(0);
        CyDelay(20);
        Control_Res_DA_Write(1);
        CyDelay(20);
        Control_Res_CS_Write(1);
        CyDelay(200);
        Control_Res_DA_Write(1);
        CyDelay(1000);
｝