I2C器件接口IP核的CPLD设计

IF Cmd_reg2 OR Cmd_reg3 THEN

SDA = SDA_tmp; --开始传送数据

SCL = GND;

St = t1;

ELSE

St = t0;

END IF;

WHEN t1 =>

SCL = VCC;

SDA = SDA_tmp;

St = t1a;

WHEN t1a =>

SCL = VCC;

SDA = SDA_tmp;

St = t2;

WHEN t2 =>

Sh_reg[7..1] = Sh_reg[6..0]; --数据左移，取高位

Sh_reg[0] = GND;

Sh_reg[].ena = EXU;

SCL = GND;

SDA = SDA_tmp;

IF Bit[] == 7 THEN --若8位传完，则发应答位；否则继续

St = t3;

ELSE

St = t0;

END IF;

WHEN t3 => --发应答位

SDA =GND;

St = t4;

WHEN t4 =>

SDA = GND;

SCL = VCC;

St = t4a;

WHEN t4a =>

SDA = GND;

SCL = VCC;

St = t5;

WHEN t5 =>

SCL = GND;

St = t6;

WHEN t6 =>

SDA = GND;

FINISHED = VCC;

St = t0;

END CASE;