// rtl program for i2c_gpio.v `define P0_P9_OP 4'b1010 //0x0A //`define P0_P3_OP 4'b1011 //0x0B `define P0_P3_OP 4'b0111 //0x07 `define P4_P7_OP 4'b1110 //0xE0 //`define P8_P9_OP 4'b1101 //0x0D module i2c_gpio(clk, cs, sr_in, sda_out, sr_out, gpio); input clk,cs; input sr_in; output sda_out; output sr_out; output [7:0] gpio; reg [7:0] sr; reg [7:0] addrreg; reg sda_out; reg sr_out ; reg [7:0] gpio; reg [7:0] ram; wire [3:0] addr; wire [3:0] data; assign addr = sr[3:0]; assign data = sr[7:4]; always@(posedge clk) begin if (cs == 1'b0) begin sr_out <= sr[7]; sr[7:1] <= sr[6:0]; sr[0] <= sr_in; end begin if (addr[0] == 1'b0) // low bit zero - start bit begin if(addr[3:0] == 4'h0E) // 0xD is the address of the slave begin sda_out = 1'b1; // high bit for Acknowledge to master if(addr[3]== 1'b1) // high bit for write begin case (addr[3:0]) // data[3:0] for data write // `P0_P9_OP : gpio[7:4] <= {sr[0], sr[1], sr[2], sr[3], sr[4], sr[5], sr[6], sr[7]}; `P0_P3_OP : gpio[3:0] <= {data[0], data[1], data[2], data[3]}; `P4_P7_OP : gpio[3:0] <= {data[3], data[2], data[1], data[0]}; // `P8_P9_OP : gpio[9:8] <= {sr[0], sr[0]}; // default : gpio[7:0] <= {sr[0], sr[0], sr[0], sr[0], // sr[0], sr[0], sr[0], sr[0]}; endcase sda_out = 1'b1; // high bit for Acknowledge master end else begin sda_out = 1'bz; end end end end end endmodule