From 26210be9509418b0a373cf0c1ada7d3be672fc12 Mon Sep 17 00:00:00 2001
From: "(Tim) Efthimis Kritikos" <efkf@firemail.cc>
Date: Mon, 4 Dec 2023 22:40:53 +0000
Subject: [PATCH] Peripherals/I2C_driver: Corrected the implementation of the
 bidirectional SDA pin, fixing the final yosys 0.35 warning

---
 .../fpga_config/OrangeCrab_r0.2.1/fpga_top.v  | 22 ++++++++++++++++---
 system/peripherals/I2C_driver.v               | 17 +++++++-------
 2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/system/fpga_config/OrangeCrab_r0.2.1/fpga_top.v b/system/fpga_config/OrangeCrab_r0.2.1/fpga_top.v
index 88db6cb..13de6e8 100644
--- a/system/fpga_config/OrangeCrab_r0.2.1/fpga_top.v
+++ b/system/fpga_config/OrangeCrab_r0.2.1/fpga_top.v
@@ -411,14 +411,15 @@ pcf8574_for_HD44780 PCF8574_driver(
 
 // I2C driver
 
-wire SCL,SDA,I2C_BUSY,I2C_SEND;
+wire SCL,SDA_input,SDA_output,SDA_direction,I2C_BUSY,I2C_SEND;
 assign gpio_1=SCL;
-assign gpio_0=SDA;
 
 I2C_driver i2c_driver(
 	.clock(I2C_SPEED),
 
-	.SDA_(SDA),
+	.SDA_input(SDA_input),
+	.SDA_output(SDA_output),
+	.SDA_direction(SDA_direction),
 	.SCL(SCL),
 
 	.address(7'h27),
@@ -427,4 +428,19 @@ I2C_driver i2c_driver(
 	.i2c_data(i2c_data)
 );
 
+TRELLIS_IO #(
+	// Parameters.
+	.DIR ("BIDIR")
+) TRELLIS_IO_00 (
+	// pin
+	.B (gpio_0),
+	//input
+	.I (1'd0),
+	//Direction
+	.T (~( SDA_direction & (~SDA_output) )),
+	// Output
+	.O (SDA_input)
+);
+
+
 endmodule
diff --git a/system/peripherals/I2C_driver.v b/system/peripherals/I2C_driver.v
index 5e53c0a..96a012c 100644
--- a/system/peripherals/I2C_driver.v
+++ b/system/peripherals/I2C_driver.v
@@ -19,7 +19,9 @@
 
 module I2C_driver (
 	input wire clock,
-	inout wire SDA_,
+	input wire SDA_input,
+	output wire SDA_output,
+	output reg SDA_direction, //1:output 0:input
 	output reg SCL,
 
 	input wire [6:0] address,
@@ -30,8 +32,7 @@ module I2C_driver (
 
 reg SDA;
 
-reg i2c_bus_dir=0;
-assign SDA_=(i2c_bus_dir==0)?SDA:1'bz;
+assign SDA_output=SDA;
 
 reg [5:0] i2c_state = 6'b100100;
 
@@ -43,7 +44,7 @@ always @(posedge clock) begin
 	case (i2c_state)
 	/***** start sequence ******/
 		6'b000000:begin
-			i2c_bus_dir<=0;
+			SDA_direction<=1;
 			SDA<=1;
 			SCL<=1;
 			i2c_state<=6'b000001;
@@ -103,7 +104,7 @@ always @(posedge clock) begin
 	/****** Acknowledge ********/
 		6'b001011:begin
 			SCL<=0;
-			i2c_bus_dir<=1;
+			SDA_direction<=0;
 			i2c_state<=6'b001100;
 		end
 		6'b001100:begin
@@ -152,7 +153,7 @@ always @(posedge clock) begin
 	/****** Send data ********/
 		6'b010100:begin
 			SCL<=0;
-			i2c_bus_dir<=0;
+			SDA_direction<=1;
 			i2c_state<=6'b010101;
 		end
 		6'b010101:begin
@@ -175,7 +176,7 @@ always @(posedge clock) begin
 		end
 	/****** Acknowledge ********/
 		6'b011000:begin
-			i2c_bus_dir<=1;
+			SDA_direction<=0;
 			SCL<=0;
 			i2c_state<=6'b011001;
 		end
@@ -194,7 +195,7 @@ always @(posedge clock) begin
 		//		i2c_state<=6'b011111;
 		//	end else begin
 				i2c_state<=6'b011100;
-				i2c_bus_dir<=0;
+				SDA_direction<=1;
 		//	end
 		end
 	/****** separator ********/