From 65dfd21ef0558722f47c316c9252bd7b74822c6a Mon Sep 17 00:00:00 2001
From: "(Tim) Efthimis Kritikos" <efkf@firemail.cc>
Date: Sat, 9 Dec 2023 00:53:52 +0000
Subject: [PATCH] Peripherals/I2C_driver: Uncommented code to check for device
 acknowledgment

---
 Makefile                                      |  2 +-
 .../OrangeCrab_r0.2.1/testbench.cpp           |  1 +
 system/peripherals/I2C_driver.v               | 20 ++++++++-----------
 3 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/Makefile b/Makefile
index c9961dc..a46a21a 100644
--- a/Makefile
+++ b/Makefile
@@ -62,7 +62,7 @@ upload: boot_code/bios.stxt
 fpga_sim: boot_code/bios.stxt
 	${Q}make ${MAKEOPTS} PRINT_PATH_PREFIX=system/ -C system fpga_sim
 
-.PHONY: fpga
+.PHONY: help
 help:
 	@echo 'Simulation targets:'
 	@echo '                          - No target will start a simulation with the default'
diff --git a/system/fpga_config/OrangeCrab_r0.2.1/testbench.cpp b/system/fpga_config/OrangeCrab_r0.2.1/testbench.cpp
index 99aaf3b..6e96c54 100644
--- a/system/fpga_config/OrangeCrab_r0.2.1/testbench.cpp
+++ b/system/fpga_config/OrangeCrab_r0.2.1/testbench.cpp
@@ -32,6 +32,7 @@ int main(int argc, char** argv) {
 	contextp->commandArgs(argc, argv);
 	system_state = new Vfpga_top{contextp};
 	system_state->user_button=1;
+	system_state->i2c_sda_in=0;
 
 	//system_state->reset=1;
 	tick();
diff --git a/system/peripherals/I2C_driver.v b/system/peripherals/I2C_driver.v
index b9e4554..2c674e8 100644
--- a/system/peripherals/I2C_driver.v
+++ b/system/peripherals/I2C_driver.v
@@ -19,9 +19,7 @@
 
 module I2C_driver (
 	input wire clock,
-/* verilator lint_off UNUSEDSIGNAL */
 	input wire SDA_input,
-/* verilator lint_on UNUSEDSIGNAL */
 	output wire SDA_output,
 	output reg SDA_direction, //1:output 0:input
 	output reg SCL,
@@ -119,13 +117,12 @@ always @(posedge clock) begin
 		end
 		6'b001110:begin
 			SCL<=1;
-		//	if (SDA==1)begin
-		//		led<=1;
-		//		i2c_state<=6'b011111;
-		//	end else begin
+			if (SDA_input==1)begin
+				i2c_state<=6'b111111; //TODO: Don't freeze the entire driver if a single error occurs!! (here and on the second ack as well)
+			end else begin
 				i2c_state<=6'b001111;
 				data_bit_counter<=0;
-		//	end
+			end
 		end
 	/****** separator ********/
 		6'b001111:begin
@@ -192,13 +189,12 @@ always @(posedge clock) begin
 		end
 		6'b011011:begin
 			SCL<=1;
-		//	if (SDA==1)begin
-		//		led<=1;
-		//		i2c_state<=6'b011111;
-		//	end else begin
+			if (SDA_input==1)begin
+				i2c_state<=6'b111111;
+			end else begin
 				i2c_state<=6'b011100;
 				SDA_direction<=1;
-		//	end
+			end
 		end
 	/****** separator ********/
 		6'b011100:begin