From 2a8e7fefd3243a8950b4fbfe06e38a5f670ccdc2 Mon Sep 17 00:00:00 2001
From: mstroh76 <m.stroh76@gmail.com>
Date: Fri, 31 May 2024 17:49:59 +0200
Subject: [PATCH] #250

---
 wiringPi/pcf8574.c                         |   9 +-
 wiringPi/test/Makefile                     |  27 ++++-
 wiringPi/test/wiringpi_i2c_test1_pcf8574.c | 112 +++++++++++++++++++++
 3 files changed, 141 insertions(+), 7 deletions(-)
 create mode 100644 wiringPi/test/wiringpi_i2c_test1_pcf8574.c

diff --git a/wiringPi/pcf8574.c b/wiringPi/pcf8574.c
index 402257e..61b4cc7 100644
--- a/wiringPi/pcf8574.c
+++ b/wiringPi/pcf8574.c
@@ -1,7 +1,7 @@
 /*
  * pcf8574.c:
  *	Extend wiringPi with the PCF8574 I2C GPIO expander chip
- *	Copyright (c) 2013 Gordon Henderson
+ *	Copyright (c) 2013-2024 Gordon Henderson and contributors
  ***********************************************************************
  * This file is part of wiringPi:
  *	https://github.com/WiringPi/WiringPi/
@@ -33,8 +33,9 @@
 
 /*
  * myPinMode:
- *	The PCF8574 is an odd chip - the pins are effectively bi-directional,
- *	however the pins should be drven high when used as an input pin...
+ *	The PCF8574 is a 8-Bit I/O Expander with Open-drain output.
+ *  The pins are effectively bi-directional,
+ *	however the pins should be driven high when used as an input pin...
  *	So, we're effectively copying digitalWrite...
  *********************************************************************************
  */
@@ -102,7 +103,7 @@ static int myDigitalRead (struct wiringPiNodeStruct *node, int pin)
  * pcf8574Setup:
  *	Create a new instance of a PCF8574 I2C GPIO interface. We know it
  *	has 8 pins, so all we need to know here is the I2C address and the
- *	user-defined pin base.
+ *	user-defined pin base. Default address (A0-A3 low) is 0x20.
  *********************************************************************************
  */
 
diff --git a/wiringPi/test/Makefile b/wiringPi/test/Makefile
index d144baf..cbcd3d8 100644
--- a/wiringPi/test/Makefile
+++ b/wiringPi/test/Makefile
@@ -6,7 +6,9 @@ tests = wiringpi_test1_sysfs wiringpi_test2_sysfs wiringpi_test3_device_wpi wiri
 
 xotests = wiringpi_xotest_test1_spi
 
-all: $(tests) $(xotests)
+i2ctests = wiringpi_i2c_test1_pcf8574
+
+all: $(tests) $(xotests) $(i2ctests)
 
 wiringpi_test1_sysfs: 
 	${CC} ${CFLAGS} wiringpi_test1_sysfs.c -o wiringpi_test1_sysfs -lwiringPi
@@ -32,6 +34,9 @@ wiringpi_test7_version:
 wiringpi_xotest_test1_spi:
 	${CC} ${CFLAGS} wiringpi_xotest_test1_spi.c -o wiringpi_xotest_test1_spi -lwiringPi
 
+wiringpi_i2c_test1_pcf8574:
+	${CC} ${CFLAGS} wiringpi_i2c_test1_pcf8574.c -o wiringpi_i2c_test1_pcf8574 -lwiringPi
+
 test:
 	@error_state=false ; \
 	for t in $(tests) ; do \
@@ -51,7 +56,7 @@ test:
 xotest:
 	@error_state=false ; \
 	for t in $(tests) $(xotests)  ; do \
-		echo === unit test: $${t} === ; \
+		echo === XO unit test: $${t} === ; \
 		time ./$${t} ; \
 		if [ $$? -ne 0 ]; then \
 		  error_state=true ; \
@@ -64,7 +69,23 @@ xotest:
 		echo "\n\e[5mSTD/XO TEST SUCCESS\e[0m\n"; \
 	fi
 
+i2ctest:
+	@error_state=false ; \
+	for t in $(tests) $(i2ctests)  ; do \
+		echo === I2C unit test: $${t} === ; \
+		time ./$${t} ; \
+		if [ $$? -ne 0 ]; then \
+		  error_state=true ; \
+		fi ; \
+		echo  ; echo  ; \
+	done
+	if [ "$$error_state" = true ]; then \
+		echo "\n\e[5mSTD/I2C TEST FAILED\e[0m\n"; \
+	else \
+		echo "\n\e[5mSTD/I2C TEST SUCCESS\e[0m\n"; \
+	fi
+
 clean: 
-	for t in $(tests) $(xotests) ; do \
+	for t in $(tests) $(xotests) $(i2ctests) ; do \
 		rm -fv $${t} ; \
 	done
diff --git a/wiringPi/test/wiringpi_i2c_test1_pcf8574.c b/wiringPi/test/wiringpi_i2c_test1_pcf8574.c
new file mode 100644
index 0000000..19a699f
--- /dev/null
+++ b/wiringPi/test/wiringpi_i2c_test1_pcf8574.c
@@ -0,0 +1,112 @@
+// WiringPi test program: I2C functions (need PCF8574)
+// Compile: gcc -Wall wiringpi_i2c_test1.c -o wiringpi_i2c_test1 -lwiringPi
+
+#include "wpi_test.h"
+#include "pcf8574.h"
+#include "wiringPiI2C.h"
+
+const int pinBase = 1020;
+const int i2cAdress = 0x20;
+
+int ShowAll() {
+  int in;
+  int value = 0;
+
+  printf("pin: 0  1  2  3  4  5  6  7\nval: ");
+  for (int pin=0; pin<=7; ++pin) {
+    in = digitalRead(pinBase + pin);
+    printf("%d  ", in);
+    if(in==HIGH) { value |= (0x01<<pin); }
+  }
+  printf(" = 0x%02X\n", value);
+  return value;
+}
+
+
+void testPin(const char* msg, int fd, int pin , int value) {
+  printf("%s:\n", msg);
+  int in = digitalRead(pinBase + pin);
+  CheckSame("digitalRead", in, value); 
+
+  int expect =  HIGH==value ? (0x1<<pin) : 0;
+  int pinmask = 0x01<<pin;
+  int i2cread = wiringPiI2CRead(fd);
+  CheckSame("wiringPiI2CRead", i2cread & pinmask, expect);
+  //printf("Value = 0x%X\n",i2cread);
+
+  uint8_t i2cvalue = HIGH==value ? 0x00 : 0xFF;
+  int result = wiringPiI2CRawRead(fd, &i2cvalue, 1);
+  CheckSame("wiringPiI2CRawRead result", result, 1);
+  CheckSame("wiringPiI2CRawRead", i2cvalue & pinmask, expect);
+  //printf("Value = 0x%X\n",i2cvalue);
+}
+
+
+int main (void) {
+  int major, minor;
+ 
+  wiringPiVersion(&major, &minor);
+  printf("Testing I2C functions with PCF8574 (WiringPi %d.%d)\n",major, minor);
+  printf("-------------------------------------------------\n\n");
+
+
+  int ret = pcf8574Setup (pinBase, i2cAdress);
+  if (ret!=1) {
+    FailAndExitWithErrno("pcf8574Setup", ret);
+  }
+  int fd = wiringPiI2CSetup (i2cAdress);
+  if (fd<=0) {
+    FailAndExitWithErrno("wiringPiI2CSetup", fd);
+  }
+  CheckSame("I2C fd", fd, 4);
+
+  ShowAll();
+
+  int pin = 3;
+  testPin("Test pin 3 high", fd, pin , HIGH);
+  testPin("Test pin 4 high", fd, pin+1, HIGH);
+
+  digitalWrite(pinBase + pin, LOW);
+  testPin("Test pin 3 low", fd, pin , LOW);
+  testPin("Test pin 4 high", fd, pin+1, HIGH);
+
+  ShowAll();
+
+  digitalWrite(pinBase + pin, HIGH);
+  testPin("Test pin 3 high", fd, pin , HIGH);
+  testPin("Test pin 4 high", fd, pin+1, HIGH);
+
+  ShowAll();
+
+  printf("\nwiringPiI2CReadReg8:\n");
+  int i2cin, expect;
+  i2cin = wiringPiI2CReadReg8(fd, 0x00);
+  expect = ShowAll();
+  CheckSame("all low wiringPiI2CReadReg8", i2cin, expect);
+
+  i2cin = wiringPiI2CReadReg8(fd, 0xFF);
+  expect =ShowAll();
+  CheckSame("all high wiringPiI2CReadReg8", i2cin, expect);
+
+  printf("\nwiringPiI2CReadBlockData:\n");
+  uint8_t value;
+  int result;
+  value = 0xFF;
+  result = wiringPiI2CReadBlockData(fd, 0x00, &value, 1);
+  CheckSame("wiringPiI2CReadBlockData result", result, 1);
+  expect = ShowAll();
+  CheckSame("all high wiringPiI2CReadBlockData", value, expect);
+
+  printf("\n");
+  value = 0x00;
+  result = wiringPiI2CReadBlockData(fd, 0xFF, &value, 1);
+  CheckSame("wiringPiI2CReadBlockData result", result, 1);
+  expect = ShowAll();
+  CheckSame("all low wiringPiI2CReadBlockData", value, expect);
+
+  return UnitTestState();
+}
+
+
+
+