fix

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
 ## [0.4.1] - 2023-09-23
-- Update readme with advanced interrupts insigts
+- Update readme with advanced interrupts insights
   - kudos to ddowling for testing.
   - add example
 - fix URL examples

README.md

@@ -11,7 +11,7 @@
 
 # PCF8574
 
-Arduino library for PCF8574 - 8 channel I2C IO expander
+Arduino library for PCF8574 - 8 channel I2C IO expander.
 
 
 ## Description
@@ -53,8 +53,8 @@ or in the write mode at the acknowledge bit after the high-to-low transition of
 So there are three scenarios how the INT is reset.
 
 1. pins revert to original state (lesser known).
-2. read from PCF8574 (well known)
-3. write to PCF8574 (well known)
+2. read from the device (well known)
+3. write to the device (well known)
 
 This implies that polling the PCF8574 can miss an INT in scenario 1. (see #48)
 In practice if you have faster polling than your signals changes this would not
@@ -229,7 +229,8 @@ It is advised to use pull-up or pull-down resistors so the lines have a defined
 
 #### Must
 
-- keep in sync with PCF8575
+- update documentation.
+- keep in sync with PCF8575  (as far as meaningful)
 
 #### Should
 
@@ -249,3 +250,4 @@ donate through PayPal or GitHub sponsors.
 
 Thank you,
 
+

examples/PCF8574_performance/PCF8574_performance.ino

@@ -12,6 +12,8 @@ PCF8574 PCF(0x38);
 
 uint32_t start, stop;
 
+volatile uint8_t x;
+
 
 void setup()
 {
@@ -27,12 +29,12 @@ void setup()
   delay(100);  //  time to flush Serial 
 
 
-  for (long clk = 100000; clk < 800000; clk += 100000)
+  for (long clk = 100000; clk < 800000; clk += 50000)
   {
     //  setup and measure
     Wire.setClock(clk);
     start = micros();
-    int x = PCF.read8();
+    x = PCF.read8();
     stop = micros();
 
     //  output results
@@ -62,3 +64,4 @@ void loop()
 
 
 //  -- END OF FILE --
+