Sync I2CKeyPad 0.5.0

README.md

@@ -59,6 +59,38 @@ It might take some trying to get the correct pins connected.
 ```
 
 
+## I2C
+
+### I2C addresses
+
+This library uses a PCF8575 chip.
+
+|  Type      |  Address-range  |  Notes                    |
+|:-----------|:---------------:|:-------------------------:|
+|  PCF8575   |  0x20 to 0x27   |  same range as PCF8574 !  |
+
+Be careful to select an unique I2C address for every device on the bus.
+
+
+### I2C multiplexing
+
+Sometimes you need to control more devices than possible with the default
+address range the device provides.
+This is possible with an I2C multiplexer e.g. TCA9548 which creates up
+to eight channels (think of it as I2C subnets) which can use the complete
+address range of the device.
+
+Drawback of using a multiplexer is that it takes more administration in
+your code e.g. which device is on which channel.
+This will slow down the access, which must be taken into account when
+deciding which devices are on which channel.
+Also note that switching between channels will slow down other devices
+too if they are behind the multiplexer.
+
+- https://github.com/RobTillaart/TCA9548
+
+
+
 ## Interface
 
 ```cpp

examples/I2Ckeypad8x8_demo01/I2Ckeypad8x8_demo01.ino

@@ -13,7 +13,7 @@
 #include "Wire.h"
 #include "I2CKeyPad8x8.h"
 
-const uint8_t KEYPAD_ADDRESS = 0x38;
+const uint8_t KEYPAD_ADDRESS = 0x20;
 
 I2CKeyPad8x8 keyPad(KEYPAD_ADDRESS);