Test PCF8574 chips with leds

Dependencies:   mbed PCF8574

Revision:
0:759957225002
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/PCF8574.lib	Mon Jul 22 01:29:04 2019 +0000
@@ -0,0 +1,1 @@
+https://os.mbed.com/users/Bas/code/PCF8574/#7913586369c2