He's using a PCF8574 port expander which is driven from one of the mbed's I2C busses, which is on pins p9 and p10.
He wants to turn a LED on when a button is pushed. The button is connected to P4 on the port expander; the LED is attached to pin 5.
Here's the breadboarded circuit under manual test :)
And here's the code:
#include "mbed.h" #include "PCF8574.h" PCF8574 io(p9,p10,0x40); int main() { while(1) { io.write(0x30); if ((io.read() & 0x20) == 0) { io.write(0x20); } } }
Thanks for sharing this :)
ReplyDeleteJust what i needed to get another 6 GPIO's !
Thanks,
Theo
http://mbed.org/users/ekelmans/