Diff: main.cpp

Revision:

0:addc96275da2

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Oct 15 21:25:53 2012 +0000
@@ -0,0 +1,46 @@
+/*Program Example 7.5: I2C Master, transfers switch state to second mbed acting as slave, and displays state of slave's switches on its leds.
+                                                                              */
+#include "mbed.h"
+I2C i2c_port(p9, p10);     //Configure a serial port, pins 9 and 10 are sda, scl
+DigitalOut red_led(p25);   //red led
+DigitalOut green_led(p26); //green led
+DigitalIn  switch_ip1(p5); //input switch
+DigitalIn  switch_ip2(p6);
+
+char switch_word ;        //word we will send
+char recd_val;            //value received from slave
+const int addr = 0x52;    //the I2C slave address, an arbitrary even number
+
+int main() {
+  while(1) {
+    switch_word=0xa0;                    //set up a recognisable output pattern
+    if (switch_ip1==1)
+      switch_word=switch_word|0x01;      //OR in lsb
+    if (switch_ip2==1)
+      switch_word=switch_word|0x02;      //OR in next lsb
+    //send a single byte of data, in correct I2C package
+    i2c_port.start();                    //force a start condition
+    i2c_port.write(addr);                //send the address
+    i2c_port.write(switch_word);         //send one byte of data, ie switch_word
+    i2c_port.stop();                     //force a stop condition
+    wait(0.002);       
+    //receive a single byte of data, in correct I2C package
+    i2c_port.start();
+    i2c_port.write(addr|0x01);          //send address, with R/W bit set to Read
+    recd_val=i2c_port.read(addr);       //Read and save the received byte
+    i2c_port.stop();                    //force a stop condition
+
+    //set leds according to incoming word from slave
+    red_led=0;              //preset both to 0
+    green_led=0; 
+    recd_val=recd_val&0x03; //AND out unwanted bits
+    if (recd_val==1)
+      red_led=1;
+    if (recd_val==2)
+      green_led=1;
+    if (recd_val==3){
+      red_led=1;
+      green_led=1;
+    }
+  }
+}