Diff: main.cpp

Revision:

0:b4dab7bb911f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Aug 29 15:01:37 2013 +0000
@@ -0,0 +1,45 @@
+/*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(LED1); //red led
+DigitalOut green_led(LED2); //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 recognizable 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 word received 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;
+        }
+    }
+}