Diff: main.cpp

Revision:

0:039f25b3de3e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sat Mar 05 18:34:25 2016 +0000
@@ -0,0 +1,114 @@
+#include "mbed.h"
+
+
+DigitalOut myled(LED1); //displays I2C wait
+
+I2C i2c(p28,p27);   //sda,scl
+Serial pc(USBTX,USBRX);  //serial usb config
+
+bool ch,ch2,ch3;
+float temp; //temperature in degrees C
+char p1,p2;
+ 
+ /* Change MLX90614 address
+ 
+ 1. clear old address
+ 2. set new address
+ 3. check if the change happenned
+ 4. power cycle sensor (reconnect power)
+ 
+ */
+ 
+int main() {
+    while (1) {
+
+//----clear old address------------------
+        
+        // make sure i2c is inactive
+        i2c.stop();            
+        wait(0.1);
+        //send start bit
+        i2c.start();
+        // address the sensor using universal address 0x00 not its default 0x5A
+        ch = i2c.write(0x00); // last bit 0 indicates write
+        // prints if sensor acknowledges
+        if (!ch){ pc.printf("no ack\n"); }
+        else pc.printf("ack 0x00\n");
+        // write command
+        // EEPROM address. Datasheet says 0x0E BUT!!! accessing EEPROM requires ading 0x20. Hence, 0x2E
+        ch2 = i2c.write(0x2E);
+        // prints if sensor acknowledges
+        if (!ch2) pc.printf("no ack address location\n");
+            pc.printf("ack 0x0E\n");
+        // delete old address
+        // LSB
+        i2c.write(0x00);
+        // MSB
+        i2c.write(0x00);
+        // use CRC-8 calculator to obtain PEC bit http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
+        // I send 2E0000 --> PEC 0x6F
+        ch3 = i2c.write(0x6F);
+        // prints if sensor acknowledges
+        if(!ch3) pc.printf("no PEC\n");
+            else pc.printf("PEC success\n");
+        // release the bus
+        i2c.stop();
+        wait(1);
+    
+//-----set new address----------------
+    
+        // send start bit
+        i2c.start();
+        // send universal device address 0x00
+        i2c.write(0x00);
+        // prints if sensor acknowledges
+        if (!ch) pc.printf("no ack\n");
+        else pc.printf("ack\n");
+        // send EEPROM location for slave address
+        ch2 = i2c.write(0x2E);
+        // prints if sensor acknowledges
+        if (!ch2) pc.printf("no ack slave address location\n");
+        else pc.printf("ack 2\n");
+        //write new address anything between 0x0000 and 0x007F (default 0x5A, PEC 0xE1)
+        // LSB
+        i2c.write(0x04);
+        // MSB
+        i2c.write(0x00);
+        // send PEC calculated from CRC-8
+        // I send 2E0400 -> PEC 0x3B 
+        i2c.write(0x3B);
+        // release the bus
+        i2c.stop();
+        wait(1);
+        
+//----read address to make sure it worked------------
+
+        // send start bit
+        i2c.start();
+        // send universal address
+        ch = i2c.write(0x00);
+        // prints if sensor acknowledges
+        if (!ch) pc.printf("no ack\n");
+        else pc.printf("ack\n");
+        // send EEPROM slave location address
+        ch2 = i2c.write(0x2E);
+        // send repeated start
+        i2c.start();
+        // send universal address 0x00 (seven bit) and use 1 as the eight bit -> 0x01
+        i2c.write(0x01); // last bit 1 indicates read request
+        // read LSB
+        p1 = i2c.read(1);
+        // read MSB
+        p2 = i2c.read(1);
+        // read PEC
+        i2c.read(0);
+        // release the bus
+        i2c.stop();
+        wait(0.1);
+        // print hex
+        pc.printf("0x%x%x\nMSB 0x%x, LSB 0x%x\n", p2, p1, p2, p1);
+        wait(10);
+        
+//-----now turn of the sensor for the change to take effect----do not access it without turning it off first!!!!-------     
+    }
+}