Diff: main.cpp

Revision:

0:1e8f259cef5b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun May 03 01:18:30 2015 +0000
@@ -0,0 +1,71 @@
+#include "mbed.h"
+ 
+#define LM75_REG_TEMP (0x00) // Temperature Register
+#define LM75_REG_CONF (0x01) // Configuration Register
+#define LM75_ADDR     (0x90) // LM75 address
+ 
+I2C i2c(I2C_SDA, I2C_SCL);
+ 
+DigitalOut myled(LED1);
+ 
+Serial pc(SERIAL_TX, SERIAL_RX);
+ 
+volatile char TempCelsiusDisplay[] = "+abc.d C";
+ 
+int main()
+{
+ 
+    char data_write[2];
+    char data_read[2];
+ 
+    /* Configure the Temperature sensor device STLM75:
+    - Thermostat mode Interrupt
+    - Fault tolerance: 0
+    */
+    data_write[0] = LM75_REG_CONF;
+    data_write[1] = 0x02;
+    int status = i2c.write(LM75_ADDR, data_write, 2, 0);
+    if (status != 0) { // Error
+        while (1) {
+            myled = !myled;
+            wait(0.2);
+        }
+    }
+ 
+    while (1) {
+        // Read temperature register
+        data_write[0] = LM75_REG_TEMP;
+        i2c.write(LM75_ADDR, data_write, 1, 1); // no stop
+        i2c.read(LM75_ADDR, data_read, 2, 0);
+ 
+        // Calculate temperature value in Celcius
+        int tempval = (int)((int)data_read[0] << 8) | data_read[1];
+        tempval >>= 7;
+        if (tempval <= 256) {
+            TempCelsiusDisplay[0] = '+';
+        } else {
+            TempCelsiusDisplay[0] = '-';
+            tempval = 512 - tempval;
+        }
+ 
+        // Decimal part (0.5°C precision)
+        if (tempval & 0x01) {
+            TempCelsiusDisplay[5] = 0x05 + 0x30;
+        } else {
+            TempCelsiusDisplay[5] = 0x00 + 0x30;
+        }
+ 
+        // Integer part
+        tempval >>= 1;
+        TempCelsiusDisplay[1] = (tempval / 100) + 0x30;
+        TempCelsiusDisplay[2] = ((tempval % 100) / 10) + 0x30;
+        TempCelsiusDisplay[3] = ((tempval % 100) % 10) + 0x30;
+ 
+        // Display result
+        pc.printf("temp = %s\n", TempCelsiusDisplay);
+        myled = !myled;
+        wait(1.0);
+    }
+ 
+}
+