Diff: main.cpp

Revision:

67:18117455f5cb

Parent:

66:0a43d8aeeb76

--- a/main.cpp	Tue Jun 26 17:52:09 2018 +0000
+++ b/main.cpp	Thu Aug 23 14:02:08 2018 +0000
@@ -1,14 +1,82 @@
 #include "mbed.h"
 
-DigitalOut led1(LED1);
+#define MCP9808_ADDR     (0x30) // MCP9808 base address 0x18<<1
+#define MCP9808_REG_TEMP (0x05) // Temperature Register
+#define MCP9808_REG_CONF (0x01) // Configuration Register
+#define MCP9808_REG_CRIT (0x04) // Critical Temperature Register
+
+// Uncomment to use file save
+// LocalFileSystem local("local");               // Create the local filesystem under the name "local"
 
-// main() runs in its own thread in the OS
+Serial pc(USBTX, USBRX);
+I2C i2c(p9, p10);   // SDA, SCL on MCP9808
+// Note MCP9808 also needs VCC (3.3 V) and GND
+
+float TempValue;
+float data[20];
+char data_write[3], data_read[2];
+int ii, status;
 int main() {
-    while (true) {
-        led1 = !led1;
-        wait(0.02);
-        led1 = !led1;
-        wait(0.02);
+    // Wake up
+    data_write[0] = MCP9808_REG_CONF; // Register address
+    data_write[1] = 0x00;  // Data MSB, b11-15 not used, b9-10 =>T_HYS=0, b8 => continuous conversions
+    data_write[2] = 0x04;  // Data LSB,  Alert Off, Alert Disabled, Alert T>T_Crit, Alert active low, Alert interrupt
+    status = i2c.write(MCP9808_ADDR, data_write, 3, 0); // address,data,length,repeat
+    // address is chip addess
+    // First byte of data has register address 
+    // repeat true for multiple write when the chip autoincrements the address
+    // MCP9808 does not do this, so we leave it at 0
+      
+    while(1){
+        int i=0;
+        // this loops takes 20 data points and then
+        // appends those data points to a file
+        // the file write will be mostly closed, so the mbed
+        // file system will be available to a host computer
+        // See warning below
+        while(i<20){
+        // Read temperature  
+            data_write[0] = MCP9808_REG_TEMP;
+            i2c.write(MCP9808_ADDR, data_write, 1, 1); // no stop
+            i2c.read(MCP9808_ADDR, data_read, 2, 0);
+            status = data_read[0] >> 5;  // Shift flags to b0-b2
+            // 1 in flag means: T>T_crit(b2), T>T_Upper(b1), T<T_Lower(b0)
+           // pc.printf("the status is %n",status);
+            data_read[0] = data_read[0] & 0x1F;  // clear flag bits for temperature
+            
+            data[i] = (data_read[0] * 16) + (data_read[1] / 16.0); // combine two bytes
+            // Display the flags, if you wish
+            // pc.printf("Flags are %i \n\r",status);
+            // This displays to the user
+            pc.printf("%i Temperature is %3.1f\n\r",i,data[i]);
+            i=i+1;
+            wait(1);
+        }
+/*        
+If the microcontroller program opens a file on the local drive, it will be marked as “removed” on the Host computer.
+This means the PC will often display a message such as "insert a disk into drive" if you try to access it at this time;
+this is normal, and stops both the mbed and the PC trying to access the disk at the same time.
+
+The USB drive will only re-appear when all file handles are closed in your program, or the microcontroller program exits.
+If a running program on the mbed does not exit or does not release it's open file handles, you will no longer be able to see the USB drive
+when you plug the mbed into your PC.
+
+To allow you to see the drive again (and load a new program), use the following procedure:
+
+        Unplug the microcontroller
+        Hold the reset button down
+        While still holding the button, plug in the microcontroller. The mbed USB drive should appear.
+        Keep holding the button until the new program is saved onto the USB drive.
+
+*/
+ // This section does the file ave
+ /*
+        FILE *fp = fopen("/local/out.txt", "a");  // Open "out.txt" on the local file system for writing
+        for( ii = 0; ii < 20; ii++ ){
+            fprintf(fp, "Temperature is %3.1f\r\n",data[ii]);
+        }
+        fclose(fp);
+*/
+
     }
 }
-