Diff: main.cpp

Revision:

0:b7581833f14a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Jan 04 17:34:17 2010 +0000
@@ -0,0 +1,90 @@
+#include "mbed.h"
+
+/***************************
+* John W. Leimgruber III
+* Test Application
+* 1. Read analog value from LM34 temperature sensor and convert to deg Fahrenheit
+* 2. Filter using 3-tap median sampling every 1/3 second
+* 3. Append to local flash filesystem log file every 512 seconds
+* 4. Externally, use a python program I wrote based on matplotlib to grab and parse updated log file then display graphical plot
+*****************************/
+
+DigitalOut myled(LED1); // sanity test light
+Serial pc(USBTX, USBRX); // beautiful debugging tx, rx to Linux and Minicom @ /dev/ttyACM0 9600 8N1
+AnalogIn temp(p15);    // analog temperature sensor, LM34, reads +5 to +300 degF @ 10mv per deg and takes 5-30v Vin...
+
+LocalFileSystem local("local"); // setup local filesystem on the ~2mb internal flash
+Timer timer; // timer to generate delays, as I'm newbish and don't know about wait
+
+int main() 
+{
+    printf("Starting to read and log temperature data to local flash disk.\r\n"); 
+    char *tempData, filter[3];
+    unsigned int dataCount, filterCount;
+    FILE *fp = 0;
+    dataCount = 0;
+    filterCount = 0;
+    memset(filter, 3, 0x00);
+
+    // allocate 512 bytes of memory to store 512 seconds worth of temperature values at one per second stored in deg F [0,255]      
+    tempData=(char *) malloc(512);
+    if (!tempData)
+    {
+      fprintf(stderr, "Not enough memory to allocate 512 bytes for temperature data\n");
+      exit(1);
+    }
+
+    timer.reset();
+    timer.start();
+    while(1)
+    {    
+      //grab a temp reading ever second and convert to 0-255 in deg F
+      if(timer.read() > 0.333)
+      { // implement 3 tap median filter and oversample by 3x
+        filter[0] = filter[1];
+        filter[1] = filter[2];
+        filter[2] = (char) (temp.read() * 330.0 - 5.0);
+        filterCount++;
+
+        if(filterCount >= 3)
+        {
+          filterCount = 0;
+          if(filter[0] >= filter[1] && filter[0] <= filter[2] ||
+             filter[0] <= filter[1] && filter[0] >= filter[2])
+          {
+            tempData[dataCount] = filter[0];
+          }
+          else if(filter[1] >= filter[0] && filter[1] <= filter[2] ||
+                  filter[1] <= filter[0] && filter[1] >= filter[2])
+          {
+            tempData[dataCount] = filter[1];
+          }
+          else
+          {
+            tempData[dataCount] = filter[2];
+          }
+          // in case you want to grab some 'real-time' temp data and debugging...                 
+          printf("Temperature [%d] = %d deg F\r\n",dataCount, tempData[dataCount]);
+          dataCount++;
+        }
+        timer.reset();
+      }
+
+      // now that we've grabbed a full page of data, dump it do disk then start over...
+      if(dataCount >= 512)
+      {
+        myled = 1;
+        fp = fopen("/local/templog.dat", "ab");
+        if(!fp)
+        {
+          printf("File /local/templog.dat could not be opened for append binary writing!\r\n");
+          exit(1);
+        }
+        printf("Writing %d bytes to internal flash!\r\n", dataCount); // should always be 512 bytes? (maybe should keep writing until 512 hit... meh)
+        printf("Actually wrote %d bytes...\r\n", fwrite(tempData,1,dataCount,fp)); //memory array, sizeof(char), 512 bytes, file pointer
+        fclose(fp);
+        dataCount = 0;
+        myled = 0;
+      }
+    }
+}