Dirty little program to grab analog sensor data, apply a 3-tap median filter, and log it to a local flash file.
Revision 0:b7581833f14a, committed 2010-01-04
- Comitter:
- leimgrub
- Date:
- Mon Jan 04 17:34:17 2010 +0000
- Commit message:
Changed in this revision
main.cpp | Show annotated file Show diff for this revision Revisions of this file |
mbed.bld | Show annotated file Show diff for this revision Revisions of this file |
--- /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; + } + } +}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Mon Jan 04 17:34:17 2010 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/49a220cc26e0