Oleg Evsegneev / FRAMLog

Log system based on external FRAM storage. Allow to collect float values in FRAM, and then store whole collection into file on flash.

Sample code

#include "mbed.h"
#include "FRAMLog.h"

SPI spi(p5,p6,p7);
FRAMLog flog(spi, p8, 4, 2048);
Serial pc(USBTX, USBRX);

int main() {
    for( int i=0; i<2048; i++){
        flog.log(i/4096.0);
        flog.log(i/(4096.0+1));
        flog.log(i/(4096.0+2));
        flog.log(i/(4096.0+3));
    }
    flog.save();
}

Diff: FRAMLog.cpp

Revision:
1:4e5cda0920d3
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FRAMLog.cpp	Sun Oct 21 20:29:57 2012 +0000
@@ -0,0 +1,66 @@
+/* Log system for FRAM+FLASH
+* Copyright (c) 2012 Oleg Evsegneev
+* Released under the MIT License: http://mbed.org/license/mit
+*
+* Datasheet http://www.ramtron.com/files/datasheets/FM25V02_ds.pdf
+*/
+ 
+#include "mbed.h"
+#include "FRAMLog.h"
+
+FRAMLog::FRAMLog( SPI& spi, PinName ncs, short cols, short rows ): _fram(spi, ncs), _local("local") {
+    _cols = cols;
+    _rows = rows;
+    _addr = 0;
+    _row = 0;
+}
+
+float FRAMLog::fromArray( char *bytes ){
+    union {
+        float f;
+        unsigned char b[4];
+    } v;
+
+    for( char i=0; i<4; i++ )
+        v.b[i] = bytes[i];
+
+    return v.f;
+}
+
+void FRAMLog::toArray( float val, char *bytes ){
+    union {
+        float f;
+        unsigned char b[4];
+    } v;
+    v.f = val;
+
+    for( char i=0; i<4; i++ )
+        bytes[i] = v.b[i];
+}
+
+void FRAMLog::log( float val ) {
+    char bytes[4];
+    toArray( val, bytes );
+    _fram.write(_addr, bytes, 4);
+    _addr += 4;
+    if( ( _addr % (_cols*4)) == 0 )
+        _row++;
+}
+
+void FRAMLog::save() {
+    FILE *fp = fopen(LOG_FILE, "w");
+    char bytes[4];
+    unsigned short addr = 0;
+    
+    for( short i=0; i<_row; i++){
+        for( short k=0; k<_cols; k++){
+            _fram.read(addr, bytes, 4);
+            addr += 4;
+            fprintf( fp, "%.4f", fromArray(bytes));
+            if( k < _cols-1 )
+                fprintf( fp, "\t");
+        }
+        fprintf( fp, "\r\n");
+    }
+    fclose(fp);
+}