diff --git a/Makefile b/Makefile
index 7e1f898..f47f1fe 100644
--- a/Makefile
+++ b/Makefile
@@ -1,2 +1,6 @@
-default:
-	g++ -Wall -g -std=c++11 -o bin2csv main.cpp
+output: main.o
+	g++ -Wall -g -std=c++11 main.o -o bin2csv
+main.o:	main.cpp
+	g++ -Wall -g -std=c++11 -c main.cpp
+clean:
+	rm *.o bin2csv
diff --git a/README.md b/README.md
index 042b531..c890b28 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # bin2csv
 convert binary files from SdFat AnalogBinLogger to csv files on an pc (x64).
-
+https://github.com/greiman/SdFat/tree/master/examples/AnalogBinLogger
 compile with:
 
 cd bin2csv  
diff --git a/main.cpp b/main.cpp
index 61bd3ef..fa75d29 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,3 +1,22 @@
+/*///////////////////////////////////////////////////////
+
+bin2csv is to convert binary files produced by SdFats
+"AnalogBinLogger"
+
+https://github.com/greiman/SdFat/tree/master/examples/AnalogBinLogger
+
+compile:
+# cd bin2csv
+# make
+
+To run the conversion just supply
+bin2csv with an input binary file and an output csv file.
+(tested only on x64 linux). 
+I am a c++ beginner so errors are likely 
+
+////////////////////////////////////////////////////////*/
+
+
 #include <iostream>
 #include <fstream>
 #include <sstream>
@@ -154,6 +173,7 @@ int main ( int argc, char* argv[] )
           std::cerr << "Usage: \t" << argv[0] << " input.bin output.csv\n";
           break;
      case 2:
+		 iFileName = argv[1];
           std::cerr << "ERROR, no output file specified!\n";
           break;
      case 3: