using millis() fro printing

Projects Programming
1

I am trying to write a program that writes data to a file, including a timestamp (mytime). I am getting the following error when trying to append the timestamp to the file:

"error: converting to 'String' from initializer list would use explicit constructor 'String::String(long int, unsigned char)'

appendFile("DATA.TXT", mytime);"

mytime is defined by the global variable:
"unsigned long mytime=0;"

and the timestamp is updated in a loop by the following instruction:
"mytime=millis();"

2

You need to post the complete program. If it is a long program maybe you can create a short version that illustrates the problem.

...R

3

unsigned long mytime=0;
loop{
mytime = millis();
appendFile("DATA.TXT", mytime);
}
void appendFile(String fileName, String data){
resetALL(); //Reset the module
set_USB_Mode(0x06); //Set to USB Mode
diskConnectionStatus(); //Check that communication with the USB device is possible
USBdiskMount(); //Prepare the USB for reading/writing - you need to mount the USB disk for proper read/write operations.
setFileName(fileName); //Set File name
fileOpen(); //Open the file
filePointer(false); //filePointer(false) is to set the pointer at the end of the file. filePointer(true) will set the pointer to the beginning.
fileWrite(data); //Write data to the end of the file
fileClose(0x01); //Close the file using 0x01 - which means to update the size of the file on close.
}
*note: I did not write the appendFile function. this had been provided to me for this project

4

The code is still incomplete, no includes (which libraries?) and no setup and you did not use code tags to format it. The 15% of the code you wrote your self will become a problem, the loop function will be executed very fast over and over, and the code will eventually add contents to the file so quick that it will generate a huge amount of data. "mytime" is a numeric value which starts from zero when the arduino is reset and then it will increment to 2^32 and start over again. If you want to write that number to the file, you will need to convert it to a cstring (do not use the "String" class, it will become a problem for you!).

char buffer[15];
ultoa(mytime, buffer, 10); //Unsigned Long TO Ascii
appendFile("FILE.TXT", buffer);
5 
void appendFile(String fileName, String data){

The function requires that the data be of the String data type. You can change the unsigned long to a String with

String data = String(mytime);

Then call the function with:

appendFile("DATA.TXT", data);"

FYI it is a bad idea to use the String data type with micro controllers with limited memory. Here is why, along with ways to use c-strings in their place.

Please read the "how to use this forum-please read" sticky to see how to properly post code.

6

unfortunately, I am aware of a lot of the poor practice being used in this program. I did not make the decisions, but the program was mostly already written for me, and I'm just trying to reformat the output that it produces.