Hi fellow makers 
Im using a mega2560 and a SIM900 on a selvmade board with several sensors, wifi, bluetooth, NRF24L01, a camera and SD card.
Im logging various weather data from inside and outside(sent over radio using NRF24L01) and by sms the user can "order" a picture and control the system. The system logs all weatherdata during one day to one file and i want to upload to the server once a day. Pictures uploaded when user sent sms and "order" one.
I got most of it working and my question is regarding uploading to FTP server.
I got the upload to the FTP server working, but im using a hardcoded filename at the moment in the AT command sent from the AVR and i want to implement a filesystem so that i can upload a picture and/or logfile with a new name each time but im unsure if this is possible based on the way the sim900 at commands are set up.
Im using parts of the code i found here:
http://dostmuhammad.com/ftp-file-download-sim900/
This is how i send the AT command with the file name:
sendATcommand("AT+FTPPUTNAME="testing.txt"", "OK", 2000);
I want "testing.txt" to be replaced with a new filename each time but im unsure how to do this.
Any suggestions?
.