I'm still learning about the RAM side of these micros, so just wanted to check what my limitations are.
I have my Arduino connected to the Relay Shield prototype I made, which features a SPI Port Expander and 4 Relays. The Relays are driven from the Port Expander so the only IO going to the Arduino is the SPI comms. I also have a SHT15 Temp/Humidity sensor attached to the Arduino.
Basically I just have a little program reading the temperature in every 10 seconds and then checking it against a set point, and then switching the relay accordingly.
What I want to do however is save the FLOAT temperature value into an array, so I can basically log the temperature over time. I only want to save the data once every 10 minutes, and I am just wondering what the best method of doing this is and how long I would be able to log for.
I am assuming that this has to be stored into RAM, so at a guess I don't have very much logging potential. I only need a few hours worth, and I plan to have a rolling array so the last few hours is stored and the oldest basically falls off the end.
I dont know how much RAM I would be using currently, and therefore dont know how much RAM I would have left.
I have seen people talk about PROGMEM, but I dont know if that is relevant for what I am trying to do or not. Or should I be using the EEPROM? Is this used for anything else in normal operation, or is it only used if you explicitly tell it to use the EEPROM?
Is someone able to assist and point me in the right direction please.
I am fine for defining the array etc, but just dont know if I have an option for storing it somewhere else (progmem maybe?), or how much logging potential I may have. Its just for a test, not for long term use. I would use a SD card or something for the final product, but just want to know what I can do in the mean time.