I am new to Arduino.
I am using Ph sensor and want to save my ph sensor reading in EEPROM. whenever i am reading value in EEPROM, its only printing integer value.
can somebody help me in this regards??
here is my code:
And yet, we should know why your codes did not work:
1. The syntax of EEPROM.write() command is: EEPROM.write(address, byteData);
That means the allowable data range is: 0 to 255 (1-byte = 0x00 to 0xFF) -- only integer value and no fractional part.
2. When there is a floating point number (having integer and fractional part) like float x = 13.67, then four consecutive memory locations are needed to store the value of x. The said four memory locations will hole 32-bit (4x8) data which are genertaed according to binary332/IEEE-754 standard (Fig-1).
3. Using write() method, we can store the value x of Step-2 by executing the following codes:
float x = 13.67;
ptr = (byte*)&x; //ptr holds beginning address of 4-byte memory space containing value of x
for (int i = 0, address = 0; i < 4; i++, address++, ptr++)
4. All the codes of Step-3 can be replaced by the following two lines of codes:
And yet, the @ashish_senger has made the mistake which proves that it is a difficult task for him. Therefore, the theroy of the EEPROM.write(unsigned int arg1, byte arg2) method should be made clearer to him by way of examples.
What I meant was that the explanation was quite simple. Personally I think that you have made the explanation more complicated by bringing up the subject of how a float is represented in memory and how the value of the float is calculated from that representation. None of that matters in this case
Remember you can only write 100,000 times at a given address in EEPROM
A float value - with the variability or analogRead() - is likely to change slightly often.
You have a 1 second delay between two reads, if the value keeps changing (even slightly) and is above the threshold at every read then you’ll destroy ERPROM address 0 in a bit more than a day (roughly in 27h and 47 min)
You might want to only keep 1 significant digit (or none - do you know the orecision of your device?) and adopt a strategy where you write to EEPROM only when you get significant changes or (with a bit of extra hardware) when the arduino looses power only
Thank you so much for your explanation. It is just a basic code. i am still working and trying to reduce the sample size (Applying for loop or using average method ). so i can merge 10-15 values in a single output.
You could store the sample to EEPROM, and store the next sample 4 bytes further. At the end of the EEPROM, loop around and keep track of where the new data should be stored. Then you would have the 128 latest samples.
It needs good code and a mistake is easily made.
Using the average of a few samples is always good.