OK the OP wanted suggestions on memory chips for storing logged data.

I am also on one such project. I have a small idea on which I would like to get some inputs from members. In a typical data logging setup, there are some channels which are relatively slow as compared to rest - for instance a temperature channel where the values almost remian constant for a large number of samples.

In such an event instead of wasting precious memory to store repeated values, I was wondering if I could code as follows.

1. Sample the slow channel.
2. Compare with 5 previous values.
3. If all are same ( within a specified band) then save the value + a count initialised to 6.
4. On subsequent samples, just keep incrementing the counter as long as the value is stable.
5. On the first deviation ( outside the specified band) stop the count and save the Data_Val & Count to the data base. Reset the Count.

Though I have not tried the above, I have a feeling that it can save quite a bit of space.


Any comments or other ideas to save storage space ?

Thanks

Raghu