Data Storage to SD Card with a few caveats

hello,

being new forums (but not arduino!) hope right area questions...

i want figure out way few things logged on sd card either uno or mega... not sure 1 yet, have see how many pins need.

but anyhow, goal this:

1- user inputs number matrix keypad (i.e. 1 or 11 or 12). whole numbers only, , positive numbers 1-99
2- arduino reads sensor, depending on button pressed (let's call button 1), , logs value in .csv (i.e. 1,7.4)
3- user repeats step one
4- here gets interesting: if user inputs 1, presses button 2, want arduino revise .csv entry 1 to, say, 1,7.4,8.2

i do not want multiple entries in .csv like:

1,7.5
1,8.2
1,9.0

is possible?

the application of project require 1 sensor reading (like temperature) of 10 samples (each assigned number 1-10). then, temp sensor switched out different sensor , same samples read, different variable. eventually, ideal .csv entry 1,x,y,z

so can this? can figure out basic sd entry tasks, , i'll integrate lcd , few led indicators. data logging comes first , foremost.

any suggestions on how approach this?

many thanks,

hi,

rather write record sd each time sensor read, collate values, write record once when next button pressed.  remove need revise .csv.  if you're talking maximum of 10 readings each time easy populating array of values , writing values out when next button pressed.

cheers ! geoff

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