Memory Question for datalog apps
Archiver
Posts: 46,084
Dataloggers are typically using static ram, which may also be battery
backed up.
The spec you mention is probably applied to EEPROM which has a
limitation of the number of writes to any single memory cell.
If the previous 128 K of memory will take care of your requirements
for 20 minutes, then as long as you use all of the memory for argument
sake, then 20 minutes x 100,000 writes will last 2 million minutes.
divide by 525,600 (minutes in a typical year) your EEPROM memory will
last approximately 4 years with continuous use.
Which I doubt you will do.
IF you design a system with the proper hardware, you could store all
data in static ram and the shutdown procedure would write all static
ram data to EEPROM prior to removal of power. The shutdown button
would initiate the data recovery and storage, prior to having the
software/micro powering down. Thus the EEPROM would last longer than
we would in this case.
Just and idea.
Ron
Original Message
From: <egroups@d...>
To: <basicstamps@egroups.com>
Sent: Friday, July 28, 2000 2:54 AM
Subject: [noparse][[/noparse]basicstamps] Memory Question for datalog apps
> Hey guys,
>
> I've been using the BSII to do a few projects, and the latest one
> requires logging 8 numbers at 10Hz for 20 minutes. As I haven't used
> memory before to store data, can someone please clarify the
> following...
>
> 1. If the number is 0 to 65000, then it's a word, and 1 word = 2
> bytes. If I log at 10 Hz, then in 1 sec I am storing 10 words, or 20
> bytes. For one minute this jumps to 20b x 60s = 1200 bytes or 1.2Kb.
> For 20 min this is 20m x 1200b = 24000 or 24 Kb. Is this correct.
>
> If the above is correct an I do this for 8 inputs, the memory usage
> jumps to 24000 x 8 = 192 Kb. If I do this for 20 minutes then I am
> completing 96000 writes to memory ( 8 writes x 10 hz for 20 min ).
>
> If I write to 128K mem, it is only good for 100,000 writes, so
> basically, I can only log for 20 min before having to replace the
> memory chip??? Is this correct.
>
> If this is so, how to professional dataloggers work, ie they store
> data at 100hz for multiple channels at up to 1 hour, but this can be
> done till the cows come home. What mem are they using that doesn't
> need to be replaced, or am I missing something and making an idiot
of
> myself???
>
> Sorry for the long speil, but please help..
>
> Thanks in advance
>
>
>
>
>
>
backed up.
The spec you mention is probably applied to EEPROM which has a
limitation of the number of writes to any single memory cell.
If the previous 128 K of memory will take care of your requirements
for 20 minutes, then as long as you use all of the memory for argument
sake, then 20 minutes x 100,000 writes will last 2 million minutes.
divide by 525,600 (minutes in a typical year) your EEPROM memory will
last approximately 4 years with continuous use.
Which I doubt you will do.
IF you design a system with the proper hardware, you could store all
data in static ram and the shutdown procedure would write all static
ram data to EEPROM prior to removal of power. The shutdown button
would initiate the data recovery and storage, prior to having the
software/micro powering down. Thus the EEPROM would last longer than
we would in this case.
Just and idea.
Ron
Original Message
From: <egroups@d...>
To: <basicstamps@egroups.com>
Sent: Friday, July 28, 2000 2:54 AM
Subject: [noparse][[/noparse]basicstamps] Memory Question for datalog apps
> Hey guys,
>
> I've been using the BSII to do a few projects, and the latest one
> requires logging 8 numbers at 10Hz for 20 minutes. As I haven't used
> memory before to store data, can someone please clarify the
> following...
>
> 1. If the number is 0 to 65000, then it's a word, and 1 word = 2
> bytes. If I log at 10 Hz, then in 1 sec I am storing 10 words, or 20
> bytes. For one minute this jumps to 20b x 60s = 1200 bytes or 1.2Kb.
> For 20 min this is 20m x 1200b = 24000 or 24 Kb. Is this correct.
>
> If the above is correct an I do this for 8 inputs, the memory usage
> jumps to 24000 x 8 = 192 Kb. If I do this for 20 minutes then I am
> completing 96000 writes to memory ( 8 writes x 10 hz for 20 min ).
>
> If I write to 128K mem, it is only good for 100,000 writes, so
> basically, I can only log for 20 min before having to replace the
> memory chip??? Is this correct.
>
> If this is so, how to professional dataloggers work, ie they store
> data at 100hz for multiple channels at up to 1 hour, but this can be
> done till the cows come home. What mem are they using that doesn't
> need to be replaced, or am I missing something and making an idiot
of
> myself???
>
> Sorry for the long speil, but please help..
>
> Thanks in advance
>
>
>
>
>
>
Comments
I've been using the BSII to do a few projects, and the latest one
requires logging 8 numbers at 10Hz for 20 minutes. As I haven't used
memory before to store data, can someone please clarify the
following...
1. If the number is 0 to 65000, then it's a word, and 1 word = 2
bytes. If I log at 10 Hz, then in 1 sec I am storing 10 words, or 20
bytes. For one minute this jumps to 20b x 60s = 1200 bytes or 1.2Kb.
For 20 min this is 20m x 1200b = 24000 or 24 Kb. Is this correct.
If the above is correct an I do this for 8 inputs, the memory usage
jumps to 24000 x 8 = 192 Kb. If I do this for 20 minutes then I am
completing 96000 writes to memory ( 8 writes x 10 hz for 20 min ).
If I write to 128K mem, it is only good for 100,000 writes, so
basically, I can only log for 20 min before having to replace the
memory chip??? Is this correct.
If this is so, how to professional dataloggers work, ie they store
data at 100hz for multiple channels at up to 1 hour, but this can be
done till the cows come home. What mem are they using that doesn't
need to be replaced, or am I missing something and making an idiot of
myself???
Sorry for the long speil, but please help..
Thanks in advance