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Groups > comp.arch.embedded > #24805
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: What is your strategy to save non volatile data? |
| Date | 2016-08-11 16:12 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <noi142$ih$1@dont-email.me> (permalink) |
| References | <nohs7p$ff3$1@dont-email.me> |
On 11/08/16 14:48, pozz wrote: > Many times I work on embedded projects where it is required to save some > data in a non volatile way. Usualy I use external (to the main > microcontroller) serial/parallel EEPROM or internal Flash memory (with a > software layer for EEPROM emulation). > > However my goal isn't to discuss the hw alternatives, but the data > format and strategy. > > I know there are many serialization data format (XML, JSON, Protocol > Buffer, SQLite), but I don't think they are valid solutions for > medium/low end microcontrollers. They are complex to implement and they > aren't really necessary. > Data are written and read from the same platform, so the endianess and > byte order are not a problem. > > IMHO directly saving a C structure to the non-volatile memory is the > best method. When you will load bytes from the non volatile memory, you > will have magically your C structure in RAM filled with the saved values. > > Is it the same strategy that you use? As Don says, there is no single best method. The answer to almost every question in embedded development is "it depends". But for the common case of storing a small set of parameters, I usually work with a struct definition. Along with the parameters in question, I include a "magic number" for identification, a "parameter structure version number" (very useful for upgrading the parameter set if a later version of the firmware uses more parameters), an update serial number, a CRC check field, and some space reserved for future additional parameters. Typically I have a statically allocated struct in ram, and two copies in eeprom or flash. On startup, I check both non-volatile copies to see which is the latest version (highest serial number) that has a valid CRC, and copy that into RAM. If the parameter structure version number does not match the current firmware requirements, I upgrade the parameters. When I need to save the parameters, I use the oldest of the two NV sets. First, I erase it (for eeprom, that's just clearing the magic number). Then I copy in most of the data and CRC, leaving the magic number for last. I have had occasion to use a log structured parameter "file system" in flash, but usually such complications are unnecessary. And certainly SQLite, or JSON, etc., are normally overkill.
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What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-11 14:48 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 06:27 -0700
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-11 16:12 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 07:53 -0700
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 08:27 -0700
Re: What is your strategy to save non volatile data? bitrex <bitrex@de.lete.earthlink.net> - 2016-08-11 12:11 -0400
Re: What is your strategy to save non volatile data? bitrex <bitrex@de.lete.earthlink.net> - 2016-08-11 12:12 -0400
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 11:35 -0700
Re: What is your strategy to save non volatile data? bitrex <bitrex@de.lete.earthlink.net> - 2016-08-11 20:59 -0400
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 11:33 -0700
Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 00:21 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 15:40 -0700
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-11 23:07 +0200
Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 00:17 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 15:30 -0700
Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 09:02 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-12 09:29 -0700
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 11:54 +0200
Re: What is your strategy to save non volatile data? John Devereux <john@devereux.me.uk> - 2016-08-12 13:14 +0100
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 15:22 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-12 09:40 -0700
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 22:40 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-13 09:44 -0700
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-14 23:01 +0200
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 09:52 +0200
Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 16:30 +0200
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 17:09 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 15:36 -0700
Re: What is your strategy to save non volatile data? Paul <paul@pcserviceselectronics.co.uk> - 2016-08-12 03:21 +0100
Re: What is your strategy to save non volatile data? bitrex <bitrex@de.lete.earthlink.net> - 2016-08-11 12:19 -0400
Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-11 23:49 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-11 15:37 -0700
Re: What is your strategy to save non volatile data? John Devereux <john@devereux.me.uk> - 2016-08-11 20:50 +0100
Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-12 00:16 +0200
Re: What is your strategy to save non volatile data? Paul <paul@pcserviceselectronics.co.uk> - 2016-08-12 03:34 +0100
Re: What is your strategy to save non volatile data? David Brown <david.brown@hesbynett.no> - 2016-08-12 11:59 +0200
Re: What is your strategy to save non volatile data? Paul Rubin <no.email@nospam.invalid> - 2016-08-11 11:29 -0700
Re: What is your strategy to save non volatile data? Les Cargill <lcargill99@comcast.com> - 2016-08-12 12:15 -0500
Re: What is your strategy to save non volatile data? Joe Chisolm <jchisolm6@earthlink.net> - 2016-08-12 12:10 -0500
Re: What is your strategy to save non volatile data? Paul <paul@pcserviceselectronics.co.uk> - 2016-08-12 22:00 +0100
Re: What is your strategy to save non volatile data? Tim Wescott <tim@seemywebsite.com> - 2016-08-13 12:06 -0500
Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-13 23:42 +0200
Re: What is your strategy to save non volatile data? Don Y <blockedofcourse@foo.invalid> - 2016-08-13 15:55 -0700
Re: What is your strategy to save non volatile data? Paul <paul@pcserviceselectronics.co.uk> - 2016-08-14 00:08 +0100
Re: What is your strategy to save non volatile data? Tim Wescott <tim@seemywebsite.com> - 2016-08-13 19:06 -0500
Re: What is your strategy to save non volatile data? pozz <pozzugno@gmail.com> - 2016-08-22 09:46 +0200
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