dsPIC33f internal Flash as EEPROM

STSCBE · Aug 19, 2017

Dear all,
For my application IÂ’m using 16-bit - dsPIC33FJ64GS606 microcontroller. The controller haven't EEPROM option. I found an option to use Program memory as for EEPROM from Microchip website

https://www.microchip.com/SWLibraryWeb/product.aspx?product=Data%20EEPROM%20Emulation%20for%20PIC

Actually i Got Project file but it cannot compile.

I dont know How to use that library for my application.
Help me out, or Is there any other option to use Flash memory as for EEPROM?

Thanks..

FvM · Aug 19, 2017

You didn't tell what's the exact problem is. The dee_emulation library is ready to use with xc16, other compilers need some adaption. I've used it e.g. with CCS C.

STSCBE · Aug 19, 2017

FvM said:
You didn't tell what's the exact problem is. The dee_emulation library is ready to use with xc16, other compilers need some adaption. I've used it e.g. with CCS C.

Actually im using xc16 compiler, but how to add this lib to my application?

Thanks

FvM · Aug 19, 2017

If I remember right, it's well described in the accompanying doc.

Basically, add the *.c and *.h files to your project, configure the occupied memory range appropriately, call DataEEInit() at start and read/write functions in your code.

Aussie Susan · Aug 20, 2017

Be careful about how you use the FLASH as an EEPROM.
The FLASH as a minimum of 10,000 erase/write cycles. I have no idea of what you intend to store in the emulated EEPROM and how often the values update but remember that you erase either a block or a row at a time (although you can write a single work as well as rows and blocks). While the EEPROM emulation can hide a lot of that from you, you can still reach the minimum number of erase cycles for a cell quite easily if you are not careful.
Also remember that the processor will stall during erase/write operation completes. This can impact other aspects of your application.
In general I've found that an external EEPROM overcomes all of these and is often a better design option.
Susan

betwixt · Aug 20, 2017

I second what Susan explains.

I came across an application (not mine I hasten to add!) logging data every second and storing it in FLASH. The idea obviously seemed good at the time but the endurance of the storage was only a few days before the IC had to be removed, erased and reprogrammed. In my applications logging to EEPROM (25LC1024) every second I've got devices still working perfectly well after 10 years.

Brian.

STSCBE · Aug 21, 2017

FvM said:
If I remember right, it's well described in the accompanying doc.

Basically, add the *.c and *.h files to your project, configure the occupied memory range appropriately, call DataEEInit() at start and read/write functions in your code.

Thnx, i Got :thumbsup:

- - - Updated - - -

Aussie Susan said:
Be careful about how you use the FLASH as an EEPROM.
The FLASH as a minimum of 10,000 erase/write cycles. I have no idea of what you intend to store in the emulated EEPROM and how often the values update but remember that you erase either a block or a row at a time (although you can write a single work as well as rows and blocks). While the EEPROM emulation can hide a lot of that from you, you can still reach the minimum number of erase cycles for a cell quite easily if you are not careful.
Also remember that the processor will stall during erase/write operation completes. This can impact other aspects of your application.
In general I've found that an external EEPROM overcomes all of these and is often a better design option.
Susan

but my application, I just read internal flash(2bytes), when my system power ON....After main loop i Wont...

STSCBE · Aug 21, 2017

And also, How to find user EEWrite Functions's data memory allocation in internal program memory?

FvM · Aug 21, 2017

And also, How to find user EEWrite Functions's data memory allocation in internal program memory?

Not clear what you're exactly asking for. All ram and rom allocations are shown in link map.

Be careful about how you use the FLASH as an EEPROM.

That's right of course. Eeprom emulation is primarily suited for parameters that are modified by user interaction, not for automatically generated data. The dee_emulation library provides a kind of flash file system which minimizes the number of erase cycles, a single parameter might be updated more than 10000 times. You can reduce the flash wear by assigning more flash sectors to the emulation.

Aussie Susan · Aug 22, 2017

From what you say in Reply #7, if you only want to read a value on power-up and never write to the emulated-EEPROM, then you don't need an EEPROM at all.
Simply declare the value as 'const' and the compiler will place it in the FLASH memory for you and generate all of the required code when you read the variable in your code.
Susan

STSCBE · Aug 23, 2017

Aussie Susan said:
From what you say in Reply #7, if you only want to read a value on power-up and never write to the emulated-EEPROM, then you don't need an EEPROM at all.
Simply declare the value as 'const' and the compiler will place it in the FLASH memory for you and generate all of the required code when you read the variable in your code.
Susan

okay, but
in between, if i need to update that declared value, what i do?

Easyrider83 · Aug 23, 2017

I did flash usage by additional task. If data have to be readed, it taken directly from flash array. If we need to write data, we read full page to RAM, than modify necessary value, than erase flash and write new data.
Normally, I keep all values in RAM and writing to flash by additional command to save endurance.

FvM · Aug 23, 2017

if i need to update that declared value, what i do?

Use DEEEmulation lib, or for very infrequent update, the simplified method suggested Easyrider83

STSCBE · Sep 5, 2017

Hi,
I'm trying to test the DEEEmulation library's read and write function and i found that some issue, they are,
1. After programming at the first time, Need to Writes twice time in the same location that is,

Code:

DataEEWrite(01,05);        // data, location
DataEEWrite(02,06);        // data, location
DataEEWrite(01,05);        // data, location
DataEEWrite(02,06);        // data, location

if i give single time it reads gives different values instead of what i Written :sad::sad:

2. And before 10 to 12 times the DataEEWrite and DataEERead function is works very good. but after that, reads only last written value. even writing new values.
and find the Terminal Test Image

:roll: :sad: ?????????????

FvM · Sep 5, 2017

Guess you are using DEEEmulation somehow incorrect, e.g. not initializing it properly.

It's just impossible to debug your work from a distance.

I suggest usual debugging methods, e.g. tracing code execution in MPLAB, watching what each write action does to the flash array. If you feel this is all over your head, consider the previously suggested external EEPROM solution.

STSCBE · Sep 5, 2017

FvM said:
Guess you are using DEEEmulation somehow incorrect, e.g. not initializing it properly.

It's just impossible to debug your work from a distance.

I suggest usual debugging methods, e.g. tracing code execution in MPLAB, watching what each write action does to the flash array. If you feel this is all over your head, consider the previously suggested external EEPROM solution.

Hmm, but as per procedure, i followed the initialization of DEEInit(); ... Can u see the image? there might clearfull

dsPIC33f internal Flash as EEPROM

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