write_configuration_memory() compilation error

[ftoffolon]

Hi,
I've have to write on user ID area a checksum code for bootloading reason. Normally in my previous PIC18 and PIC16 designs I use write_program_eeprom API and it works as expected. Now I'm approaching a project with PIC16F18325 and it doesn't works. I've seen documentation and I've found new APIs for accessing that area :
write_configuration_memory() and read_configuration_memory().
read_configuration_memory works as expected but with write_configuration_memory, compiler raise an error that I don't understand. Below the compiler's output with error and a simple example with the API.

ERROR ->
>>> Warning 240 "test_ccs.c" Line 19(35,36): Pointer types do not match
*** Error 102 "test_ccs.c" Line 19(35,36): Expect comma
1 Errors, 1 Warnings.
Build Failed.
<-

[Ttelmah]

Look at the data sheet.

Look at table 10-3.

What does the column 'write access' say about the configuration words?....

Because it cannot work, the compiler is 'hiccuping', and thinking you mean to use an offset, and so should have the third parameter....

[ftoffolon]

My device table says that I can also write on user id area (0x8000-0x8003).
I've also tried to put optional 1st parameter to zero, so no offset 'cause the user id area is on 1st address of configuration memory, but another error comes from compiler :

[RF_Developer]

The manual entry for write_configuration_memory() says:

[ftoffolon]

Sorry RF_Developer but on compiler (rel. 5.061) documentation of write_configuration_memory() says that, on Enhanced16, I can use it for User ID memory, and microcontroller datasheet says it's writable.

See CCS manual extract :

->

write_configuration_memory( )
Syntax:
write_configuration_memory ([offset], dataptr,count)

Parameters:
dataptr: pointer to one or more bytes
count: a 8 bit integer
offset is an optional parameter specifying the offset into configuration memory to start writing to, offset defaults to zero if not used.
Returns:
undefined
Function:
For PIC18 devices-Erases all fuses and writes count bytes from the dataptr to the configuration memory.
For Enhanced16 devices - erases and write User ID memory.

Availability:
All PIC18 Flash and Enhanced16 devices
<-


Regards

[temtronic]

I downloaded the datasheet for that PIC and all I can find is ...
Program Flash memory consists of 8192 14-bit words
as user memory, with additional words for user ID
information, Configuration Words, and interrupt
vectors. Program Flash memory provides storage
locations for:
• User program instructions
• User defined data
Program Flash memory data can be read and/or written
to through:
• CPU instruction fetch (read-only)
• FSR/INDF indirect access (read-only)


Please note (read-only) !!

So I'm assuming that you cannot 'actively' write to memory, unlike other PICs.

Others will know for sure but usually Microchip will 'promote' any feature like R/W mem. Now there may be a 'family' memeber of that PIC that does have the feature.

You have to remmeber just because the compiler has a function that works on some PICS you need to confirm by reading read datasheet which these days is 400-500 pages long !

Jay

[Ttelmah]

If you look at the table I referred to, the main memory is writeable, but the configuration area isn't. The ID should be, but I'm not sure how.

I'd have to sit down and write a routine to do it. Problem is that the standard write will try to erase a page, and the configuration memory is in the same page, and not writeable!......
Duh.

[Ttelmah]

I have to ask. Why not put the checksum in the EEPROM?.

This is much easier memory to use. Byte wide, and can be written and erased byte by byte. Even if you are using the EEPROM for other things, you could reserve (say) the last four bytes of this for a checksum.

Alternatively, the standard way, is just to have the last couple of words in the main memory, containing a value to make the whole of memory 'sum' to a particular constant.

CCS have omitted the write_configuration_memory function, since there are only 4*14bits that can actually be written using it. If you must go this way, then ask them to add it, or write your own.

[ftoffolon]

Hi,

to temtronic :

on PIC16F18325 datasheet (last release), after row FSR/INDF indirect access (read-only) you find :
. NVMREG access (Section 10.4 “NVMREG Access")
that explain how to write to flash and also to user id area.
And on table 10-3 it's explicitly indicate that user id area (0x8000-0x8003) is writtable. I know that datasheet has a lot of pages but I'm tring to read all of these, at least all of these involved on my program.



to Ttelmah:

of course write access to eeprom is easy but I've chosen, as in many PIC16 and PIC18 project (also PIC16F1825, very similar to PIC16F18325) to use user id, to storage my bootloadable program checksum, for safety reason, to put on a region not involved to my normal program. On PIC16F1825, where I've used CCS 4.132 at that time, I've seen that write_program_memory() api doesn't works (unlike on PIC16F19xx) and write_configuration_memory() was available only for PIC18, so I've written a procedure on my own, following datasheet assembly indication, to do the job and it works, so it's possible to write on user id. On CCS 5.061 I've noticed that write_configuration_memory() is availabe also for Enhanced16 and I hoped that CCS has covered that gap on there apis. Maybe there is some jobs to do on CCS side?

Regards and thanks for your response on my issue
Fabio

[Ttelmah]

Just worth adding, that the code example MicroChip, gives for writing to the User ID on this chip, doesn't work....

Probably explains why CCS have omitted it.

Then Table 10-2, disagrees with MicroChip's own comment in Table 10-3. If you look this shows for NVM access, for the User ID, config etc., 'READ', not 'READ WRITE'.....

Nothing listed yet in the errata about this.

[Ttelmah]

OK. Looking at the data sheet, the code given to supposedly access the ID, is the code to access program memory, not the ID....
Copying from a couple of other chips with the ID access, it looks as if this should be close to what is needed:

[ftoffolon]

Thank you very much Ttelmah,

this week I'm fully involved into other project but next one I'll try your example.

Regards

[ftoffolon]

Hi Ttelmah,

Finally I've found time to test your procedure. Unfortunately has no success. I've checked an old porject I've done with PIC16F1825, where I've implemented my proceudre to write User ID area. I've translated it with new registry names of PIC16F18325 (they are almost the same, only with different names) and it works !
Now I can write to user ID area.

Here's the procedure:

[Ttelmah]

Well done.

You can do the nop with: