PIC16F883 write_program_memory() does not work

[soundscu]

I am debugging PIC16F883 code with the CCS bootloader included and have come to the following conclusions:

1. The "write_program_memory(addr, data, count);" statement in the bootloader code does not successfully write to flash memory. I have added printf() routines to the bootloader to print three info lines: (a)program memory contents before writing, (b)the new values to be written, and (c)the contents after writing. The before and after are the same, regardless of the new values that are being written.

2. SIOW sends the first line of the hex file, then reports "timeout while downloading". I presume it's supposed to see the returned XOFF byte from the bootloader and wait, but it times out instead.

These issues could very well be an oversight on my part, but I am stumped. I sure could use some help at this point. TIA. :)

Jim

[PCM programmer]

You need to post your compiler version. All versions are different.

[soundscu]

CCS PCM C Compiler, Version 4.042

[PCM programmer]

Post a short test program that shows the problem.

See these threads for examples of test programs:
http://www.ccsinfo.com/forum/viewtopic.php?t=28440
http://www.ccsinfo.com/forum/viewtopic.php?t=25112
Write a program that's similar to those (in style), but make it shorter.
For example, just write to the memory and then read it back
and display it.

When you write the test program, use the write_program_memory()
function in the same way that you're doing it in your program.
Declare the variables in the same way.

[soundscu]

Thank you for your suggestions. I've already begun making a very simple test program. :)

It's not finished yet, but I'm puzzled by the following:

When I compile this C code:

[soundscu]

Ok, I think I'm on to something.

I start with these lines of C code:

[PCM programmer]

A lot of your code isn't correct. It doesn't match what the data sheet
says, or what the compiler says for the 16F series chips.
For example, 0x1000 is beyond the available word address range of
the 16F883. You should write words to the 16F series, not bytes.

To see the CCS library code in the .LST file, you need to comment out
the #nolist statement at the top of the 16F883.H file.

However, given all that, and after making corrections, I agree that the
it doesn't generate any library code for the write_program_memory()
function. But then I changed the #include file to 16F887.H, which is
a related chip in same series. Then it generated the code.

This may mean that the Device Data entry for the 16F883 is incorrect.
Writing to program memory may not be enabled for this PIC, due to an
oversight in setting up the Device Data file. If you have the full IDE
(PCWH), you could look at the entry for the 16F883 and compare it to
16F887. See if there is a parameter or some setting that is disabled for
the 16F883. Then maybe you could enable it. If you don't have the
full IDE, or if that doesn't work, then contact CCS support and ask them
about it.

[soundscu]

When first creating this test program, I quickly put a 0x1000 at the top, before going back to check the datasheet. It's now changed to 0x800.

Thanks for explaining the #NOLIST directive, that's very helpful.

As noted in the datasheet (not very clearly, I might add), the 16F887 writes flash in 8 word blocks, while the 16F883 writes flash in 4 word blocks. Thus, not the same code.

This difference is correctly indicated in the CCS Device Editor, so I suspect the compiler does not properly generate code for flash access identified as "PIC16 8/32" (write 8 bytes, erase 32 bytes, i.e. write 4 words, erase 16 words). It works correctly for "PIC16 16/32".

Jim

[PCM programmer]

My advice is to contact CCS support about this.