Code verification errors 16F1847

[richard]

data sheet page 82

8.5 Automatic Context Saving
Upon entering an interrupt, the return PC address is
saved on the stack. Additionally, the following registers
are automatically saved in the Shadow registers:
• W register
• STATUS register (except for TO and PD)
• BSR register
• FSR registers
• PCLATH register
Upon exiting the Interrupt Service Routine, these
registers are automatically restored. Any modifications
to these registers during the ISR will be lost. If modifications
to any of these registers are desired, the
corresponding shadow register should be modified and
the value will be restored when exiting the ISR. The
shadow registers are available in Bank 31 and are
readable and writable. Depending on the user’s
application, other registers may also need to be saved.

[Art]

Are you sure you’ve changed the destination device in the project from the 18F to the 16F part?
The only reason I can think of to blame software being written to the device for the device not programming, is writing invalid data to the device.

16F devices have a 14 bit instruction set, and 18F have 16 bit instruction set. That’s not a hard rule, but generally true.
Given that it’s chopping one of the upper two bits off, that’s suspicious.
The first example you gave looks like a specific subtract instruction op code that is not supported with 16F.
They both have subtract instructions, but the 16F can’t subtract from RAM, and load the destination in a single instruction.

I’m a little baffled though because I wouldn’t expect an 18F hex file to be able to load in the programmer software when a 16F part is selected or detected.
Just in case, why not read the program hex from he 18F part and try to load that straight to the 16F part to check the result?

[wjsmarine]

Thanks Richard and Art,

I found the Automatic Context Saving info in the data sheet after refining the search criteria, that's a lesson learned first up.

The MeLabs website mentions paid upgrades but I don't see anything for free even if a licenced owner (I am) - I've emailed Charles Leo for clarification but he's overworked so not expecting a reply soon.

Art, there's some confusion with your last paragraph - I'm not loading an 18F hex file into a 16F part, both are different programs with different resulting hex files except the 18F programs the chip without any problems and runs on a breadboard faultlessly. The 16F programs but suffers those verification checks. As mentioned, the only changes are those concerning the DTInt's files differences between the two families.

I'm looking into upgrading MPASM to see if it changes things - what should I be looking for? The only reference I have to go by is I see on my laptop \PBP3\MPLAB\MPLAB Tools v8.85.msi that I can't remember installing... I'm assuming the MPASM v5.45 I see at the top of the compile box came from the msi install - or am I wrong? Is it MPLAB X I need to download and install or am I completely missing the plot here?

On another tack, if I buy an upgrade does it include the appropriate version of MPASM? If not, how does one ever know when or what version of MPASM is needed? Confusion reigns.

Thanks and regards,
Bill

[richard]

its all there on the melabs web site
http://pbp3.com/download_legacy.html

[Dave]

I have used a few of these 16F1847's to replace a few old 16F628's on a couple of REAL OLD projects... They work a treat...

[wjsmarine]

Hi Richard,

Charles also responded to my email and provided the same information, thanks to both of you although I'm still wondering why I couldn't find that info myself.

I downloaded and installed MPLABX, checked the appropriate box in the program options and recompiled the code for the 16F1847 (MPASM v5.77 now indicated). I am now greeted with error messages (not there when MPASMX unchecked):
"Message[303] C:\PBP\BILL'S RETIC.ASM 1191 : Program word too large. Truncated to core size. (5761)"
followed by another 77 lines of the same but with end number changes.

Does this mean the chip program space is not big enough? It compiles to 7789 words used while the 18F2620 compiles to 14146 bytes.

While I'm here... how does one capture/copy the results messages? I appear to highlight it (turns black) but ^c has no effect.

Thanks for your patience and sharing of knowledge.

Kind regards,
Bill

[richard]

"Message[303] C:\PBP\BILL'S RETIC.ASM 1191 : Program word too large. Truncated to core size. (5761)"
followed by another 77 lines of the same but with end number changes.

Does this mean the chip program space is not big enough? It compiles to 7789 words used while the 18F2620 compiles to 14146 bytes.

it sounds more like a calculated jump or memory offset has gone out of limits, maybe if you post the entire error message
but sometimes the clues are pretty vague

While I'm here... how does one capture/copy the results messages? I appear to highlight it (turns black) but ^c has no effect

its not quite a clean copy though