I am using PIC 16f887.

When I enter the code in MPLAB it builds successfully.

In the view tab there is Memory Usage Gauge

Total program memory shown is 8192 and data memory is 368

Consumed program memory is 2197 and data memory is 0

The code is very big at the moment

When I put a few more instructions in my code the controller stops working

Is there any limit to the number of subroutines or to the number of instructions I can use with PIC16f887

If you have any idea please let me know

Thanks

 

I think you'd do better in another department. There is a section on microprocessors about 5 lines down from "chat".

 

@I think you'd do better in another department

I am not clear with what you said..

@There is a section on microprocessors about 5 lines down from "chat".

Where??????

 

When you get to 2048 instructions calls stop working properly so you have to start changing PCLATH to get calls to work above that.

 

@When you get to 2048 instructions calls stop working properly so you have to start changing PCLATH to get calls to work above that


How do I do that?
Is there any example you know of the same?????

Thanks

 

This thread belongs in the Embedded Systems and Microcontrollers Forum

 

Are you using C, Basic or assembler. If you are using C or Basic. It could be that your code is limited to 2Kbytes. And you have overlooked some compiler warning about this. However if you use assembler The PLATH setting may be worth looking into.

 

There is a page called "all about circuits forum". It has 15 departments listed. I think the 5th or 6th one down attracts more traffic about your question.

Look at the top of this page where it says, "Welcome RG23". Look to the left side of that line and click on "all about circuits forum" to get to the page with all the departments.

You might get more people that know about your needs by posting a question in the Programmers corner" or "Embedded systems and microcontrollers". More people watching will get you more ideas, faster.

 

@However if you use assembler The PLATH setting may be worth looking into

I am using assembler

I am not sure about the PCLATH settings though

If you have any idea do let me know

 

All this will be in the data sheet. Never program without it. It is your best friend.
http://ww1.microchip.com/downloads/en/DeviceDoc/41291F.pdf

 

Since you are using a lot of subroutines there is a high chance that you run out of stack space during execution. Keep the gosub within the stack capability of your MCU (If I remember correctly is less then 10 for your pic device)

Cheers

Alberto

 

Is there any limit to the number of subroutines

Normally PIC16Fxxx have 8-level deep hardware stack.This stack is not used for passing parameters of function rather this is a hardware stack which stores 13 bits value of PC (ProgramCounter) whenever you use a CALL instruction or an interrupt cause a branch.So the limit is 8 i.e.. you can call functions or subroutines 8 times in a series.Some compilers use different technique to overcome this,but in your case you are using assembler.

You didnt post your code,their may be some other problem which is causing this.

By the way,other guys are asking you to post this in :
http://forum.allaboutcircuits.com/forumdisplay.php?f=17

Good Luck

 

Is there any way I can move this thread to the desired place?

 

@Keep the gosub within the stack capability of your MCU (If I remember correctly is less then 10 for your pic device)

Do you mean the max no of subroutines I can use is 10??

 

Click on red triangle in top right corner...................................................................................................over here^

Ask bosses to move you.

 

You should find this page helpful:
http://www.piclist.com/techref/microchip/pages.htm
Another helpful page:
http://brunningsoftware.co.uk/high.htm
Try a Google search for PCLATH; you will find over 40,000 "hits".

 

@Keep the gosub within the stack capability of your MCU (If I remember correctly is less then 10 for your pic device)

Do you mean the max no of subroutines I can use is 10??

No, that means calling routines from other routines, or recursively calling the same routine, or "nested" calls.

 

When executing a CALL or GOTO, the low 11-bits are
loaded directly from the instruction opcode. The high
2-bits are loaded from bits 3 and 4 of the PCLATH reg-
ister. It is a good practice to pre-load PCLATH with the
high byte of the routine’s address before executing the
routine. This can be done as follows:
.
.
movlw HIGH Table ;load high 8-bit
movwf PCLATH ;address of Table into PCLATH
call Routine ;execute Call instruction
__________________________________________________________

i read the above content

tried to implement it but didn't work

 

I've never actually had to do it, but the method in the second link from SgtWookie looks very easy to use and maintain. Just find the biggest and least used calls.

 

.
movlw HIGH Table ;load high 8-bit
movwf PCLATH ;address of Table into PCLATH
call Routine ;execute Call instruction
__________________________________________________________

i read the above content

tried to implement it but didn't work

One problem with this method is that you have to add it to every call which makes the code messy and slows every call down. Also if the routine uses the value in the W register then you have to rework it. The other method you can choose which calls are affected and it doesn't mess up W.