I think thre is an error in the datasheet, se below.


Jan-Erik Soderholm wrote:
> Alan B. Pearce wrote:
> 
>> As a side issue of this, do the newly announced chips with the extended 
>> instructions have a deeper stack? 
>>
> 
> See : http://ww1.microchip.com/downloads/en/DeviceDoc/41364A.pdf
> 
>  From the rellevant sections :
> 
>  > 2.4 Stack
>  > All devices have a 16-level x 15-bit wide hardware
>  > stack (refer to Figures 2-1 and 2-3).
> 
>  > 2.4.1 ACCESSING THE STACK
>  > The stack is available through the TOSH, TOSL and
>  > STKPTR registers. STKPTR is the current value of the
>  > Stack Pointer. TOSH:TOSL register pair points to the
>  > TOP of the stack. Both registers are read/writable. TOS
>  > is split into TOSH and TOSL due to the 15-bit size of the
>  > PC. To access the stack, adjust the value of STKPTR,
>  > which will position TOSH:TOSL, then read/write to
>  > TOSH:TOSL. STKPTR is 5 bits to allow detection of
>  > overflow and underflow.
>  >
>  > During normal program operation, CALL, CALLW and
>  > Interrupts will increment STKPTR while RETURN and
>  > RETFIE will decrement STKPTR. At any time STKPTR
>  > can be inspected to see how much stack is left. The
>  > STKPTR always points at the currently used place on
>  > the stack. Therefore, a CALL or CALLW will write the
>  > PC and then increment the STKPTR, and a return will
>  > decrement the PC and then unload the PC.

That should probably read "...and a return will
decrement the STKPRT and then unload the PC".

> 
>  > 2.4.2 OVERFLOW/UNDERFLOW RESET
>  > If the STVREN bit in Configuration Word 2 is
>  > programmed, the device will be reset if the stack is
>  > PUSHed beyond the sixteenth level or POPed beyond
>  > the first level, setting the appropriate bits (STKOVF or
>  > STKUNF, respectively) in the PCON register.
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