Tamas Rudnai wrote:
> 
> Guys, before you go till the first blood, take a look at that datasheet
> again. It could be confusing as in Table 4-1 and 4-2 does not even
> mention
> anything about paging with the FSR. In fact, with the 12F510 they even
> mention a wrong power-on reset value (100x xxxx, however only bit 5 is
> used
> as banking). The only indication that something is weird with FSR is
> that
> the upper 3 bits are not full set after the POR. Same mistake with the
> 12C5xx and 12F508/12F509/16F505 datasheets.

I suppose this is relevant to the discussion that comes up sometimes, when
someone says "RTFM", the response to that is that data sheets can be hard to
interpret.  I agree with that to some extent, but in this case I think that
Microchip have made it as clear as can be.

Where would I look for information about how banking works?  In the 12F510
data sheet, that's section 4.2, "Data Memory Organization".  It states "The
General Purpose Register file is accessed either directly or indirectly
through the File Select Register (FSR)."  This is the very statement that
started this discussion - clearly whoever wrote the 10F200 data sheet copied
that text from another device's data sheet (forgetting, as I did, that it
doesn't strictly apply to the 10F200).  But for the 12F510, that statement
about the role of FSR is there, where it belongs, and it's perfectly true.
It's also illustrated by a diagram: Figure 4-2 shows the 12F510 register
map, with the role of FSR<5> clearly shown at the top of it.

Now, you could argue that if you didn't happen to look at the section on
banking, you wouldn't know about the role of FSR in banking on the 12F510
(and similar baseline PICs).  But I'd argue that that's a pretty fundamental
part of the data sheet to look at - I normally glance that that, for any
PIC, to see quickly how the registers are laid out.

Anyway, I'll leave it here on this one!  :-)


David Meiklejohn




-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist