PICAXE Memory Map and SFR Details Chart

westaust55

Moderator
I have corrected a minor error in the PICAXE Variable & memory Map sheet covering nearly all current PICAXE chips.

Additionally I have developed a more compact (if 5 pages can be called compact) table/chart detailing the functions of
the SFR registers in Banks 0 and 1 which are accessible from within PICAXE BASIC programs using the PEEK and
POKE commands. This excludes the general purpose RAM locations.
This is likely a little more orientated to the 28X1 and 40X1 chips but the majority of registers do have the same function in each PICAXE and exclusions for particular PICAXE chips are noted on the right side of the third column (in the green shaded portion).

Thought this table/chart may be useful to others as I have noted that many do not download the PIC datasheets.

A 5-page summary is considerably more compact for quick reference than a several hundred page datasheet for most purposes.

Keep in mind that use of these registers or changing the various bits is at the users own risk.
I take no responsibility if you corrupt data or cause other problems.
Ultimately those who are really interested should still download the relevant PIC datasheets for a more complete description.


EDIT1: Please note that there is an updated version (V8) of the variable map only at post 10


EDIT2: A first-pass 18M2 SFR Data sheet is now available at post 13 (page 2 of this thread)
 

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manuka

Senior Member
Top marks on your concentrating skills! Any old fool can produce 200 pages of data- it takes a genius to concentrate it down. This is likely to be a valuable PICAXE resource, although even at 5 pages still quite an eyeful. I like your choice of colours, but these may mean B&W laser printing issues,so worth advising that colour inkjet printing best suits.
 
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westaust55

Moderator
Thanks for the feedback and comments Manuka.

There is still a lot of info in that 300+ page datasheet describing operation but by the same token, for PICAXE users, we cannot access half of the SFR registers thru PEEK and POKE so my sheet reflects just those that we can access.
 

kevrus

New Member
Very nice job. I for one, find pic datasheets extremely hard going so this seems to simplify the 'relevant' bits (no pun intended) for us simpletons who only occasionally may wish to peek at or poke something...now that sounds rude
 

manie

Senior Member
@Westaust55:
Thanks for your GREAT contribution. I for one, as a real NEWBIE a few months ago, had to store values as thjere are not enough user variables in the 28x1. What a shlep to find this out if you really don't know much. Having struggled through it then, your tables will mean something to me NOW, at that time (learning memory basics) it would maybe have helped. What I'm saying is this:

RTFMF !! R(ead) T(he) F(lippin) M(anual) F(irst) ! You must understand the basics of it before a work of ART like these tables will help you....

To all newbies, Refer to paragraph above. If all else fails, THEN RTFMF again !!!
Manie
 

manie

Senior Member
But ALL newbies read the manual.
Not quite an oxymoron ;)
The last word there is "AGAIN", thats when you start to discover and understand... I consider myself a real NOOB. I have to read a few times and sort it out along with OTHER stuff in the manuals. When it comes together it tends to go CLICK..
 

Janne

Senior Member
Oh man, tuesday i just printed out 7 A3 copies in colour of your version 7 memory map.. And now you decide to update it. ;)
 

axeman22

Member
These memory maps take some reading to get familiar with, but just like Unix Man pages.. they're invaluable - top Job!

I would suggest the addition of the DS3232 - a much better clock than the DS1307 IMHO.
 

westaust55

Moderator
18M2 SFR data map -first attempt

Based upon the PIC16F1827 datasheet which has been referenced as the nominal basis of the PICAXE 18M2, I have prepared the attached SFR data table which others may also find helpful if delving into the control of the 18M2.

Since this is based on the PIC16F1827 datasheet, there may be errors :eek: but it is a starting point for the 18M2. If nothing more, it distills around 220 pages of SFR data in tables and words (in a 406 page document) into four A3 sized pages (you will not read it at A4 size).
 

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boriz

Senior Member
Grateful for your efforts Westy. Any chance you could put this on a webpage? It would make it easier for me to be sure I’m looking at the latest version of the info.
 

fernando_g

Senior Member
Westy;
there is only one thing missing from your tables.....your signature!

They are masterpieces, and as such you should sign them.
 

westaust55

Moderator
At this time, the answer is no.

Maybe something I will get around to when I finish my first round of experimenting with Nokia mobile phone colour gLCD modules.
So many projects, so little time...
 

Armp

Senior Member
OK thanks. I just didn't want to make a map if one already existed.

I'll forward any worthwhile results to you.
 

Technical

Technical Support
Staff member
Registers are in identical positions on all M2 parts, so one chart would fit pretty much fit all.
 

westaust55

Moderator
Thanks for that info Technical.
I had, long ago, downloaded corresponding datasheets for the later M2 parts.
Your information would pretty much obviate the need for extensive research.
 

westaust55

Moderator
PICAXE Memory Map V9

The attached PICAXE variable map has been revised to capture hopefully all of the changes relating to the M2 series chips

EDIT: updated as per typo noted below by Armp in post 25.

EDIT2: PLEASE BE AWARE THAT THE STATEMENT AT THE TOP OF THE BASIC ACCESSIBLE RAM / SPECIAL FUNCTION REGISTERS (SFR's) has a minor error.
For the statement: For M2 parts bptr/@bptr can access > address 255
that should exclude the 08M2 which is limited to an upper memory location of 127 ($7F) - as stated in PICAXE Manual 2 on Page 14.
 

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Armp

Senior Member
Fantastic effort - thanks!

For M2 parts ptr/@ptr can access > address 255
Should be bptr maybe?

I'm struggling a little bit with the SFR/RAM allocation for the 20M2 - I guess I need to take another look at docs.
 

westaust55

Moderator
Fantastic effort - thanks!

Should be bptr maybe?

I'm struggling a little bit with the SFR/RAM allocation for the 20M2 - I guess I need to take another look at docs.
Thanks for the typo spotting. Will fix later today.

For the M2 SRF's, have you looked at the table at post 13?

EDIT: table at post 24 now corrected.
 
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fernando_g

Senior Member
I join the chorus thanking you for your efforts. Compiling all the scattered data is very valuable.

One observation, though: on the DS1307/ DS1338 register map you are missing the very last row, perhaps because of truncation when the spreadsheet was converted to PDF.
The missing register description 07H, is the one that controls the square wave output.
 

Janne

Senior Member
A friendly bump and a thank you for the chart. Came here as I needed a new print, I had an old one printed in full color A3 but that seems to be one more item lost on the last move :)
 
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