Help please with Assembly (PBPro user)

[wjsmarine]

Hi folks,
I've steered away from Assembly as long as I could but am stuck with an old Application Note (AN715) that is exactly what I need - problem is the code is only available in the pdf complete with a bunch of other stuff in the listing.

I copied this across to a text file and laboriously edited out all the line numbers, etc. but can only get the errors down to about 37 (using MPASM 5.03). I don't know anything about Assembly so don't have a clue how to get any further. Long term plans will be to learn this but so far PBP has proven to be everything I need for a long time now.

Rather than look like a complete idiot contacting Microchip I thought I'd ask the Guru's on the PBP list for some help.

If anyone can offer some suggestions on removing the last of these errors it would be very welcome. I'm sure this is obvious to the educated but I'm completely in the dark here.

Kind regards to all members.
Bill

[ScaleRobotics]

I am not so experienced at using assembly, but with the help of Darrel, I have been able to get two microchip asm examples to work. (Thanks Darrel!!!).

This example looks a little more straight forward, but then they always look easy, don't they?

First, you should define your variables. This I have always done outside the asm portion.

;example:
T1XHi        VAR byte 
T1XLo       VAR byte 
..................................etc


;When these variable are used inside asm, you add a little "_" on the front of them:
asm
..........  _T1XHi
........... _T1XLo

endasm

Why don't you start with that, and see how many fewer errors you get. Then post your errors here, and I will try to help you.

[wjsmarine]

Hi scalerobotics,
Thanks for the assistance, I'm sure there are a lot of users out there that are interested in this and will learn as well.

So are you saying instead of trying to assemble the list as I am, use PBP and paste it in between a Asm and Endasm statement, while declaring the variables up front before that? Or do you mean use _T1X, etc, in the listing without PBP?

Cheers,
Bill

[Acetronics2]

Hi, WJS

Rather than look like a complete idiot contacting Microchip I thought I'd ask the Guru's on the PBP list for some help.

You wouldn't look like an idiot posting your query on Microchip users Forum ... And you could find people having played with this AN before ... Eventually used to asm too, ...

NOW ... browsing the Parallax site, you could discover ( oh surprise ! ) that they have a Memsic 2125 accelerometer , with Application examples AND BS2 Code ...

Knowing the 2125 works in the PWM way like the adsl 202, AND BS2 code, which is PbP COMPATIBLE ...

Why are you still sllepingly staring at that post ....

Hurry up !!! ... LOL

Alain

[ScaleRobotics]

So are you saying instead of trying to assemble the list as I am, use PBP and paste it in between a Asm and Endasm statement, while declaring the variables up front before that? Or do you mean use _T1X, etc, in the listing without PBP?

Hello Bill,

From your previous post, it sounded like you were happy with the speed of programming with pbp, and that it could do almost everything you wanted. We should be able to get your tilt.asm working with pbp as an include file, which would let you add you own code in pbp and get the tilt sensor doing something useful.

To start with, you will need to define the variables. (of course, you will have to start with defining the osc, your ports, etc, just as you always do). I define the variables inside pbp, which lets them be used within the pbp, as well as the asm portions of your code. When you do this:

T1XHi VAR byte
T1XLo VAR byte

inside your asm, the variables need to look like this:
asm
movwf _T1XHi
movf _T1XLo, W
endasm

You can look at my first conversion as an example. This assembly used object code, and yours does not. That's why I think it will be a little easier. Check out:
http://www.picbasic.co.uk/forum/showthread.php?t=7502


Your code looks interesting. Would be glad to help if you decide to proceed.

Walter

[wjsmarine]

Hi Walter,

Thanks for the help. I'm going to have to work on this in the background unfortunately because of a sudden unexpected pile of work which has just descended (meaning from Above, if you know what I mean!) onto me. I'll get back to you as soon as I can clear some of the work and have some news. Thanks also for the link to your previous effort, very informative.

Thanks Acetronics for the pointer - I'll take a look but I think it best for my education to persist with the asm challenge as no doubt there will be other times when I will need to do something similar with asm code I come across.

Kind regards to all.
Bill

[ScaleRobotics]

I looked a little more at the assembly code you attached to your post. One drawback, it uses LCD code that is written for 4 mhz crystal which makes it a bit less flexible. This could be edited out and more code written for pbp, to be flexible for use with different pics. By the time you do that, maybe Alain is right, better to use code that is written in picbasic.

I looked at the parallax code, like Alain suggested. They are using a lookup table with a pulsin command. This could be done pretty easily. If you want to make it more exciting, you could use an tan-1 or arctan function. Oh, but picbasic does not have an arctan function you might say.... True, but Darrel helped me get a atan2(y,x) function working, and atan2(y,1) is the same as the tan-1 or arctan function!

What am I talking about?
Well, I did a few searches on angle tilt and got to Freescale Semiconductors AN3461
http://www.freescale.com/files/senso...ote/AN3461.pdf

And they mention using the arctan function to determine the angle:

theta = tan-1 (Ax/Az) and I believe that angle of Y = tan-1(Ay/Az)

A lookup table for the 10 bit a/d converter would be a bit long. And we can have resolution of about .3 degrees with a 10 bit tilt sensor value. (I know your tilt sensor does not work on A/D converter, but rather pulse width, but you could still use this formula).

Here is the atan2 code:
http://www.picbasic.co.uk/forum/showthread.php?t=10528

I will try to show an example in the next couple days.