Assembler: please kick me in the right direction

[Darrel Taylor]

I was thinking something more like this...

dph_save VAR BYTE
dpl_save  VAR BYTE

ASM
write_char:
    MOVE?BB  dph, _dph_save
    MOVE?BB  dpl, _dpl_save

    push dph <--- delete this line
    push dpl <--- delete this line
...

...
    pop dpl <--- delete this line
    pop dph <--- delete this line

    MOVE?BB  _dph_save, dph 
    MOVE?BB  _dpl_save, dpl 
return

...

ENDASM

And, here's a little more info on the MOVE macro's
http://www.picbasic.co.uk/forum/showthread.php?p=2009

.

[Demon]

What type of variables are the variables a, b and c considered? My first quess would have been a work register, but I'd like to be sure.

Since there are only 2 variables in the equation, the new command should be MUL?xx, right?

(available letters seen in your reply to PIC Beginner in other thread)

Robert

[Darrel Taylor]

This page describes the 8051 registers, but the whole site is pretty good too.
http://www.8052.com/tutbregs.phtml#R%20Registers

The MUL?xxx macro usually has 3 paramaters, the third one is the result of multiplying the first two.

For instance, if you had the following variables ...

A  VAR  BYTE
B  VAR  BYTE
Y  VAR  BYTE
Z  VAR  WORD

THEN ...

  this ASM macro              is same as this PBP statement
  ---------------------       -------------------------
    MUL?BBB   _A, _B, _Y          Y = A * B
    MUL?BBW   _A, _B, _Z          Z = A * B
    MUL?BWW   _A, _Z, _Z          Z = A * Z

And, you can see that often it's easier to just jump out of ASM and handle it in Basic.

------------------
If you do use the MUL? macros, there's something else you have to do to get them to work. Since, they are from the PBPPIC14.MAC file, they don't automaticaly get included with the project. So you have to Trick PBP into thinking it needs those macros.

This bit of code doesn't use any Program space since the ifdef keeps it from being compiled. But PBP sees the statements and includes any macros that are associated with them.

@  ifdef DoNotCompile                        ' Macro to include
       R0.LowByte = R0.LowByte * R0.LowByte  ' MUL?BBB
       R0 = R0.LowByte * R0.LowByte          ' MUL?BBW
       R0 = R0.LowByte * R0                  ' MUL?BWW
@  endif

But then, If you do it in Basic, you don't have to worry about it.

Merry X-Mas,
Darrel

[Demon]

I'm going with basic for the multiplication. Only problem is that table 4.1 in this document is confusing:
http://xess.com/manuals/asm51.pdf

The entry for MUL is:

B x A --> B,A

Ok, so what does that mean? The result is placed in both A and B? In addition, the result is accumulated in the first variable. I expected something similar, either in the first, or in the second, but not both. Obviously I'm misunderstanding something here.

I tried finding Note 7, but I can't see it anywhere.

Robert

[Luciano]

Intel 8051

(The result is sixteen-bit)

Multiplies the unsigned value of the Accumulator by the unsigned value of
the "B" register. The least significant byte of the result is placed in the
Accumulator and the most-significant-byte is placed in the "B" register.


---------------------------------------------


MCS 51 Microcontroller Family User's manual. (15 MB file).
(Original data-book scanned).
See PDF page 90
ftp://download.intel.com/design/MCS5...S/27238302.pdf

* * *

8051 Instruction Set (300K file).
See PDF page 50
http://batronix.com/pdf/befehle.pdf

* * *

80C51 family programmer’s guide and instruction set. (270K file)
See PDF page 43
http://www.logiccell.com/~jean/8051/3082.pdf

* * *

[Demon]

Thanks for all the replies.

I still have to control individual characters, contrast and the touch screen, but I got it to work. I printed xF0 across the entire LCD, to make it easy to see output. I have the LCD on inverse in this example, the top of the line should be high, not the bottom.

The Hantronix code is incomplete for an Optrex LCD, you have to scour through the Optrex code and add missing control codes. Once I get the characters to come out properly, I'll see about putting out a bitmap.

One idea I'm toying with is rotating the LCD and printing in portrait instead of landscape mode. There are applications where I want a vertical LCD instead of horizontal (like a list of single-word commands).

I'll post the code once I've sufficiently changed it and made it my own. I don't want to be bothered with Hantronix and copyright laws.

Robert

[Demon]

There you go:

http://www.picbasic.co.uk/forum/showthread.php?p=16269

Robert