Assembler: please kick me in the right direction

[Demon]

Luciano, I did. The stamp link uses the serial interface; I'd much prefer to use the parallel interface. Unless I am mistaken, that should have faster response time. The Circuit cellar example uses C, nice stuff, but nothing I can use without learning a lot of stuff. Plus, the code I have is for a 51553 demo board, exactly like the one I have on hand.

Switching to a character LCD is not an option. That would mean basing my design on an obsolete part, not interested. Figuring out how to add a touch screen would complicate matters even more. Right now I have a solid source of gLCDs with mounted TS at an excellent price.

I'm not exactly starting assembler from scratch either. I was top of my class, only problem is that I graduated in '83. I have references for both 8051 and PM assembler, most of the commands are easy to convert. I'll just have a few questions on the exception cases.

That being said, would you happen to have an idea on how to convert the absolute call?

[Luciano]

Hi,

See this demo board:
http://www.tvielectronics.com/Produc...ontroller.html

The TC51553 Demo board has an option to store the data in a serial eeprom.

When this option is used, the on-board ATmega16 (9.216 MHz) reads the data
from a serial eeprom and sends it to the Optrex F-51553 LCD using a
8-bit parallel interface.

The Data Transfer of the Optrex F-51553 LCD is selectable serial
or 8-bit parallel. If your data is stored in a serial eeprom the
use of the parallel interface is not going to make a big speed difference.

* * *

Write a library for a Graphic LCD is a complex and challenging task.
Doing that in assembly is going to be difficult and time-consuming.

The assembly code you have posted is just a simple demo.

Some of the functions of a Graphic LCD library are:

- Clear display
- Set/Reset single pixels
- Draw lines
- Draw boxes
- Draw circles
- Write text with different styles and sizes
- Show a picture
- ....

Example:

CIRCLE x,y,r,c

x = Starting horizontal location
y = Starting vertical location
r = Radius of the circle
c = Color of the circle

* * *

I wish you a Merry Christmas and a great success with your assembly project.

Best regards,

Luciano

[Darrel Taylor]

would you happen to have an idea on how to convert the absolute call?

The easiest way is probably to use the L?CALL macro. That way, no matter where the destination is, the correct page bits will be set.

L?CALL destination

.

[Demon]

Luciano, I have that document. That is the one I am using to manage the 4-wire touch screen circuit.

I am using the schematic for the Optrex demo board from Apollo Display as a base for the LCD circuit. The charge pump circuitry is probably identical, I didn't bother comparing. Since I got the gLCDs from Apollo, I'm going to use their schematic, I also find it a bit easier to read.

I have no doubt that writing a library for a gLCD is complex, but I'm not doing that, I'm just modifying a working example. If I was able to progam software for banks, credit cards and utility companies for 20 years, it's not unrealistic to believe that I can convert an assembler program. As it is, I understand 90% of what is happening within this code.

As for the complexity of using all the functions of a graphic LCD, I never said I was going to use them.


Thanks for answering my question Darrel, much appreciated!

[Demon]

I've Googled, but I can't find a place with nice PM assembler code. I'm particularly interested in how the I/O pins are addressed.

How to move a byte to a port:
mov P1,a ;set output data

How to reset a particular pin:
clr P3.2 ;CS = 0

Robert

[Demon]

I finally found a nice example here:
http://picbasic.com/resources/articles/brainart.htm


setb rp0 ;change to register page 1
mov trisb,#00001111b ;make the bottom 4 bits on PortB inputs and the top 4 outputs
clrb rp0 ;change back to register page 0
;
clrb portb.4 ;start with output low and LED off
;
loop jnb portb.0,loop ;jump to loop if switch on PortB.0 is low
jnb portb.1,loop ;jump to loop if switch on PortB.1 is low
;
; if we got here then both switches are high
;
setb portb.4 ;set output high to turn on LED


Robert

[Demon]

Ok, I've researched each instruction and these 5 have no direct translations:

PUSH, push direct byte onto stack
POP, pop direct byte from stack
MUL, multiply
ADDC, add into accumulator
MOVC, move code byte to accumulator

I wouldn't be surprised if the equivalent PIC Macro instructions are staring me in the face, but I don't want to start guessing. Here is some code to show the context the commands are used in:

; write an ASCII character to the display
; The font file starts at ascii 32 (blank). The default font is 8x8 pixels
; INPUTS - character in register A
write_char:
push dph
push dpl
clr c
subb a,#32 ;ascii font with blank
mov b,#8 ;multiply by 8 (8 bytes/char)
mul ab
add a,#low(font) ;add to font table address
mov dpl,a
mov a,b
addc a,#high(font)
mov dph,a
mov r0,#8 ;8 bytes/char
wbyte: clr a
movc a,@a+dptr
acall write_data
inc dptr
djnz r0,wbyte
pop dpl
pop dph
ret

8051 assembler reference here:
http://www.ece.umr.edu/computing/uni...e/tasking/asm/

PIC Macro assembler reference:

Robert

[Darrel Taylor]

Robert,

The PUSH and POP were apparently used to save 2 variables that were used in the write_char: routine. You can just use separate variables to temporarily store the two bytes, instead of trying to use the stack.

MUL can be replaced with the MUL?BBB or MUL?BBW macro.

For the addc and movc, you can either manipulate the EEADDR, EECON and EEDATA registers manually, or you could break out of ASM and use the READCODE statement to get the byte first, then do the ADDWF or MOVWF.

HTH,
Darrel