Bebe Thank you!

You beat me to there.

Sounds like 'the tortoise and the hare'.

Let me ask my little tortoise like question.

movlw b'1101'

Does this lay the values into the 8 bit address just like you see it?

I am talking about the little 8 box picture you see a lot.

With boxes numbered 0 to 7. Left to right.

Since there are only 4 digits here.

Where does it end up. On the leftmost or rightmost?

 

0000 0000 that becomes 0000 1101

 

Since there are only 4 digits here.

Where does it end up. On the leftmost or rightmost?

Rightmost, in the four least-significant bits of wherever you're putting it.

 

Bebe

You beat me to there.

Sounds like 'the tortoise an hare'.

Let me ask my little tortoise like question.

movlw b'1101'

Does this lay the values into the 8 bit address just like you see it?

I am talking about the little 8 box picture you see a lot.

With boxes numbered 0 to 7. Left to right.

Since there are only 4 digits here.

Where does it end up. On the leftmost or rightmost?

...jumping in....

My advice is to NOT overthink it. If you want to know what the instruction does, look it up in the chip's data sheet....
MOVLW
Move literal to W
Syntax:[label] MOVLW k
Operands: 0 <= k<=255
Operation:
k->(W)
Status Affected: None
Description:
The eight-bit literal ‘k’ is loaded into the W register. The “don’t
cares” will assembled as ‘0’s.

movlw b'1101' is the exact same assembled instruction as movlw b'00001101' as movlw 13 as movlw h'0d (or 0x0d whatever the syntax). You are always loading eight bits into the W register. With some experience you will see that right away. When I code, I sometimes will use all eight binary bits just to remind me - especially if I am dealing with a lot of cases where I am not dealing exclusively with eight bits. That is, I suppose, a style option, but understanding the instruction is not.

 

I have had problems with b'1xxx'
Not doing what's you wanted
So I stopped taking the easy way out
And just write the whole byte.

 

I am talking about the little 8 box picture you see a lot.
With boxes numbered 0 to 7. Left to right.

The bits on a PIC are numbered 7-0, left to right, MSbit to LSbit. It will make a difference when you use bsf/bcf as those instructions refer bit numbers.

 

Yes John it dose bit bites you

 

Thank you Bebe OBW and Raymond!

One more question about this and I will move on to next mini subject.

Is it safe to say you are after the 'pattern' not the actual 'number' or 'sum'?

Example: '0000 1000' puts a 1 in that position and the compiler or program reads the byte

looking at all 8 positions

That position has significance?

Another example: 1000 0000

Assembler is not really interested in the amount just what is in the '0' bit or first

position?

Using 0-7 numbering left to right.

EDIT Maybe better to say 'First, Second Third...' position.

 

Note: Wrote my post before these last two responses by Bebe and John.

Edit

Oh oh! Looked in 10F200 data sheet SFR register section.

Microchip DOES 'countdown'. Numbers 7-0.

My questions still stand though.

 

Right to left position has significance
Port's are 0 to 7
Porta0 Porta1 Porta2 so on If you want to say make PORTA0 high you'd write B'00000001' to PORTA or GPIO
Just depends on which port's your chip has.

The baseline chips work better writing the GPIO all at once.

movlw b'00000001'
movwf GPIO

It's like this if you start at 0 and end at 7 could you get there without a 0
No cause you have to start at 0 and move left


Reading is a whole new story.

 

You just got have fun Bob

 

Thank you Bebe!

Okay. I will put LED and resistor back on the correct pin.

Then compile and run this program.

Then call it good.

Wait until you see next lesson!

I need to break lock on the .PDF lessons.

Have to cut and paste parts of it.

 

Well.Before I move on.

What is the TRIS register?

I will look at the 10F200 datasheet.

 

It sets input or output

movlw B'11111111'
 movwf     TRISGPIO ///all pins input
movlw B'00000000'
 movwf     TRISGPIO  ///all pins output

 

And be in the habit of setting TRIS with movwf rather than flipping individual bits. Many PICs have issues/conflicts with single bit flips on TRIS.

 

Bebe and John

Thank you!

Will respond tomorrow.

Note Datasheet is a 'Secured' .PDF document too!

Can't cut and paste from that!

 

Note Datasheet is a 'Secured' .PDF document too! Can't cut and paste from that!

I have no trouble copying and pasting text from data sheets (whether opened in my Chrome web browser or in Adobe Reader), even though Adobe Reader shows them as "SECURED". It doesn't always come out very pretty when pasted, but it does work. For example, here's a screenshot of a portion of a page from the dsPIC30F3013 data sheet, with text selected:



Hit CTRL-C to copy, then come over here to the comment edit window and hit CTRL-V to paste, and voila:

2.4.1 MULTIPLIER The 17 x 17-bit multiplier is capable of signed or unsigned operation and can multiplex its output using a scaler to support either 1.31 fractional (Q31) or 32-bit integer results. Unsigned operands are zero-extended into the 17th bit of the multiplier input value. Signed operands are sign-extended into the 17th bit of the multiplier input value. The output of the 17 x 17-bit multiplier/scaler is a 33-bit value which is sign-extended to 40 bits. Integer data is inherently represented as a signed two’s complement value, where the MSB is defined as a sign bit. Generally speaking, the range of an N-bit two’s complement integer is -2N-1 to 2N-1 – 1. For a 16-bit integer, the data range is -32768 (0x8000) to 32767 (0x7FFF) including ‘0’. For a 32-bit integer, the data range is -2,147,483,648 (0x8000 0000) to 2,147,483,645 (0x7FFF FFFF).​

Like I said, it might not be very pretty due to the text formatting being lost, but it does work.

 

OBW

Thank you!

No dice!

Just gave it a whirl this morning with datasheet and just got what I had copied

from last using it.

I'll figure it out.

It's windows 7 upgraded to Windows 8.1.

Newest Adobe Reader. Acrobat maybe.

 

Get windows 10
And never look back

 

Get windows 10
And never look back

I have it on my lap top and find it cumbersome to use, and retro-grade in some areas..
The PC I use the most is XP and am most used to it I guess.
Max.