How can I speed this code up? SHIFTOUT is slowing it down and I need a faster way.

[mackrackit]

131,072 SHIFTOUTs in that loop and it is shifting the same value 15 times, getting another value and shifting that 15 times, again ,again.... That will tale some time.

Unless I am looking at it cross eyed...

Is the above really what you want to do?

[wolwil]

131,072 SHIFTOUTs in that loop and it is shifting the same value 15 times, getting another value and shifting that 15 times, again ,again.... That will tale some time.

Unless I am looking at it cross eyed...

Is the above really what you want to do?

Yes but not 15 times 16 times and really its not all that bad if I would be able to have it shifting say at 1MHz or more

[mackrackit]

I wonder if SHIFTING all 16 values at once would be faster than looping? Darn zeros

shiftout dpin,clk,1,[DATA,DATA,DATA,DATA,DATA,...]

[wolwil]

I wonder if SHIFTING all 16 values at once would be faster than looping? Darn zeros

shiftout dpin,clk,1,[DATA,DATA,DATA,DATA,DATA,...]

I dunno let me try it...

[wolwil]

Nope The Same

The part that is slow is going from SUB1 to SUB2 not the looping through them 4096 times

I just tried taking out the GOSUB's and still the same thing

[Gusse]

There are couple of workarounds available:
1) changed crystal to 20MHz
2) If Shiftout command is too slow

<code><font color="#000000">    <b>SHIFTOUT </b>dpin,clk,1,[Dat]
</code>

then don't use it. Do it other way (e.g code below).

<code><font color="#000000">    dpin = Dat.0(7) : clk = 1 : clk = 0
    dpin = Dat.0(6) : clk = 1 : clk = 0
    dpin = Dat.0(5) : clk = 1 : clk = 0
    dpin = Dat.0(4) : clk = 1 : clk = 0
    dpin = Dat.0(3) : clk = 1 : clk = 0
    dpin = Dat.0(2) : clk = 1 : clk = 0
    dpin = Dat.0(1) : clk = 1 : clk = 0
    dpin = Dat.0(0) : clk = 1 : clk = 0
</code>

This will run much faster but consume more code space. Trade-off that you have to live with.
BTW, DATA is reserved word so therefore I changed it to Dat

BR,
-Gusse-

[wolwil]

<code><font color="#000000">    dpin = Dat.0(7) : clk = 1 : clk = 0
    dpin = Dat.0(6) : clk = 1 : clk = 0
    dpin = Dat.0(5) : clk = 1 : clk = 0
    dpin = Dat.0(4) : clk = 1 : clk = 0
    dpin = Dat.0(3) : clk = 1 : clk = 0
    dpin = Dat.0(2) : clk = 1 : clk = 0
    dpin = Dat.0(1) : clk = 1 : clk = 0
    dpin = Dat.0(0) : clk = 1 : clk = 0
</code>

BR,
-Gusse-

Nope the same.

20 MHz Clock will still be too slow with SHIFTOUT.

I am assuming your code has something to do with accessing per bit in the word sized Dat variable. So if I wanted to access the 11th bit I would do this Dat.1(2) right?

Would anyone have a faster way in Assembly I could do this?

Also Does anyone know how many clock pulses SHIFTOUT uses?