SxSim & pipeline & clockcycle

Alessandro

Hi folks! how are you?
·I'm an italian student, i'm doing some benchmark on the sx28, it works fine but·both the Ubicom datasheet, and the Parallax ones are not telling the truth on the timing that i found.

I tried also to use the SxSim to understand but nothing.

Is possible to see the pipeline (fetch, decode, execute, write) on the simulator?

are in the SxSim some Known problem?

Thanks to all!

Alessandro

·

PJMonty

Allesandro,

SxSim doesn't show the pipeline stages, just each instruction.

You say that the datasheet doesn't match your timing. There are many people using the SX for timing critical work and no one has reported problems. Can you post some code that shows a difference between your timing and the datasheet?

Thanks,
PeterM

Alessandro

Thanks for·your answer!

To test·the speed and the clockcycle·i have put a led over the RB0 and through a 460OHM resistor to Vss.

The program to test the speed is simple:··it·turn the·led on and· than·turn it off.



Initialize··· ;Configure port settings

mov rb, #%00000000 ;Port·B output zero

mov !rb,#%11111110 ;Port B.bit0 output dir.

;

---

MAIN PROGRAM

---

Main

mov rb,#$01

mov rb,#$00

jmp Main ;goto main



on 4 MHZ turbo, the high period is 470 ns, and the low period is a bit more because of the jump time.

Now on 4 MHZ the clock cycle is 250 ns, and the datasheet says that the move istruction takes 1 clock.

but it is longer! what is wrong?



Thanks again

Alessandro

Bean

The "MOV rb,#" instruction is a compound instruction.
It is actually TWO mov instructions.

MOV W,#$01
MOV rb,W

So it takes 2 cycles.
To make a 1 cycle pulse, use SETB and CLRB.

Bean.

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Post Edited (Bean (Hitt Consulting)) : 3/9/2008 10:01:16 PM GMT

Alessandro

YEA! You are right, i love forum moderators

thanks a lot!

Alessandro (Italy)