Loops and Delays

jbumatai

I am looking for good samples of Loops and Delays for SX Assembly. I have read the pdfs and looked the code. I have a few but I would like to see some explicit examples of the right way to do a Loop and Delay as far as a starting point. Can I get a super simple example?

TIA
JBuma

Bean

One way is to use PAUSE in SX/B, then look at the generated code with RUN->View List.

Bean.

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David B

I can show you some samples of loops and delays, but I can't say they're good examples, or the right way to do it. But these work.

A good test is to run this in SxSim, put breakpoints in the NOPs, stop at the first, zero the microsecond time counter, run the enclosed delay routine to the second breakpoint, then see how many microseconds have passed.

These make no attempt to be really accurate but they're pretty good for general purpose delays.

If interrupts are enabled then they'll steal cycles from these, reducing their accuracy even more, but if the ISR is short I've had decent results even in that case.

David

;

---

device SX28, OSCHS, TURBO, STACKX, OPTIONX
IRC_CAL IRC_FAST
freq 20_000_000
reset start_point

org $F0
bank_assorted = $

t1 ds 1
t2 ds 1
t3 ds 1
t4 ds 1

;

---

; main program
;

---

start_point


:here
nop
call @delay1ms
nop
jmp @:here

;

---

; Jump table
;
org $600

delay1ms jmp @_delay1ms
delay10ms jmp @_delay10ms
delay100ms jmp @_delay100ms
delay1s jmp @_delay1s

;**************************************************************************
; delay functions

_delay1s
bank bank_assorted
mov t4, #100
:l1 call @delay10ms
djnz t4, @:l1
retp

_delay100ms
bank bank_assorted
mov t4, #100
:l1 call @delay1ms
djnz t4, @:l1
retp

_delay10ms
bank bank_assorted
mov t3, #10
:l1 call @delay1ms
djnz t3, @:l1
retp

_delay1ms ; delay 19304 cycles with "15" loop =~ 1 ms @ 20 mHz
bank bank_assorted
mov t2, #15
:l2 mov t1, #0
:l1 djnz t1, @:l1
djnz t2, @:l2
retp


;---the end

---

jbumatai

Bean (Hitt Consulting) said...
One way is to use PAUSE in SX/B, then look at the generated code with RUN->View List.

Bean.

Hello Bean, I never used SX/B so I do not know to run the code. Wierd, I know but I have only done the Assembly examples so far.

Peter Verkaik

There are many ways to create delays in assembly.
Take a look at this page:
http://www.sxlist.com/techref/ubicom/lib/flow/delays_sx.htm
Or use the delay code generator
http://www.sxlist.com/techref/piclist/codegen/delay.htm

regards peter

jbumatai

David B said...
I can show you some samples of loops and delays, but I can't say they're good examples, or the right way to do it. But these work.

A good test is to run this in SxSim, put breakpoints in the NOPs, stop at the first, zero the microsecond time counter, run the enclosed delay routine to the second breakpoint, then see how many microseconds have passed.
;

---

start_point


:here
nop
call @delay1ms
nop
jmp @:here

I am checking it. My only question is about the NOP: is that for testing only as you mention the breakpoints?

The code looks well thought out to me.

Thanks David.

Thanks Peter, I will check them out asap.

Post Edited (jbumatai) : 9/26/2007 12:55:01 AM GMT

David B

The only reason for the NOPs in the main loop was to make a convenient place to checkmark the breakpoints in SxSim.