P2 PASM 4xCOG Syncronize

pic18f2550

I would like to know how to get 4 COGs in lockstep.
My idea is to use GETCT() to load the counter value and wait in the PASM part until it expires.

PUB main() | mode
  sync := GETCT() {{ Start all COGs (16sec to overflow}}
  sync := sync+256_000_000 * 4 {{ wait 4 sec }}
  cog[1] := pha1.ini(@sync, @p_array1, @s_array1, 64, 64)
  cog[2] := pha2.ini(@sync, @p_array2, @s_array2, 64, 64)
  ...

DAT
sync
        mov t0, ptra
        addct1 t0, #0 {{ 2 }}
sync1
{{ ==== SYNC }}
        waitct1 {{ 2+ }}
        ...

Translated with www.DeepL.com/Translator (free version)

macca

Using waitatn ?
The 4 cogs starts with waitatn, the spin code issues a cogatn(mask) with the 4-cogs bit set (after waiting a bit to allow all 4 to load and start).

Just wondering.

pic18f2550

I still have to make some preparations in some COGs.
The syncronization comes only a little later in code.
(this is not present in the example above).

macca

You can use a variable to signal when the cogs are waiting, same technique used with P1.

Try this:

CON
    _clkfreq    = 160_000_000

VAR

    byte ready[8]

PUB main() | c1, c2, c3, c4

    c1 := coginit(16, @driver, @ready)
    c2 := coginit(16, @driver, @ready)
    c3 := coginit(16, @driver, @ready)
    c4 := coginit(16, @driver, @ready)

    repeat while ready[c1]==0 || ready[c2]==0 || ready[c3]==0 || ready[c4]==0

    cogatn((1 << c1) | (1 << c2) | (1 << c3) | (1 << c4))

    repeat

DAT

                org   $000

driver
                cogid   a       ' get our id and
                add     a, ptra ' use as offset into the table
                wrbyte  #$FF, a ' signal we are ready

                waitatn         ' patiently wait...

                getct   ct
                debug(UDEC(ct))

                jmp     #$

a               res     1
ct              res     1

JonnyMac

That's pretty neat, @macca.

Cluso99

I used the cnt to sync all 8 cogs in a p1 logging program. For that program i needed each cog to start precisely 1 clock after each other.

pic18f2550

PASM

                cogatn  #2

Keeps the COG #2 running?

Does this also work with multiple COGs at the same time?

evanh

Yes, it's a bit-mask rather than an ID number. Value #2 is bit#1 so cog#1 gets the event. If value was #3 then cog#0 and cog#1 both get an attention event.