Restarting stopped COGS (Power save mode?)
ozpropdev
Posts: 2,791
With all the discussion on COG allocation etc. across on the LUT share thread I thought I would bring up another cog allocation scenario to add to the mix.
When the start address S[19:0] of COGINIT is <$200 and D[5]=1 the cog can be restarted with the code already resident in COGRAM.
This works great as long as your aware that a restart also resets DIRx bits.
This demo code starts a cog, waits 4 secs then stops it. 4 secs later restarts it in a different location.
When the start address S[19:0] of COGINIT is <$200 and D[5]=1 the cog can be restarted with the code already resident in COGRAM.
This works great as long as your aware that a restart also resets DIRx bits.
This demo code starts a cog, waits 4 secs then stops it. 4 secs later restarts it in a different location.
sys_clk = 80_000_000 selected_cog = 5 dat org loc ptra,#@mycode coginit #selected_cog,ptra 'start cog waitx ##sys_clk * 4 cogstop #selected_cog 'pause cog waitx ##sys_clk * 4 coginit #32+selected_cog,#restart 'restart cog at different cogram address here jmp #here '==== code to stop/start ========= orgh $400 org mycode setb dirb,#0 setb dirb,#2 '<< lost on restart .loop notb outb,#0 waitx ##sys_clk >> 4 'fast flash jmp #.loop restart setb dirb,#2 '*** restore port direction bit .loop2 waitx ##sys_clk >> 1 'slow flash notb outb,#2 jmp #.loop2
Comments
Thanks for the reminder.
Will COGSTOP be lower power, than WAITX ?
COGSTOP stops all toggling within a cog.
So what is the predicted difference in power, between a WAIT and a COGSTOP COG ?
There will be much less toggling during a WAIT than occurs during running. The streamer may still be running, but the cog ALU is pretty much suspended, waiting for the WAIT to end.
Very good points!
I've proposed a COGFRZ state to cover this, in the other thread.
Probably better covered here.