Raspberry Pi 4 and bad latency.. SOLUTIONS?

Hi guys!I am on a new Project and found a mesa 7c81 an 7i92 on the flewmarket... dont know why someone sell it on a flewmarket...i start reading about the 7c81 and look to my boxes and found a raspberry pi 4 b version with 8gb ram.. oki load the image for the sd card from the linuxcnc website and bring it up.i isolate cpu 1 2 3 but latency doesnt go down.

Any tips?
in the config i disable audio blueetooth and overclock to 6v and 2000mhz..

which information i can share to get the cow frome the ice?

thanks all


 

 

 

try this

I forget 1 thing.. i use a 64gb micro sd card from the brand kexin from amazon.

amzn.eu/d/hXGglyV

same values or i am wrong??


 


thanks

Much better, move on to wiring and making chips!
Keep an eye when starting LinuxCNC if it complains about latency, it shows a warning usually when enabling it or later during use.

Your latency is a pass, move on

on ny m73 i have a jitter of 1000... so what is the reason thst you say that this latency is good???? thanks

Assuming you use the 7c81's FGPA for stepgen and don't sofware step, you don't need a base thread so latency requirements is much relaxed. I'd be happy with anything under 130,000 with 200,000 at a pinch

or a 7i92... i payed for both cards 100 euros...

so for my information... on a normal pc like optiplex 3020m or lenovo m73 tiny.. i have latency under 2000... but i never looked this way in the histogram.

can you explain me the spike?! please

same values or i am wrong??

Note the missing spikes (colored in blue/red) at the extreme left and right of the graph.