Dual bipod winch foam cutter

In practice actual step time isn't set by the stepgen step_len parameter, but by the parport reset_time parameter. There is a function of the parport driver where a programmable time after setting the pins to the new configuration it sets pins in the reset mask back to zero. stepconf uses this (line 805) as it means you can have double the step rate.

It is worth noting that "Reset" actually freezes the machine in a busy-loop waiting for the time to expire. The driver limits the wait to 1/4 the base period. If you need more than 1/4 the base period then you probably need to increase the base period to suit the driver. This probably actually gives better step and cpu performance.

setp parport.0.reset-time 5000

Brian,

Just to avoid any further confusion on our part you have ..

Run Latency test for an extended period.
Taken the results of the Latency test and the timming praramters for your drivers and run them through Stepconfig on ficitious machine.
Taken these results and checked/editied your machine configuration.
Tried these and checked if the Scale is right (command 1" movement and machine moves 1")
Checked to make sure you are appling the correct amps to motors.

And motors run but not smooth.

Rick G

bvandiepenbos wrote:

I am still confused.

I have been looking at the stepgen source, and I am now a little less confused.
git.linuxcnc.org/gitweb?p=emc2.git;a=blo...1742086cfbb5;hb=HEAD
Line 709 onwards.

Basically stepgen chooses a base period such that the period is long enough to not need more than one thread period per step. This makes sense, as the base period can be adjusted to nanoseconds, whereas if you are using multiple thread periods per step the resolution is in tens of uS. Whilst step_time is nominally in nS, setting it to 1 just means that it is set high when stepgen runs and there is a step request, and then low next thread execution.
In practice actual step time isn't set by the stepgen step_len parameter, but by the parport reset_time parameter. There is a function of the parport driver where a programmable time after setting the pins to the new configuration it sets pins in the reset mask back to zero. stepconf uses this (line 805) as it means you can have double the step rate.

The setup and hold time parameters are calculated in line 719/720 and seem to be the number you put in the boxes + the latency you put in the latency box. Does that fit?

andypugh wrote:

In practice actual step time isn't set by the stepgen step_len parameter, but by the parport reset_time parameter. There is a function of the parport driver where a programmable time after setting the pins to the new configuration it sets pins in the reset mask back to zero. stepconf uses this (line 805) as it means you can have double the step rate.

I´m the german fellow ....
just one comment: I use a home made board with a TBA6560 too, and I disabled the reset function, because the TBA6560 needs pretty long pulses. I think the hal, which is published at google code, is working with my TBA6560 hardware perfectly.

Gerd