On 1/10/26 14:02, Viesturs Lācis wrote:
sestd., 2026. g. 10. janv., plkst. 17:26 — lietotājs gene heskett
(<[email protected]>) rakstīja:
That's correct for the electronics best practice. Most TTL/FPGA logic
can sink ( > 20 mills ) lots more current than they can source ( < 10
mills).
So that is how I write my hal codes. Switch the - terminal in *.hal
file, put solid 5 volts on the + terminal. Invert the logic in the *.hal
file so a logic zero = ON.
Awesome, thank you for confirming!
One more small question - in case I misread the specs of the SSR relay
and if it takes more current than FPGA pin would be happy about, will
I fry only that pin or whole FPGA chip? Just trying to understand what
am I risking with.
Considering that most of that style SSR's trigger on less than 5 mills,
I might put a 100 ohm R in the - line from your board.
Below isn't related and may be TL;DR but something you may need
to be aware of:
I have recently had several instances of blown 6n137's (the high
speed opto Isolator in used in the step and dir inputs) of the
Hanpose 90 volt rated LC42 drivers which are supplied rail to rail 5
volt signals by the signal stealer pluggin put in the stepstick socket,
which w/o the current limiter fail shorted taking the output transistor
on a BTT Octopus Pro V1.1 board that drives the LC42, out also.
There I used 1/10 watt, 192 ohm R's in series with the - terminal
on a new driver. ( I had them) Hanpose has been advised of the
problem but I've not heard back what if anything they have done.
Existing stocks of the original $60 version have been dropped to a $20
bill so obviously there is a fix in the pipeline. These are "closed
loop stepper/servo's", much more precisely controlled than
normal steppers. The next generation of motors and controllers.
The smarts are in the drivers, all they need is the TP output in
step/dir format LCNC needs NO PID's in that path. The PID
is in the driver and its one microstep tite.
The error between the input step and the motors encoder output
controls the motor current, so they run lukewarm most of the time
as opposed to burn your hand hot.
If the error gets large enough to get near skipping a step, the
controller can use every amp the motor supply has to stop that
step loss. If required, the driver can reverse the motor to restore
it to the correct position, doing that in microseconds so the motor
still doesn't heat. The driver turns up the currant if you push it so
no separate holding current setting is needed. The motor runs on
only enough current to get to where its been told to go. On 72 volts,
6000 rpm isn't an over estimate of top speed, where on 24 volts,
1500 rpm might be tops. If it hits a wrench, stopping motion, that
loss of step can signal LCNC to stop in the next millisecond.
That's been tested many times but has never occurred while running
g-code here. The idea in that event is remove the blockage, pull the tool,
rehome the machine, put the tool back in and run from line to
continue the job. But since it's never happened, I don't know if
"run from line" works. Somebody else like Andy should advise me.
Viesturs
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Cheers, Gene Heskett, CET.
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