at 50% power it is about 8mA
something that happens is when the machine is engraving I increase the speed the power reduce! sometimes it is like the co2 tube is off!
Does the power only reduce at corners? Or even in long straight cuts? If at corners this may be due to variable power to account for acceleration/deceleration.
Make sure that your machine is actually capable of achieving the speeds that you’re setting. You may be able to increase the acceleration setting on the controller to also mitigate this.
This isn’t making sense…
At 100% you read 30mA? … did I miss something?
8mA seems very low, I’d expect about 15mA at 50% pwm.
I guess the question is how is this being measured…
too much problem at high speed
first,the power reduces in long straight engrave or cut
second,it is like it loses the steps because for example if you are engraving a 40x40 Square in high speed it is look like it is engraving about 70x70 Square
yes at 100% 28mA but 50% it is about 8mA!
It sounds like you have a bit of tuning to do.
Have you calibrated your axes and tuned max speed and acceleration? If not, start with those.
I read through most of this and there was so much confusion created for such a simple issue and solution. I don’t know why ‘CMOS’ was even mentioned. It’s 3.3v TTL and 5v TTL.
Most LPS do not have the potentiometer do be able to adjust the scale back to 3.3v like OP’s does so I’m posting this here to help anyone else that comes across this.
The LPS expects an analog signal from 0-5v to set the power OR a 5v PWM signal.
Hence, running a 3.3v PWM signal into the LPS, you will only ever get ~60% power MAXIMUM
I have just gone through an almost identical process with my own but using an MKS Tinybee. I used a non-inverting buffer chip to convert the 3.3v PWM to 5v PWM and it works fine.
For reference, I used a 74AHCT125 which is a simple 5v, gnd, 3.3v TTL In, 5v TTL out chip - It can handle 4 inputs/outputs too.
Also - Be careful using the spindle ground output (screw terminals) for anything related to the LPS enable signal - The ground will swing to the input voltage when ‘off’. The LPS may not be able to handle this voltage.
I also noted on mine that if the LPS EN is grounded on power up, the laser will fire for about 300ms before the MKS sets the TTL output low. I mitigated this with some relays in series, one NO, the other NC and using an Enable pin for the laser but I use FluidNC firmware which is quite configurable.
I highly recommend FluidNC over the default MKS firmware as it’s extremely configurable but does have a bit of a learning curve to get it working.
TTL is defined as a 0 to 5V voltage signal range.
If it doesn’t have that, it’s not TTL… That is half the battle here.
The IN to all of these I’ve used is not TTL it’s 0 to 5 volts, dc or pwm. In other words it’s not digital, it’s analog.
It can be driven by pwm if the pwm is actually at a ttl signal level.
The adjustment @Enzoo made doesn’t appear anywhere near linear enough to be useful. It should be in the ballpark anyway.
I have yet to think of a reason for this adjustment…
You’re sorta splitting hairs. Ok, yes, true TTL is 5v but in this instance, they are the same as far as the signal, just lower voltage. Technically it’s LVTTL but It’s certainly NOT cmos.
You’re sort of arguing with me but agreeing with me at the same time. Your statements are the same as mine but with different words.
At the end of the day, if the signal you’re giving it is only 3.3v, you’re only going to get 60% of the power without this adjustment pot (which most LPS don’t have) so the only way to do this properly is with a logic level shifter like i mentioned if you’re going to be controlling it with a 3.3v microcontroller like on the MKS DLC32.
It’s confusing when you say 3.3V ttl, since the 3.3V isn’t a ttl level. It’s just a digital signal.
If you wire something up with a 3.3V signal to a ttl device, it may actually work… as a 3.3V signal is usually above the threshold of a high state compared to 5V. That doesn’t mean the 3.3V signal is a ttl signal.
If the signal isn’t actually up to a 5V signal, it can never reach the 5V value required by the analog input to the lps.
This whole issue was created by making the assumption that the 3.3V is ttl, which it is not.
When you are trying to make this work, the devil is in the details.
The MKS DLC32 has a voltage translator on the pwm output to handle this, even though it’s only a one way translation.
Yes, I’m agreeing with the results, but disagreeing with the way you stated it… I think this adds to confusion when they read a 3.3V ttl.
All water under the bridge… don’t lose sleep over it… 
I sorta feel to the contrary - TTL probably means nothing to most people on this forum and is actually somewhat irrelevant in this discussion. It’s semantics really. We could completely leave out any form of it in this whole discussion and just treat it like you said - a digital signal at 3.3 or 5v that we are using PWM to simulate an analog signal. The fact that TTL is, or is not officially 5v is moot and is not relevant to this discussion in reality. The correct term we should probably be using is Logic Level. And if we’re honest, the LPS is not ‘TTL’, it’s just a 5v analog input.
It’s interesting that the board already has a logic level converter because by the looks of it, it’s not working for the OP - Perhaps some damage was caused somehow.
I have both the MKS DLC32 and an MKS Tinybee (Which is designed for a 3d Printer but runs my laser) so I am quite familiar with both but I have never tested the logic level output for the laser on the DLC32.
If you want to believe 3.3v and 5v is the same, we’ll have to agree to disagree.
TTL is defined as 0 to 5V, if it isn’t it’s not ttl compatible.
Since the whole problem here is that it’s not reaching the 5v for a ttl signal to the lps, I don’t think it’s moot, it’s the problem.
PWM is not voltage or frequency specific.
The Earth has approximately the same length of time in light as darkness. It’s a pwm that signals information to all kinds of animals/plants… It’s just got a slow rise and fall time along with a large period.
Good luck
I never said that at all - Quite to the contrary so I don’t know where you draw that conclusion.
Once again, irrelevant. You’re drawing the conclusion that because the LPS is expecting 5v that this means it’s ‘TTL’, when in fact it isn’t since it’s expecting an anlaog signal - There is no definition for vIH or vIL as there is with TTL Logic. That’s why i said TTL is irrelevant in relation to this thread - We’re simply talking about logic LEVELS.
The fact is, a logic 1 (or 100% duty cycle with PWM) from the ESP32 is only 3.3v so it can only ever reach ~60% of the expected 0-5v analog input signal to the LPS if driven natively.
I never said it was, I only made the statement that we simulate an analog output using PWM.
I have been involved with electronics for 30 years and spent the last 20 working with various microcontrollers, coding and designing circuits. I know what I’m talking about but all you want to get caught up on is the semantics of TTL officially being 5v logic levels which is irrelevant in this context because the LPS is not TTL anyway.
We must be talking opposite sides of the same coin… and not communicating.