Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Max encoder resolution supported #12

Closed
aaroncnc opened this issue Apr 14, 2021 · 56 comments
Closed

Max encoder resolution supported #12

aaroncnc opened this issue Apr 14, 2021 · 56 comments

Comments

@aaroncnc
Copy link

aaroncnc commented Apr 14, 2021 •
edited

So i am looking to add encoder support to my mill and was shopping around but before buy i had a few questions.
What would be the max supported PPR (pulse per rev) of the hardware.(skr 1.4 non turbo)
If my motor is running at 3,000rpm and i get a 2,500PPR encoder
3000(RPM)*2500(PPR)/60(convert to seconds) = 125,000 pulse a second.

Would that be to much for it to handle?
I know it may not be tested and i dont have very much experience.
I am looking at these BTW (https://www.aliexpress.com/item/32961497880.html?spm=a2g0o.productlist.0.0.3ae621a5ymVxfB&algo_pvid=c010e7f7-b79d-4248-8cf0-27db96f28711&algo_expid=c010e7f7-b79d-4248-8cf0-27db96f28711-5&btsid=0b0a556616184206137934196e3680&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_
)

maybe 100PPR would be better?
3000(RPM)*100(PPR)/60(convert to seconds) =5,000 pulse a second

I see on the data sheet the chip has a dedicated Quadrature Encoder Interface and they are broken out as follows on a skr 1.4 board
A phase pin 1.20
B Phase pin 1.23
Z/index pin 1.24
@scottalford75
Copy link
Owner

The Remora encoder software module runs in the base thread at 40kHz. The 2500 PPR would be too much for the software module to handle. 100PPR would be ok.

Interesting to know about the QEI module and it's pins are available on the EXP1 header. Not sure about the capabilities of the hardware module. Would be an interesting experiment when time permits.

@aaroncnc
Copy link
Author

Yea the doc sheet gives little info about the max rate and Google did not turn up much.
So if it runs at 40KHz I could step up to a 500ppm
3000*500/60= 25,000 or 25KHz
And the absolute max would be a 800ppr as that's 40KHz and 3k rpms
Now my mill only can do about 2.2k but I do want to go faster one day.

I wonder how much more the hardware one can run at.

@aaroncnc
Copy link
Author

aaroncnc commented Apr 15, 2021 •
edited

So i was looking at your code for encoders and i noticed that it only has support for cha/b but no z index pulse.
The Z/index pulse is a simple 1PPR
This is so when doing spindle sync you in theory could run the tap out then back in without cross treading as you could use the index pulse to locate the position of the spindle. or so i have read.
But maybe the pulse being slower could just be feed as a digital input?
3000*1/60= 50 or 0.05KHz
Also no one taps at 3K rpm more like a few hundred.

@aaroncnc
Copy link
Author

aaroncnc commented Apr 15, 2021 •
edited

did some more quick google searches and seems there is a project with support for this very thing.
https://github.com/exmachina-dev/LPC1768-libQEI

So i went and ordered an encoder to play with this some more.
https://www.amazon.com/gp/product/B084Z3PSQ7/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
Should be here on the weekend hopefully i can start testing it out sunday and by the end of next week have my mill all setup.

@scottalford75
Copy link
Owner

Hi, thanks for sharing.

The index pulse could be utilised with a Remora DigitalPin to expose it on the LinuxCNC side. The QEI module is a neat way to capture the encode but would need some work to get the info across to LinuxCNC. Porting the code to Mbed and then a wrapper module for Remora. I'm currently focused on stepper driver support but I'm keen to follow your progress on this one.

@aaroncnc
Copy link
Author

aaroncnc commented Apr 17, 2021 •
edited

My encoder came in but i am having issues setting up my HAL file
error
./remora-xyz.hal:68: Signal 'spindle-phase-a' of type 'bit' cannot add pin 'remora.PV.2' of type 'float'
Shutting down and cleaning up LinuxCNC...

#spindle DAC
loadrt scale count=1
addf scale.0 servo-thread
setp scale.0.gain 0.002
#net spindle-speed-scale spindle.0.speed-out => scale.0.in
net spindle-cw <= spindle.0.forward
net spindle-cw => remora.output.1
net spindle-speed-DAC scale.0.out => remora.SP.3

#Spindle encoder

loadrt encoder num_chan=1
addf encoder.capture-position servo-thread
net spindle-cmd-rpm     <= spindle.0.speed-out
net spindle-cmd-rpm-abs <= spindle.0.speed-out-abs
net spindle-cmd-rps     <= spindle.0.speed-out-rps
net spindle-cmd-rps-abs <= spindle.0.speed-out-rps-abs
net spindle-at-speed    => spindle.0.at-speed
setp encoder.0.position-scale 1200.000000
net spindle-position encoder.0.position => spindle.0.revs
net spindle-velocity-feedback-rps encoder.0.velocity => spindle.0.speed-in
net spindle-index-enable encoder.0.index-enable <=> spindle.0.index-enable
net spindle-phase-a encoder.0.phase-A
net spindle-phase-b encoder.0.phase-B
net spindle-index encoder.0.phase-Z
net spindle-phase-a <= remora.PV.2
net spindle-phase-b <= remora.PV.2
net spindle-index   <= remora.input.6

Config on board
{
"Thread": "Servo",
"Type": "PWM",
"Comment": "SpindlePWM",
"SP[i]": 3,
"PWM Max": 213,
"PWM Pin": "2.3"
},
{
"Thread": "Base",
"Type": "Encoder",
"Comment": "Encoder",
"PV[i]": 2,
"ChA Pin": "1.20",
"ChB Pin": "1.22"
},
{
"Thread": "Servo",
"Type": "Digital Pin",
"Comment": "Index",
"Pin": "1.18",
"Mode": "Input",
"Data Bit": 6
},

@scottalford75
Copy link
Owner

Hi, firstly you will need to use the matching PRUencoder component for LinuxCNC. It takes in the raw-count from the firmware encoder module. Just like the normal encoder module you set the scale and the component will output position and velocity.

https://github.com/scottalford75/Remora/tree/main/LinuxCNC/Components/PRUencoder

I've got an example on my workshop PC for encoder feedback for position control using the module. I'll share that as a starting point.

Give me 30min or so to get down to the workshop.

BR

Scott

@scottalford75
Copy link
Owner

This would also be a great config to share once you have it working!

@scottalford75
Copy link
Owner

Closed loop config example has just been pushed to Github.

@aaroncnc
Copy link
Author

aaroncnc commented Apr 18, 2021 •
edited

Okay, i am trying to wrap my head around the new config.
loadrt PRUencoder names=encoderJ0,encoderJ1 (here is where i declare how many encoders i have and the names? so in my case i have 1 encoder for each axis then 1 for spindle total 4. )

Remora Process Value (PV) feedbacks
net encoderJ0-count <= remora.PV.2 (this is what links the above mentioned encoders with the config file inside the SKR config correct?)

addf PRUencoder.capture-position servo-thread (this just load the encoder module)

Then i see in # Joint 0 setup
I see that this is where the link between the encoder and axis is setup. (a bit confused on how to link this to spindle vs axis)

And lastly i see in the ini file
[JOINT_0_ENCODER]
SCALE = 100 (this is for the Pulse per Rev?)

Sorry for alot of questions but i am a novice in Linuxcnc so i am learning as i go. But sometimes i feel the more i learn the less i know.

@aaroncnc
Copy link
Author

Did a bit more looking into the source, is the remora encoder module only giving the raw count?
And not the status of ch.a/b?

@scottalford75
Copy link
Owner

scottalford75 commented Apr 19, 2021 •
edited

The remora encoder module works the same way as the standard LinuxCNC encoder module but with the raw counts being performed in the controller board in firmware. Position and velocity are outputs.

Looking at the spindle documentation it looks like the scaled position feedback goes to spindle.N.revs and the velocity feedback to spindle.N.speed-in. This is how it is also shown in the above example.

Below is totally untested, but conceptually:

loadrt PRUencoder names=spindle-encoder

addf PRUencoder.capture-position servo-thread

setp spindle-encoder.position-scale "your scale value"

/# The spindle encoder position should be scaled such that spindle-revs increases by 1.0 for each rotation of the spindle in the clockwise (M3) direction.

net spindle-index <= remora.input.6 => spindle.0.index-enable
net encoder-count <= remora.PV.2 => spindle-encoder.raw_count
net spindle-postion <= spindle-encoder.position => spindle.0.revs
net spindle-speed <= spindle-encoder.veloctiy => spindle.0.speed-in

@aaroncnc
Copy link
Author

aaroncnc commented Apr 20, 2021 •
edited

How do i define a pin to be pulled high?
I was looking at main.cpp and see only 2 options for the pins, input and output. i was thinking maybe one could define Input_Pullup.
My encoder needs a,b,z pulled up.
For now i am just using a resistor but would be nice if this could be done via config file.

@aaroncnc
Copy link
Author

aaroncnc commented Apr 20, 2021 •
edited

The remora encoder module works the same way as the standard LinuxCNC encoder module but with the raw counts being performed in the controller board in firmware. Position and velocity are outputs.

Looking at the spindle documentation it looks like the scaled position feedback goes to spindle.N.revs and the velocity feedback to spindle.N.speed-in. This is how it is also shown in the above example.

Below is totally untested, but conceptually:

loadrt PRUencoder names=spindle-encoder

addf PRUencoder.capture-position servo-thread

setp spindle-encoder.position-scale "your scale value"

/# The spindle encoder position should be scaled such that spindle-revs increases by 1.0 for each rotation of the spindle in the clockwise (M3) direction.

net spindle-index <= remora.input.6 => spindle.0.index-enable
net encoder-count <= remora.PV.2 => spindle-encoder.raw_count
net spindle-postion <= spindle-encoder.position => spindle.0.revs
net spindle-speed <= spindle-encoder.veloctiy => spindle.0.speed-in

i get the error ./remora-xyz.hal:50: Pin 'spindle-encoder.veloctiy' does not exist

remora-xyz.txt

@scottalford75
Copy link
Owner

Hi, sorry for the typo. Spelling of velocity.

@aaroncnc
Copy link
Author

I can't belive I missed it.
Is there a way to define pull up on inputs?

@scottalford75
Copy link
Owner

That's been on the TO DO list. The underlying pin driver has the capability already but it not exposed in the Json configuration or DigitalPin module as yet.

@aaroncnc
Copy link
Author

aaroncnc commented Apr 21, 2021 •
edited

fixing the spelling now i get another error
./remora-xyz.hal:50: Pin 'spindle-encoder.velocity' was already linked to signal 'spindle-velocity

Also i had to comment out net spindle-index <= remora.input.6 #=> spindle.0.index-enable

I got this error
./remora-xyz.hal:55: Signal 'spindle-index' can not add I/O pin 'spindle.0.index-enable', it already has OUT pin 'remora.input.6'

@scottalford75
Copy link
Owner

Ok, my mistake. The standard linuxcnc encoder module and an index-enable IO as well that is meant to be connected to the spindle index-enable.

The PRUencoder component will need to have this functionality. Let me have a look.

BTW, I'm just testing the modifiers for inputs. Inverting, Open drain, pull up and pull down functionality now working on the test bench. I'll push the updates shortly.

@scottalford75
Copy link
Owner

New update pushed to the repo, both source and firmware.bin. Input modifier functionality.

In the Digital Pin Json config, modifiers are enabled by adding

"Modifier": "Pull Up",

Modifiers are: Invert, Open Drain, Pull Up, Pull Down, Pull None.

@aaroncnc
Copy link
Author

Awesome.

In my case the encoder needs a pull up on all logic pins. (currently being done via 3k resistors)
would it be possible in the future to add pull up to the encoder?

Would a work around for the spindle encoder just to tinker around with at the moment be to use the RPI gpio to linux cnc?

Any way for me to send you some beer money for all your hard work?

@scottalford75
Copy link
Owner

Hi, should be an easy feature to add to the encoder module. Let me have a look.

Thanks for the appreciation and offer. Beer money also helps buy components for testing etc to be able to keep adding features. My Paypal account is the same as my username @gmail.com

@scottalford75
Copy link
Owner

Ok, I reworked the output pin modifier options to be at a lower level. This allows the encoder module to use it.

I cannot test as I don't have an optical encoder. Can you test? Add the modifier to the encoder Json config:

"Modifier": "Pull Up",

Thanks

Scott

@aaroncnc
Copy link
Author

aaroncnc commented Apr 22, 2021 •
edited

Seems to be working ish but not sure.
When i have pull up enabled and remove my pull up resistors the system is only counting in one direction.
And in the serial logs i see that it has made both encoder pins as pull up. so at least i know its setting them in theory.
I put my MM on the pins and i get the following
Pull up = 2.3v
Pull down = 0v
Pull none = 2.3V
Its possible that the way this omron encoder is built it needs a external pull up resistor to get it up to 5V vs the internal 2.3v
(https://www.ia.omron.com/product/item/2469/)

Hmm it seems a 300ppr encoder may be too much. i have it connected to a 12V motor just to test and the spindle position counter seems to stop increase its count speed at a certain point as the motor goes faster. but without index working i dont know how many rpm it is.

@scottalford75
Copy link
Owner

If it's only counting in one direction then is probably missing the A or B channel. The logic is designed to cope with a missed pulse and will count up by two on one channel.

The encoder module runs at 40khz so will have a limit. The QEI module is probably the ultimate solution and needed feature for high speed counting.

@aaroncnc
Copy link
Author

Okay that makes sense.
The external resistors will stay for this encoder but i may try another one.
So with they way linux cnc is currently setup without reworking the encoder module there is no way to get index running?

@scottalford75
Copy link
Owner

Hi aaroncnc,

I have added index functionality to the Remora encoder module and the PRUencoder component. Tested on the benchtop with a magnetic encoder.

The encoder module will output the index position count for one SERVO_PERIOD along with the index pulse.

In your HAL file you will need to

  1. net the encoder.index-enable to the spindle-index-enable
  2. net the remora.input.i (as per Json config) to the encoder.phase-Z

The Json config now has the ability to pass the index pin details, the physical pin and the input data bit.

   {
"Thread": "Base",
"Type": "Encoder",
	"Comment":			"Motor encoder for Joint 0",
	"PV[i]":			        2,
	"ChA Pin":			"1.20",
	"ChB Pin":			"1.22",
	"Index Pin":			"1.18",
	"Data Bit":			7
},

@aaroncnc
Copy link
Author

I am havving issues installing the new PRUencoder
When i run: Sudo halcompile --install PRUencoder.c
I get an error
In function export_encoder
265.2 phase undeclared
265.8 z undeclared

looking at the code was this to be a comment?
If so i changed 265 to /* phase-Z */
After doing that it installed.

@scottalford75
Copy link
Owner

scottalford75 commented Apr 25, 2021 via email

@aaroncnc
Copy link
Author

Should i wait to flash the board?

@scottalford75
Copy link
Owner

scottalford75 commented Apr 25, 2021 via email

@aaroncnc
Copy link
Author

aaroncnc commented Apr 25, 2021 •
edited

Any chance you can post the snip of the hal file for the encoder?

@scottalford75
Copy link
Owner

scottalford75 commented Apr 25, 2021 •
edited

I was using it on an axis and tested homing on index. I don't have a spindle but the following might work.

net encoder-count <= remora.PV.2 => spindle-encoder.raw_count
net encoder-phaseZ <= remora.input.6 => spindle-encoder.phase-Z
net spindle-index <= spindle-encoder.index-enable => spindle.0.index-enable
net spindle-postion <= spindle-encoder.position => spindle.0.revs
net spindle-speed <= spindle-encoder.veloctiy => spindle.0.speed-in

@aaroncnc
Copy link
Author

How would one see if the pulse is working in the show hal configuration?
i noticed in the above it looks as if one would want to watch remora.input.6
I am a bit confused between the link from setting the config on the skr in the encoder section to the hal file.

@scottalford75
Copy link
Owner

Ok, for the config, that data bit is the remora.input."Data Bit" in your HAL config. Index Pin is the SKR pin your using for the Phase Z index.

"Index Pin":			"1.18", 
"Data Bit":			7

For testing, you will either need to use halscope or use halshow to monitor the spindle-encoder.index-enable pin. The pulse is short so you will not see it when watching remora.input.i

setp spindle-encode.index-enable

and then watch this pin. It will go from high to low when the index pulse is detected.

@aaroncnc
Copy link
Author

Okay that makes sense.
I was a bit confused as i was used to the inputs being there own thing.
This raises one more question tho.
if one were to have an encoder on each axis plus spindle thats 4 inputs taken possibly 5 is you have a rotary axis.

@aaroncnc
Copy link
Author

20210425_113556
I also set "setp spindle-encoder.index-enable 1"
Okay so i did some testing and i can see the pulse on input7 and spindle phase Z but the index enable is always at 0

@scottalford75
Copy link
Owner

Okay that makes sense.
I was a bit confused as i was used to the inputs being there own thing.
This raises one more question tho.
if one were to have an encoder on each axis plus spindle thats 4 inputs taken possibly 5 is you have a rotary axis.

Yes, having anther 8 inputs would be handy. There is room in the data packet, would just need to rework the code to be able to pack and decode two 8 bit bytes.

@scottalford75
Copy link
Owner

scottalford75 commented Apr 25, 2021 •
edited

20210425_113556
I also set "setp spindle-encoder.index-enable 1"
Okay so i did some testing and i can see the pulse on input7 and spindle phase Z but the index enable is always at 0

I've learnt something more about LinuxCNC when working on the index capabilities and what is meant by an index. The index is the position at which the encoder is zero'd.

So the index-enable input (and output) is a notification to the encoder to reset its internal position count to zero when it next have a phase Z input. And when you do that tell LinuxCNC that you have by resetting the index-enable input to low. The encoder will never set the index-enable high.

image

@scottalford75
Copy link
Owner

So, for your spindle set-up. LinuxCNC at some point (spindle homing??) will request the encoder to index-enable to set the position to zero on the index pulse. I haven't looked into how the spindle does this or when.

@aaroncnc
Copy link
Author

aaroncnc commented Apr 25, 2021 •
edited

Also was doing some reading and am thinking that maybe my calculation for max encoder was off.
when looking at other people configs i stumbled across this

# 500ppr encoder on spindle 
# INPUT_SCALE=500 ppr x4 (quad) = 2000 ppr
# 2000/360=5.555* p/degree

so it may be
3000(max spindle speed)*300(pulse per rev) * 4(for quadrature) /60(seconds) = 60,000 / 60KHz

So maybe an encoder sub 100 ppr
3000(max spindle speed)*60(pulse per rev) * 4(for quadrature) /60(seconds) = 12,000 / 12KHz

This may explain why even at what i thought was lower speeds i was losing counts...
I should ask on the forum what the right way to calculate the bandwidth is.

@aaroncnc
Copy link
Author

aaroncnc commented Apr 26, 2021 •
edited

Okay so i tested again and you are correct it is enabled as i have it set in my hal and then once the pulse comes it turns off.
I also was able to do a quick test of the spindle sync with

G90 (set absolute mode)
G0 X1.000 Y1.000 Z0.100 (rapid move to starting position)
S100 M3 (turn on the spindle, 100 RPM)
G33.1 Z-10.0 K0.05 (rigid tap a 20 TPI thread 10.0 deep)
M2 (end program)

I have the system on my bench with a small motor that i can move with my hand and it works. Z axis is moving in step with the spindle.
BUT
There is an issue that once it reaches the bottom of the hole the system sets the DAC value negative to go in reverse and then nothing happens.

I have also noticed that spindle encoder position and spindle position always counts up no matter what way i spin the encoder.
TBH im not sure what is correct more of a note.

I was also testing out http://linuxcnc.org/docs/html/gcode/m-code.html#mcode:m19
and not having any luck.

@scottalford75
Copy link
Owner

Makes sense as the PWM value goes negative for reverse. What we'll need is a direction output for the VSD which is driven by the sign of the PWM value.

Does your VSD have a direction pin available?

Good to hear the encoder side of things is working!

@aaroncnc
Copy link
Author

aaroncnc commented Apr 26, 2021 •
edited

So my vfd is setup such that when feed 0-10v it goes counter clockwise. And when a pin is pulled high it goes clockwise. I have this in my Hal file but the dav value still goes negative despite there being a direction pin.

Also is the encoder/ spindle position always to count up no matter what way it's spun?

Is there a way to see more info to try to find out if the module is dropping pulses from the a/b channels.

@scottalford75
Copy link
Owner

Ok, firstly something wrong with the encode if it's only counting up. One of the channels is not connected correctly.

The Remora PWM module currently can only handle a positive value.

Can you please share your HAL files?

@aaroncnc
Copy link
Author

one of the resistor came off my encoder, this has been fixed and it is working.
I am able to do a full rigid tap cycle in both directions.
I also fixed the negative value for DAC
with the following
loadrt abs count =1
addf abs.0 servo-thread
net spindle-speed-abs scale.0.out => abs.0.in
net spindle-speed-DAC abs.0.out => remora.sp.3

@aaroncnc
Copy link
Author

aaroncnc commented Apr 27, 2021 •
edited

Question.
What would the best way to control the spindle speed via PID loop
I have been thinking about this and can think of 2 options

  1. setup in hal and link it to the DAC output going to the skr1.4 pwm pin
  2. have the PID done on the skr1.4 in a way like the temp control. something along the lines of a spindle module.

Im not sure one has an advantage over the other performance wise.
Time wise i am sure using HAL would be fastest as there is no need for code changes / additional work for little gain.

Still finding myself losing count at not that high of speeds with my 300ppr.
So in my testing once speed-in about 28 RPS (1680RPM) is the max

asked around and got sent a link that has this info https://www.forum.linuxcnc.org/38-general-linuxcnc-questions/34569-lathe-spindle-encoder-with-cheap-max-50-lpt-breakeout-board

The encoder frequency (count rate)
is the encoder counts per turn time the turns per second (RPM/60). In addition the base thread has jitter and the encoder signals will not be perfectly timed so you really want the maximum encoder count frequency to be about 1/3 of the base thread frequency

This would work out to 13.33KHz safe max
So if i am right in my math
1680(spindle speed)*300(pulse per rev) * 4(for quadrature) /60(seconds) = 33,600 / 33.6KHz
So with the current setup i think the max spindle encoder PPR and trying to keep below 14KHz for buffer
3k spindle speed => 70PPR
5k spindle speed => 40PPR
10k spindle speed => 20PPR (this may be to slow for spindle sync)

@aaroncnc
Copy link
Author

aaroncnc commented Apr 27, 2021 •
edited

Here is a mbed lpc1768 module
https://os.mbed.com/users/hexley/code/QEI_hw/docs/tip/

Spec sheet page 554
https://www.nxp.com/docs/en/user-guide/UM10360.pdf

@scottalford75
Copy link
Owner

Hi, great to hear things are working and well done with the HAL config. And thanks for finding the Mbed QEI code. That will make things so much quicker to integrate into Remora. A simple wrapper should be easy to code.

@scottalford75
Copy link
Owner

For your spindle PID I would use the LinuxCNC PID component. For 3D printer heater control I use PID on the LinuxCNC side.

@aaroncnc
Copy link
Author

aaroncnc commented May 5, 2021

I got pid working on my system.
But i am unable to tune it.
Once the system hits over 1600rpm and remora cant keep up with the encoder it sends the pid loop into overdrive.
Thinking of ordering another encoder of around 40-50 pulse per rev.
But i like the idea of more resolution from the 300ppr.

@scottalford75
Copy link
Owner

scottalford75 commented May 9, 2021 •
edited

Hi aaroncnc,

I've developed and added the QEI module into Remora. Ready for testing. In the Remora config.txt the module is enabled with

{
"Thread": "Servo",
"Type": "QEI",
	"Comment":			"QEI interface",
	"PV[i]":			2,
	"Enable Index":			"true",
	"Data Bit":			7
},

Of course the PV[i] and Data Bit settings are as per your specific configuration.

This should hopefully allow you to use your current encoder for higher speeds on your spindle.

@aaroncnc
Copy link
Author

aaroncnc commented May 9, 2021

Awesome. I will see if I can start testing tomorrow or Monday.

Side note I was looking into the chip and it's features and saw the dac but found on the skr1.4 the pos ref pin is not broken out but tied into the 3v line. Was thinking how awesome it would have been if it was broken out to a pad. Then a user could feed it a vref from a vfd and have another easy control option. But the only way to use it on a skr1.4 board would be to lift the leg of the pin and solder some fine coil wire.

On a plus side my vfd has a pdm input so no need to mess with a pwm filters as a simple dac. Thus will make the pid control much better

@aaroncnc
Copy link
Author

aaroncnc commented May 9, 2021 •
edited

It's working. Tested to over 10k rpm

@scottalford75
Copy link
Owner

scottalford75 commented May 9, 2021 via email

@aaroncnc
Copy link
Author

aaroncnc commented May 9, 2021

Yup I forgot I moved the pins off the dedicated ones.
This is so great to have the ability to read the spindle past 10k.
If I ever upgrade my bearings, new motors and add in oil coolant for them.
it's great to know this can handle it.

Question.
For the software encoders being used for the xyz the max pulse per Rev would be the say 14-20khz total
So per axis would be 4-6khz roughly.
This would give good headroom.
Granted you would need a beast of a servo to push that.
Right?

@aaroncnc aaroncnc mentioned this issue Sep 27, 2023
Closed
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
None yet
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
2 participants
@scottalford75 @aaroncnc