Stuck with spindle interface 7i76 card and weird BLDC driver

Hello,

I tried to figure that out, but not really successful, so I spam the forum with the questions. (I have the feeling I should have found the information somewhere; maybe someone can point me in the right direction) 
I have a 6i25 card with a 7i76 card connected to my PC. Some stepper motors are running and can be moved with keyboard, a basic configuration is running.

Now I got stuck, trying to hook up the old BLDC driver (labeled TONMAN Brushless DC driver) or the machine (which I have no documentation for) seems not to run with an analog input. 
I tried to connect the Spindle interface somehow, but it does not want to run.

There is a pair of pins labeled +- (PWM / ANNA), but I think it is not really for analog input signal.
Hooking up a potentiometer (allowing to create a voltage between 0 and 5V) does nothing to a certain voltage. At approx. 2.6V it switches from "off" to "full speed".
I tried one of those PWM generators   which works fine. It allows to control the speed of the motor, no issue. I can adjust the motor speed by setting the duty cycle to anything between 10% and 100% and it seems to be what I need. 

Now the questions: Is it correct that in my situation the spindle interface of the 7i76 is just the wrong choice for my BLDC amplifier?
                                How do I make a PWM control for my spindle with the 7i76 (6i25)?
                               
Greetings Timo



 

Yeah, sounds like it's a 5V PWM input.
 
There is 5I25 +7I76 firmware that replaces one stepgen (stepgen4)
with a PWMGen:

 

Which should work to drive the motor driver

Thank you for reply.

So to change the firmware rather than using the software PWM is the way to go?
linuxcnc.org/docs/html/man/man9/pwmgen.9.html

I will give the the firmware change a try.

I hope I will not "brick" the card.

I used sudo mesaflash --device 5i25 --write 5i25_7i76x2_1pd.bit --reload

Now I cannot get the direction change working. Is the direction pin of the stepgen still working?
I am using TB3 Pin2 und Pin3 for the PWM.
I tried to find a direction pin.

I can switch the spindle on and off via Axis UI and can also change speeds. (but not the directions)

The direction pin is  GPIO (GPIO8)

So you need to set gpio8's is_output parameter
and link it to the spindle direction pin.

 

Thanks for looking into things.
I am not sure if I understand correct.
If I type mesaflash --device 5i25 --readhmid I get this



Is I/O port and GPIO refering to the same thing. In the screenshot I/O port 8 says it has no sec. (secondary?) function.


 

All pins have GPIO capability (primary function) 
Secondary functions are PWM,Stepgen etc

I do not really understand. If I flash another bit file (obviously it has two pwm gen) it shows four lines. (that is not a fix, because I wanted to use a stepgen on pin4 and Pin17)

        IOPortTag & x"00" & PWMTag & PWMBDirPin,                 -- I/O 06    PIN 4
        IOPortTag & x"00" & PWMTag & PWMAOutPin,                -- I/O 07    PIN 17
        IOPortTag & x"01" & PWMTag & PWMBDirPin,                 -- I/O 08    PIN 5
        IOPortTag & x"01" & PWMTag & PWMAOutPin,                -- I/O 09    PIN 6

The version with one PMW shows only one line. One line seems to be "empty". 

        IOPortTag & x"00" & NullTag & NullPin,                              -- I/O 08    PIN 5
        IOPortTag & x"00" & PWMTag & PWMAOutPin,                 -- I/O 09    PIN 6

Is there something missing? I would have expected something like:

        IOPortTag & x"00" & PWMTag & PWMBDirPin,                 -- I/O 08    PIN 5
        IOPortTag & x"00" & PWMTag & PWMAOutPin,                -- I/O 09    PIN 6


Greetings Timo

p.s. Do I understand it right that the gpio.008 is not predefined connected for this pwmgen, but could have been used for something else as well?
I am still curious if the tags in the firmware would change anything in terms of use.

Now I put folllowing lines in the .hal (particular unsecure if the setp is what is to be done)

setp hm2_5i25.0.gpio.008.is_output 1
net spindle-ccw spindle.0.reverse => hm2_5i25.0.gpio.008.out

That switches the polarity on the TB3 pin4 and TB3 pin5, that again changes the direction of the motor.

Do not fully understand why it does not switch between 0 and 4.9V. It switches between -4.9V and 4.9V.
 

The outputs on TB3 pin 4 and 5 should be used individually,
 that is, you would use the appropriate output and
GND (TB3 pin 1) NOT both outputs to create a 5V signal
Which output you chose depends on the direction polarity.

On later bitfiles I have changed from PWMDIR to GPIO
on some configurations because it is more flexible
(many systems do not use the DIR pin and it is unavailable
as a general purpose output in these cases)

And yes, GPIO8 can be used for any type of output.
 

Thank you. That clears things up a little more.

So I can change the wiring a bit, Maybe even connect the other pin to the drive enable.