Stuttering with L298N H-Bridge about control-surface-motor-fader HOT 4 CLOSED

PWM input is supported on both the input pin and the enable/inhibit pin. However, the behavior is different, because the freewheeling current takes a different path. See page 4 and figure 7 of https://www.st.com/resource/en/application_note/cd00003776-applications-of-monolithic-bridge-drivers-stmicroelectronics.pdf for more details.
I've never really compared the behaviors of both modes, so I can't really tell you whether this is the cause of the issues you're facing.

That said, you shouldn't need to modify too much if you want to switch to a 3-pin drive mode.
What you need to know about the timers is that they generate a rectangular PWM wave on an output pin, the duty cycle of which is set by the value in the Output Compare register (OCRnX, where n is the timer number, and X is the channel, either A or B). The code uses two timers (Timer 0 and Timer 2), and each timer has two channels, A and B. Each channel is hard-wired to a specific pin, e.g. Timer 0 channel A drives pin 6. You can see this on page two of the full pinout: pin D6 is labeled OC0A (Output Compare of Timer 0, channel A).
Besides OCRnX, another important register bit is the COMnX0 bit (Compare Output Mode for timer n channel X) in the TCCRnA register (Timer/Counter n Control Register A). When set to 1, this bit inverts the output pin. Toggling this bit has the effect of changing the duty cycle to its complement, e.g. from 25% to 75%.
As you probably know, to change the direction of the motor, you need to invert both input pins, i.e.

The current code does the following to change direction: it inverts the output pin of IN2, and it changes the COMnX0 bit for the IN1 pin. This is done here for forward and backward operation, respectively:

To change this to 3-pin operation, you can do the following. Let's assume the following pinout, and we'll only look at one fader:

To initialize (Motors::begin()), we just set all three pins as outputs:

    if (Config::num_faders > 0) {
        sbi(DDRD, 2); // PD2 output
        sbi(DDRD, 3); // PD3/OC2B output
        sbi(DDRD, 4); // PD4 output
    }

To move in one direction (Motor::forward()):

    else if (Idx == 0)
        ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
            cbi(PORTD, 2); // IN1 low
            sbi(PORTD, 4); // IN2 high
            OCR2B = speed;
        }

And to move in the other (Motor::backward()):

    else if (Idx == 0)
        ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
            sbi(PORTD, 2); // IN1 high
            cbi(PORTD, 4); // IN2 low
            OCR2B = speed;
        }

Note that the COM2B0 bit is no longer used, it is always set to zero, regardless of direction.

from control-surface-motor-fader.

Success!!! It's buttery smooth now, apparently, the L298N should only receive pwm signals on it's ENA pin..
The code you provided worked on first try! Really a simple change, thanks to your great design :)
Thank you so much 😊

from control-surface-motor-fader.

Wow! Thanks so much for the detailed answer! I'll see to trying this out as soon as I can!
In the meantime, I'll also order some L293Ds, just in case.. they are truly cheap :D
Thanks again, I'll report back when I get some results 👍

from control-surface-motor-fader.

The L293Ds arrived, got an even smoother operation with them. I recommend any future readers to just use these.

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