I connected STM32 F334R8 microcontroller to L298 H-bridge. I made some measurements. The problem is output signal on L298 has quite slow slopes and is not as sharp as input signal. I do not understand why the distortion occurs. As you can see the frequency is very low - only 10 Hz.
Pink color = L298 output signal,
Yellow color = L298's Enable pin (STM32's PWM output),
Green color = L298's Input 1 (STM32's output),
Blue color = L298's Input 2 (STM32's output),
Input 1 and Input 2 determine direction of output current.
Note 1: Oscilloscope waveform acquire is in Hi-Res to average signals.
Note 2: On PWM output (yellow) I am generating abs(stepped_sin(x)). Then to make stepped_sin() on the L298 output I am changing Input 1 and Input 2 (just inverting current direction).
I'm just curious what's the reason of such strange behavior.
L298 logic supply voltage is 5 V, power supply voltage is 8 V. Output load is 4Ω power resistor.
I have already checked L298 datasheet and typical PWM switching frequency is 25 kHz. Also input's logical high starts with 2.3 V. My microcontroller uses 3.3 V logic so it should be sufficient, isn't it?