Right now there is a memory leak present because the allocated memory is not freed in the object destructor.

I am up to use this IC for a PWM. Do I have to use exact pins? Or I can use any of the digitals from UNO?

Just a few quick thoughts:

• Multi statement macros (e.g. ShiftRegisterPWM_toggleClockPinTwice) should be written using do{"statements"}while(0).
• Consider calloc in the ShiftRegisterPWM to allocate and clear the memory at the same time, this avoids two nested loops.
• Also floating point calculation (slow and long) code “value = (uint8_t) (value / 255.0 * resolution + .5)” can be avoided by something like “value = (uint8_t)( ( (uint_16)value * resolution + 127 ) / 255 )”.
• I think one dimensional array (just to store channel values) is enough for this task as the actual output value is very easy to “compute” in the interrupt by comparing actual time variable to resolution variable. Sure it would be slower compared to the using the precomputed values at the large array.
• A believe 74595 can be effectively fed by SPI.

I made a connection to D1, D2, D9.is it OK? can I use it for PWM output ? I'il use it for DC motor ENA.

Hi @Simsso, this library is excellent and very easy to use. Very well documented on your blog too. May I ask if it is safe to use with the ESP32 dev module? Can it work theoretically with some modifications and adaptions, or it will damage something?

Thanks.