Hi John. I just posted below the further explanation. In short the PWM signal does need to be at 100hz. The docs I saw for digitalwrite are around 490hz. So I think the direct command was either a timing choice or a user method that worked for Uno vs the digitalwrite. But that’s why I was inquiring to try to understand why that might have been chosen as again I haven’t used that before. So this is new to me. And if I were to change it and try it, I wouldn’t have known why it may or may not function. So just trying to educate myself and possibly learn new techniques for the future. Open to better approaches or something I may not know in handling the frequency to 100hz.