3144 Hall Switch Tachometer Code: Getting RPM in smaller intervals than 60?

FWIW , my understanding is AVOID printing in the magnet_detect ISR as you intro delays.
// lcd.setCursor(0,0);
// lcd.print("detect");

avoid it, or it won't work at all?

How can I get the rpm calculation to print on my i2c?

It's not that I don't understand calculating frequency from period, just an arduino noob. Need help w coding.

Can you get anything on the LCD? The Setting up bit for example.

Your lcd declaration looks odd. With an I2C version, I wouldn't expect anything more than address, columns and rows. What are all those other numbers? Can you get a library example to show some text?

I agree it’s odd. But it’s the one thing that’s consistently worked to display things on my display. I’ll try just (0x27,16,2) at the declaration and see what happens.

Yes I and the original code worked with that declaration it all the numbers. Display bars and everything.