Firstly, I am not at all competent enough to do what I want, but am going to attempt anyway.
I am in need of a tachometer for my 1980 Land Rover Series III diesel. Since there are more than enough inputs, I had the idea to also put a water temp and oil pressure sensor into the mix. So, one Arduino, oil, tep and RPM sensors and three HD44780's (and maybe a feedback loop to send alarm on high temp/low pressure).
It looks to me, after researching, that I can do at least two of these, and possibly all in 4 bit mode and a three wire configuration with separate LCDs (two or three screens to a board). But, I notice in all the different ways to connect the LCD, that they all use at least two of the PWM pins.
So, my question is, does the LCD communicate using PWM (pins 9,10,11) or, can I use any I/O pin for comms? Is this just coincidence that the schematics all use two PWM pins? If the HD44780 needs one or no PWM pin, I think I can get three screens on a board?
Does that make sense?