Driving a 2x16 LCD with only One Pin and 74HC595

[struppi81]

Now im confused

LCD_Init _Only the First 4 Commands (2 Steps):

Step1: shiftout 1 byte.
Enable_High + Data high nibble + Latch => nearly 910µs (Delay at the next Command)

Step2: shiftout 1 byte
Enable_Low + Data high nibble + Latch => nearly 910µs (Delay at the next Command till Latch)

=> 1,8 µs => extra delay necessary.

Next Command....

The 3 others Commands 4 Steps ; (see after LCD Init)


After LCD Init (4 Steps): (Commands without RS)

Step1: shiftout 1 byte.
RS + Enable_High + Data high nibble + Latch => nearly 910µs (Delay at the next Command or Data)

Step2: shiftout 1 byte
RS + Enable_Low + Data high nibble + Latch => nearly 910µs (Delay at the next Command or Data)

Step3: shiftout 1 byte
RS + Enable_High + Data low nibble + Latch => nearly 910µs (Delay at the next Command or Data)

Step4: shiftout 1 byte
RS + Enable_Low + Data low nibble + Latch => nearly 910µs (Delay at the next Command or Data till Latch)

=> 3,6µs

Next Command or Data....

[Darrel Taylor]

Or I'm confused, not sure.
I see how it takes 4 "steps" just to toggle the E line.

But, the LCD will not accept any data or commands while it is busy.
Even though it takes 4 steps ... you are clocking in the first nibble after the first 2 steps 1.82 mS.

The HD44780 datasheet timing diagrams show that the first nibble can't be clocked in until after the last command is complete (not busy).
There is no text that confirms it, but that's what the timing diagrams show.