I have 3 concerns.
Which of the 4 that you have listed is not a concern?
(1)
I looked at the timing diagram ...
What timing diagram are you referring to. You haven't posted a link to the data sheet that you are using. If it is the same as mine you should be looking at Figure 10.3 on page 16.
...compared it to the lcdCommand routine.
What lcdCommand routine are you referring to?
Data is sent on the high-to-low enable signal AND when the register select and RW signals are low.
Not quite correct. Data is sent to the LCD module under these conditions. The register select then determines whether the data goes to the instruction register or to the data register.
Seems to be related to the time for an instruction to be run as shown in the table of page 3 of the data sheet;
No. The instruction time on page 3 is the time that you must wait after you have sent one instruction to the LCD and before you send the next one. We are talking about the timing between the various signals that you send to the LCD in the process of generating an instruction.
(2) and (3)
Since you have your delays confused I don't think I can attempt to answer these yet.
[Edit]: Don't forget that the author (who probably didn't write the code himself) was dealing with an LCD and not a VFD. You would have to compare the delays that he used with the data sheet for the device that he used.
(4)
When you get the ...getsync(): not in sync: ... error there is usually a communications failure between your computer and your Arduino.
Take another look at reply #14, specifically this part:
Now compare this to the timing diagram in the data sheet (NOT in the textbook) and find out what is missing and/or wrong.
Post your corrected code and we will proceed from there but do not send any more code in PDFs. Post the code as part of your forum entry as I did in reply #14.
Don