I have been comparing the required timing for the vfd on pg 16 of it's datasheet, with that for the uno on the atmega datasheet, pg104 which deals with the timer counter and the output compare registers.
Why?
Also using the simpler diagram in the textbook which compares the data signals with the signals on the en, r/w, r/s pins, just like for the vfd timing diagram.
That is where at least one error is. Here is a relevant part of your code, properly displayed in the forum post using the 'code' button.
//*******************************************************
void lcdCommand( unsigned char cmnd )
{
LCD_DPRT = cmnd;
LCD_CPRT &= ~ (1<<LCD_RS); // LCD_RS pin of PortB is cleared.
LCD_CPRT &= ~ (1<<LCD_RW); // LCD_RW pin of PortB is cleared.
LCD_CPRT |= (1<<LCD_EN); // LCD_EN pin of PortB is set.
delay_us(1);
LCD_CPRT &= ~ (1<<LCD_EN); // LCD_EN pin of PortB is cleared.
delay_us(100);
}
//*******************************************************
I see that you have added some comments, but they really are not appropriate. Anyone who is reading your code, even an assembly language person like me, can tell that your second line of code clears the LCD_RS pin. Your comment is telling what is being done whereas it really should be telling why it is being done. In other words the comment should tell why the bit is being cleared.
You have left out three comments and the two relating to the delays are quite important. Take a look at those delays and compare them to the timing diagram. Then take another look at the timing diagram and see which of the delays on that diagram is not being implemented.
It would also be appropriate to include a generalized comment at the top which explains what the function as a whole does.
I'm also keeping in mind my ultimate objective which is for the program to sense signals for various parameters (altitude, airspeed,airpressure,mach,...) and display any 3 on the first 3 rows of the display, with the 4th used to enter new information, which is automatically sent to row 1 with previous information 'stepping down' to rows 2 and 3, row 4 remaining void for new info.
Let's just get 'Hello World' working first. After you get that working the rest will be simple.
Where is the circuit diagram?
Don