editing LCD.c driver

[Markdem]

Hi All, I know that this could be done with the flex driver, but i would still like to know what the following two line mean in the ccs lcd.c driver

#byte lcd = 0xF81 (when using port b)

and

#byte lcd = 6 (when using port b)

I had a look in the datasheets, thinking it was a memory location, but the location on the datasheet for port b is 0xf85.

Could sombody please tell me what he two line do.

Thanks, Mark

[treitmey]

for lack of a better term, they "overlay" the variable created((lcd)) on top
of a memory location.
But these locations are special in that they are i/o ports.

The pins will still need the tris set properly,

but after that if you can say
lcd=0b01000100; //that is how the pin will be set.

and the same goes for reading.
int8 my_new_var;
my_new_var=lcd;//this reads the values on the pins.


ALSO keep in mind that different chips have the ports in different mem locations.
ie look at 18F452 spec page 47(45)

[Ttelmah]

Question. Which data sheet has portb, at F85?. It is F81, on all the '18' chips I have used. 0xF85, is normally portf....
Double check the sheet.
The '6' location, is for '16' chips which have the ports mapped at the bottom of memory, instead of the top.

Best Wishes

[Markdem]

Thanks for that guys.

So my asamption was almost right. I did not see that the code is checking to see if I am using a 16F or 18F chip.
I should of said that ia am planing on using a 16F690, so i will need to use "#byte LCD = 7" if i want to use PORTC.

Ttelmah, you are right, 0xF85 is the TRISC location on the 16 chips, I just did not understand what the code was doing.

One more question, i checked that CCS help file, but still dont quite understand what #byte does. Is it just like declaring a veriable and then settting a vlaue for it?

Thanks, Mark

[treitmey]

Read my above reply.

What is read from the variable is the voltage level of the pins.


What is written to the variable is voltage set on pins.
that is 0 or 5V


but you need to set the tris