LCD 16x2- C code in 16f877a

[mizusuki]

Hi everyone, i'm new in C programming. I wrote a simple code in c for HD44780, using 4 bit mode, but it don't work!

Adress.h have some resgister's adresses to use.
Delay.h only have some delays.
I am not using RW, in the schematics this pin is connected to ground.
The code compiles, but nothing occurs on Proteus.
Can anyone help me?

[Ttelmah]

Well done for actually having a try!.

There is a supplied LCD driver with the compiler, and also the flex one in the code library which should both be studied.

However the instruction the _will_ be causing you grief, is using swap directly on the port.

Swap directly swaps the nibbles of a register. Quickly and efficiently. However 'PORTB' is _not_ a simple register. It's actually two registers in one. When you write to PORTB, the value is latched and fed out the pins, When you read from PORTB, you directly read the logic levels on the pins. This is why you can get the 'RMW' problem on the PIC (Read Modify Write). Where comes _back_ from a read, is not what you actually output.

Using Swap like this, the data you want to put out on the port, will will also result in RS, E, and RW being operated.....
Part of the data will also be lost, since what you 'read back', may not be the bit patterns you have output... :(

Separately, Your fuses and clock statement, _must_ be before you load any code. You don't show a clock statement, but have your fuses below loading Adress & Delays.

[temtronic]

couple of comments..
1) rename Init() to perhaps LCD_Module_Init(). Although it's obvious in this program Init() is for an LCD, in more complex programs 'Init()' could be fore any number of peripherals. Doing this allow your code to be 'selfcommenting' so you(and others) _know_ what is happening. Also I'd rename any function that the LCD uses to 'LCD_purpose', again to make it easy to see what the function is for.

2) Put a delay_ms(500) before your program runs LCD_Module_Init(). Every LCD Module requires a 'long' hardware setup time, 2-300 ms is typical. It needs this time to internally configure itself to it's defaults. The PIC is super fast in comparison, so without the delay the PIC will try to access the LCD when it's not properly setup.

3) Be aware that Proteus is full of bugs, errors and faulty RDCs! The only real 'simulation' that will show what's happening is the Real World. It's always best to try code in a real PIC even in a simple white 'breadboard'. Heck if it works on one of them it WILL work in a PCB !

Jay

[RF_Developer]