Hi all i have a question about a code

This is part of the code, it write to LCD.
Hitachi HD44780. It uses it in 4 bit mode

PORTB bits 0-3 are connected to the LCD data bits 4-7 (high nibble)

Code:

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lcd_putch(char c)
{
        LCD_RS = 1;        // write characters
        PORTB = (PORTB & 0xF0) |  (c >> 4);
        LCD_STROBE;
        PORTB = (PORTB & 0xF0) |  (c & 0x0F);
        LCD_STROBE;
        DelayUs(40);
}

---

I cannot understand the next rows:

PORTB = (PORTB & 0xF0) | (c >> 4);
PORTB = (PORTB & 0xF0) | (c & 0x0F);

What about them can't you understand?

> PORTB & 0xF0
Preserves the top 4 bits, and clears the bottom 4 bits.

The two operations on c get the top 4 bits and bottom 4 bits into position read to add (using |) to the existing portb value.

What role is this expression do: (c >> 4)

Easily answered by looking in a book.

It shifts the bits in c to the right by 4 places.

So if c looked like:

10100000

It would now look like:

00001010

Quote:

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Originally Posted by DavidP

It shifts the bits in c to the right by 4 places.

So if c looked like:

10100000

It would now look like:

00001010

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and c better be unsigned char for this