pic16f690 serial communication c code examples

We are done with the theory part now, In the next section we will take a look at the programming microcontroller to control LCD in 4-bit mode.Introduction to the Microchip PIC C Programming Decemby rwb, under Microcontroller. This means in both command and data sending function we need to saperate the higher 4-bits and lower 4-bits.

As i already explained in 4-bit mode data is sent nibble by nibble, first we send higher nibble and then lower nibble. LCD connections in 4-bit ModeWe will now look into the common steps to send data/command to LCD when working in 4-bit mode. Potentiometer RV1 is used to control the LCD contrast. then you may connect it on your controller but that will only increase another pin and does not make any big difference.

We are not using Read/Write (RW) Pin of the LCD, as we are only writing on the LCD so we have made it grounded permanently. D4-D7 are the data pins connection and Enable and Register select are for LCD control pins. For me about 400uS works perfect.Ībove is the connection diagram of LCD in 4-bit mode, where we only need 6 pins to interface an LCD. So if you feel any problem running the LCD, simply try to increase the delay. So it actually depends on the LCD module you are using. This delay might vary depending on the LCD you are using, as you might have a different crystal frequency on which LCD controller is running. Instead we simply put a certain ammount of delay usually 300 to 600uS. Usually we do not use busy flag in 4-bit mode as we have to write code for reading two nibbles from the LCD. The busy flag will only be valid after the above reset sequence.

Select bus width (0x30 - for 8-bit and 0x20 for 4-bit).

We call this special sequence as resetting the LCD. To enable the 4-bit mode of LCD, we need to follow special sequence of initialization that tells the LCD controller that user has selected 4-bit mode of operation. In 4-bit mode the data is sent in nibbles, first we send the higher nibble and then the lower nibble. One basic reason is lesser number of pins are needed to interface LCD. There are many reasons why sometime we prefer to use LCD in 4-bit mode instead of 8-bit.

Now we are going to learn how to use LCD in 4-bit mode. Introduction to 4-bit ModeTill now whatever we discussed in the previous part of ths LCD tutorial, we were dealing with 8-bit mode.

Pic16f690 serial communication c code examples