PIC to LCD interface

This article here is about how to interface PIC with LCD. Here in this project I am using PIC 16F84A and HD44780 compatible LCD. Though any character and line LCD can be used as long as it has HD44780 based controller, with minor software changes (see LINE2 routine in code), I used 16x2 line LCD. LCD can be interfaced both in 8 bit and 4 bit mode. I am using 4 bit interface mode so Port A and bit 0 of port B of PIC are free for any use. Let’s start with schematic. See the table for complete connection details.

LCD connection details
LCD Pin no.	Description	Connected to
1	Vss	0v
2	Vdd	5v
3	VO Contrast adjust	Potential divider
4	RS Register Select	RB1(Port-B Bit-1) of PIC (Pin 7 of PIC)
5	R/W Read/Write	RB2 of PIC(Pin 8)
6	E Enable	RB3 (Pin 9)
7	DB0 Data Bit 0	Not used
8	DB1 Data Bit 1	Not used
9	DB2 Data Bit 2	Not used
10	DB3 Data Bit 3	Not used
11	DB4 Data Bit 4	RB4 (Pin 10)
12	DB5 Data Bit 5	RB5 (Pin 11)
13	DB6 Data Bit 6	RB6 (Pin 12)
14	DB7 Data Bit 7	RB7 (Pin 13)
15	A(+) Backlit	5v thru current limiting resistor see LCD manual for max current
16	K(-) Backlit	0v

The code provided writes HELLO WORLD! in the first line and LINE 2 in the second line, just for demo. Modify it for your purpose. download the source and hex from the link below.