Drive LCD 16x2 with 4pin, Without I2C on STM32F407VG discovery board but you can use it for other microcontrollers.

attention: some unused peripheral are modified.

ALL YOU NEED IS THIS TWO PERIPHERALS:

• Timer (I wrote it for TIM1 with this settings.)
• GPIO

All pins are set on GPIOE:

d7 -> pin 15 as D7_Pin
d6 -> pin 14 as D6_Pin
d5 -> pin 13 as D5_Pin
d4 -> pin 12 as D4_Pin
E  -> pin 11 as E_Pin
RS -> pin 10 as RS_Pin
RW -> pin 9  as RW_Pin

Send some command to LCD for turn LCD On and responsible and select 4pin Mode._{(READ about commands in datasheet)}

Because we use 4pin mode we should split our character ASCII HEX to 4 highbit and 4 lowbit.

Then sending 4 highbit and 4 lowbit of character to LCD_send function with rs = 0 (for sending data we need rs = 0, more information in LCD_send)

Work like LCD_send_data but with rs = 1

At first we define RS_Pin with function rs input

RS_Pin must be 0 for sending data
RS_Pin must be 1 for sending data

In this step, char is 4 bit, so we send it by set our 4 Data Pin_(D4-D7), 1 or 0.

After that we set E_Pin, 1, to say to LCD that we sending data, read the pins! and give LCD some time, then set E_Pin to 0.

This function get a string, select string characters and send them to LCD_send_data function.

Select curser location with command._{(READ datasheet to know how it works)}

Send Clear-Screen command to LCD and give LCD some time.