1. Asst. Prof. Dr. Alper SISMAN
Practice
Asst. Prof. Dr. Alper SISMAN

2. Keypad/7-Segment Display
Matrix Keypad
GND output keypad
Serial output keypad
Dipswitches
7-Segment Display
Ex. Circuit (HW details
resistors etc.)

3. 7-Segment display Write all decimal numbers on the 7-segment.
Design a simple counter (0-9) that counts the seconds.

4. Alphanumeric LCD Display

5. Frequently used LCD commands

6. LCD Init.

7. Use LCD in 4-bit mode #include "STM32F4xx.h" #define RS 32;
#define EN 8;
#define databits GPIOD->ODR
void SystemInit(){
(*((int*)0xE000ED88))|=0x0F00000; // Floating Point donanimini aktiflestir.
RCC->AHB1ENR |= 0x F; //
GPIOD->MODER = 0x ;
GPIOD->OTYPER = 0x F;
//GPIOD->PUPDR = 0x ;
GPIOD->OSPEEDR= 0xFFFFFFFF
GPIOB->MODER = 0x ;
GPIOB->OTYPER = 0x ;
//GPIOB->PUPDR = 0x ;
GPIOB->OSPEEDR= 0xFFFFFFFF; }

8. void cmd(unsigned char c){
GPIOB->BSRRH = RS;
delayyus(50);
GPIOD->ODR = (c >> 4);
LCD_STROBE();
databits = (c); }
void delayyus(int delay0)
{ delay0-delay0*4;
while (delay0--) {} }
void LCD_STROBE(void) {
GPIOB->BSRRL = EN;
delayyus(1); //1us bekle
GPIOB->BSRRH = EN; }
void clear(void) {
cmd(0x01);
delayyus(2000); }
void data (unsigned char c) {
GPIOB->BSRRL = RS;
delayyus(50); //50us bekle
databits = (c >> 4);
LCD_STROBE();
databits = (c);
LCD_STROBE();}
void string1(const char *q) {
while(*q)
data(*q++); }}

9. void lcd_init() {
delayy1s(60000);
cmd(0x38);
delayy1s(4000);
delayy1s(400);
cmd(0x28);
cmd(0x0c);
clear();
cmd(0x6); }
int main (){
delayyus(50000);
lcd_init();
while(1) {
cmd(0x80);
string1("HELLO WORLD");
cmd(0xc0);
string1("IT IS WORKING"); }

10. Matrix Keypad

11. Homework
Write a C code that gets the pushed button if the matrix keypad is used in previous slide.
The ASCII code of the pushed button should be written on a seven-segment display.
Design the HW and Firmware