• LCD-I2C

• Use Hal library
• Define lcd variable

LCD_I2C lcd;

• Init lcd (call function in main())

LCD_I2C_Init(&lcd,&hi2c2,address,width,height);

address: address of pcf8574 width: width of lcd height: height of lcd

• use function for your purpose:

LCD_I2C_SetCursor(&lcd, 0, 0);    //cursor on lcd, x is width, y is height
LCD_I2C_WriteString(&lcd,"hello world");

• PS2

• Use Hal library
• Define object PS2Buttons ps2;
• init 2 timer for ps2: timer1 for delay_us: prescaler=64-1, period=0xff timer2 for update: prescaler=6400-1, period=100-1 and enable interrupt for timer2
• In main(), call PS2_Init(&htim1,&ps2) for init ps2
• Overflow interrput timer for update buttons stage:

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim){
  if(htim->Instance == TIM2) PS2_Update();
}

or go to file stm32f1xx_it.c put PS2_Update() in TIM2_IRQHandler()

void TIM2_IRQHandler(void){
  PS2_Update();
}