1. Teachers Name : Suman Sarker Telecommunication Technology Subject Name : Microcontroller & Embedded System Subject Code : 6871 Semester : 7th Department : Electronics Ideal Institute Of Science & Technology (IIST)

2. LECTURE-07 CH-08 CH-08 INPUT/OUTPUT

3. INPUT / OUTPUT PORTS In order for the microcontroller to be useful, it has to be connected to additional electronics, i.e. peripherals. Each microcontroller has one or more registers connected to the microcontroller I/O pins. Such connections make I/O ports. Why input/output? Because you can change a pin function as you wish..

4. For example, suppose you want your device to turn on/off three signal LEDs and simultaneously monitor the logic state of five sensors or push buttons. Some of the ports need to be configured so as to have three outputs (connected to LEDs) and five inputs (connected to sensors). It can be easily done from within the software, which means that a pin function can be changed during the operation

6. One of the important features of input/output (I/O) pins is a maximum current they can handle. For most microcontrollers, current supplied from one pin is sufficient to activate a LED or some other low- consumption device (10-20 mA). Each I/O port is usually under control of one SFR, which means that each bit of that register determines the state of the corresponding microcontroller pin. For example, by writing a logic one (1) to some of the register bits, the appropriate microcontroller pin is automatically

8. Next Lecture TIMER/COUNTER