Pic Microcontroller Block Diagram 3f1d2v

PIC Microcontrollers

Block Diagram of PIC 16F 877A :Franklin Francis

PART DETAILS • If we compare 8051 and the block diagram of PIC above we have the following additions. – AD converter, Capture control modules, PWM, Interrupts increased and WDT near U module , i2c in Serial Communication module and EEPROM in memory module.

Power Supply

• BOR- Brown out reset. – If Microcontroller is switched off suddenly or due to electrical noises . – There can be a situation for the microcontroller to create an out of control activity. – To prevent this uC usually has its own built in circuit for brown out reset. • This would reset all the hardwares in the circuit. • External reset pin is named by MCLR. • Serves as external reset of microcontroller by applying logic 0 or 1, depending on uC. • Incase we don’t have a BOR ckt an external can be made.

Memory • The PIC 16f877a has three kinds of memory… – RAM, ROM, EEPROM. ROM : Where you load programs and we also call it the program memory. It is made in FLASH technology. ( Flash s fast writing and unlimited times of writing)

• EEPROM: – The contents is permanently saved, even upon the power goes off. – There are 256 locations and we can change the details. – Used to save data, results of operations and for latter working.

• RAM: Stores data till the power is available hence the name volatile. – Two parts • a) General purpose • b) SFR • Both these groups data will be lost during power outage. • The functions of the microcontroller would be different and don’t have things in common.

General Purpose s • General-purpose s are used for storing temporary data and results created during operation. • The variable created has a location that is known by the microcontroller and uC can access it during the course of the execution of the program.

Special Function s • They are s in RAM, but their function is predetermined during the manufacturing process and cannot be changed. • Since their bits are physically connected to particular circuits on the chip any changes on SFR directly changes the operations of the microcontroller.

RAM Memory Bank • RAM memory banks are partitioned in Four banks. • Two bits of STATUS s decides which bank is chosen. • To facilitate operations – SFRS have same matching address in all the banks.

BIT WISE TABLE of SFRs