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Introduction to PIC18F4520

Hi Friends! Hope you are doing well. In this platform we mainly cover information related to engineering and technology, no matter if you are a newbie or experts, you'll find something handy that may resonate with your field of interest. Today, I'll unlock the details on the Introduction to PIC18F4520. It is an 8-bit enhanced flash PIC microcontroller that comes with nanoWatt technology and is based on RISC architecture. Many electronic applications house this controller and cover wide areas ranging from home appliances, industrial automation, security system and end-user products. This microcontroller has made a renowned place in the market and becomes a major concern for university students for designing their projects, setting them free from the use of a plethora of components for a specific purpose, as this controller comes with inbuilt peripheral with the ability to perform multiple functions on a single chip. In this tutorial, I'll cover each and everything related to PIC18F4520, its pinout, main features, block diagram, and applications. Let's dive right in and nail down everything you need to know.

Introduction to PIC18F4520

• PIC18F4520 is a PIC microcontroller, introduced Microchip, and mainly used in automation and embedded systems. It comes in three packages known as PDIP, QFN, and TQFP where the first one is 40-pin (mostly used) while other two come with a 44-pin interface.
• This microcontroller version comes with CPU, timers, 10-Bit ADC and other peripherals that are mainly used to develop a connection with external devices.
• This PIC version, like other models in the PIC community, contains everything that is required to make an embedded system and drive automation.
• The PIC18F4520 contains 256 bytes of EEPROM data memory, 1536 bytes of RAM, and program memory of 32K.
• It also incorporates 2 Comparators,10-bit Analog-to-Digital (A/D) converter with 13 channels, and houses decent memory endurance around 1,000,000 for EEPROM and 100,000 for program memory.
• The Enhanced Universal Asynchronous Receiver Transmitter (EUSART) feature is useful for developing the serial communication with other devices.

• The asynchronous serial port is added on the chip that can be interfaced both ways i.e. 3-wire Serial Peripheral Interface (SPI™) or the 2-wire Inter-Integrated Circuit (I²C™) Bus.

The functions that make this device unique in terms of functionality and ease of use include

• Wide operating voltage range (2.0V-5.5V)
• Multiplexed Master Clear with pull-up/input pin
• In-Circuit Serial Programming™ (ICSP™) via two pins
• Power-Saving Sleep mode
• C compiler optimized architecture
• Industrial and Extended Temperature range
• Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)
• Power-on Reset (POR)
• In-Circuit Debug (ICD) via two pins
• Brown-out Reset (BOR) with software control option
• Watchdog Timer (WDT)

1. PIC18F4520 Pinout and Description

You have got a clear idea about this PIC18F4520 model. In this section, we jot down the pinout of the controller and cover a detailed description of each pin.

PIC18F4520 Pinout

Following figure shows the pinout of PIC18F4520.

• The PDIP module comes with 40-pin interface while other two QFN and TQFP contain 44-pin on each module.
• The former module is mainly used for developing individual projects while the other two are incorporated in industrial electronic devices.

Pin Description

Every pin on the module comes with a unique function, used as per the requirement of the project. And some pins incorporate multiple functions. The following figure shows the complete pinout description of this tiny PIC module.

Pin#	Pin Name	Pin Description
2	RA0/AN0 RA0 AN0	Digital I/O Pin Analog Input 0 Pin
3	RA1/AN1 RA1 AN1	Digital I/O Pin Analog Input 1 Pin
4	RA2/AN/VREF- RA2 AN2 VREF-	Digital I/O Pin Analog Input 2 Pin ADC Reference Input Voltage (low)
5	RA3/AN/VREF+ RA3 AN3 VREF+	Digital I/O Pin Analog Input 3 Pin ADC Reference Input Voltage (high)
6	RA4/T0CKI/C1OUT RA4 T0CKI C1OUT	Digital I/O Pin External clock input for Timer0 Output Comparator 1
7	RA5/AN4/SS/HLVDIN/C2OUT RA5 AN4 SS HLVDIN C2OUT	Digital I/O Pin Analog Input 4 Pin Slave Select input for SPI (High, Low) Detect Input for Low Voltage Output Comparator 2
33	RB0/INT0/FLT0/AN12 RB0 INT0 FLT0 AN12	PORTB can be programmed with software Digital I/O Pin External Interrupt 0 Fault Input for Enhanced CCP1 Analog Input
34	RB1/INT1/AN10 RB1 INT1 AN10	Digital I/O Pin External Interrupt 1 Analog input 10
35	RB2/INT2/AN8 RB2 INT2 AN8	Digital I/O Pin External Interrupt 2 Analog input 8
36	RB3/CCP2 RB3 AN9 CCP2	Digital I/O Pin Analog input 9 Output for Compare2 and PWM2, and Input for Capture2
37	RB4/KBI0/AN11 RB4 KBI0 AN11	Digital I/O Pin Interrupt-on-change pin Analog input 11
38	RB5/KBI1/PGM RB5 KBI1 PGM	Digital I/O Pin Interrupt-on-change pin ICSP programming enable pin for low voltage
39	RB6/KBI2/PGC RB6 KBI2 PGC	Digital I/O Pin Interrupt-on-change pin ICSP programming clock and In-Circuit Debugger pin
40	RB7/KBI3/PGD RB7 KBI3 PGD	Digital I/O Pin Interrupt-on-change pin ICSP programming data and In-Circuit Debugger pin
15	RC0/T1OSO/T13CKI RC0 T1OSO T13CKI	Digital I/O Pin Oscillator output for Timer1 External clock input for Timer1/Timer3
16	RC1/T1OSI/CCP2 RC1 T1OSI CCP2	Digital I/O Pin Oscillator input for Timer1 Output for Compare2 and PWM2, Input for Capture2
17	RC2/CCP1/P1A RC2 CCP1 P1A	Digital I/O Pin Output for Compare1 and PWM1, Input for Capture1 Enhanced CCP1 Output
18	RC3/SCK/SCL RC3 SCK SCL	Digital I/O Pin SPI Module Synchronous serial clock input/output I2C Module Synchronous serial clock input/output
23	RC4/SDI/SDA RC4 SDI SDA	Digital I/O Pin SPI Data-In Pin I2C Data I/O Pin
24	RC5/SDO RC5 SDO	Digital I/O Pin SPI Data-Out Pin
25	RC6/TX/CK RC6 TX CK	Digital I/O Pin Asynchronous Transmit (USART) Synchronous Clock (USART)
26	RC7/RX/DT RC7 RX DT	Digital I/O Pin Asynchronous Receive (USART) Synchronous Data (USART)
19	RD0/PSP0	Digital I/O Pin Parallel Slave Port (PSP) for D0 with TTL input buffers
20	RD1/PSP1	Digital I/O Pin Parallel Slave Port for D1 with TTL input buffers
21	RD2/PSP2	Digital I/O Pin Parallel Slave Port for D2 with TTL input buffers
22	RD3/PSP3	Digital I/O Pin Parallel Slave Port for D3 with TTL input buffers
27	RD4/PSP4	Digital I/O Pin Parallel Slave Port for D4 with TTL input buffers
28	RD5/PSP5	Digital I/O Pin Parallel Slave Port for D5 with TTL input buffers
29	RD6/PSP6	Digital I/O Pin Parallel Slave Port for D6 with TTL input buffers
30	RD7/PSP7	Digital I/O Pin Parallel Slave Port for D7 with TTL input buffers
8	RE0/RD/AN5 RE0 RD AN5	Digital I/O Pin PSP Read Control Analog input 5 Pin
9	RE1/WR/AN6 RE1 WR AN6	Digital I/O Pin PSP Write Control Analog input 6 Pin
10	RE2/CS/AN7 RE2 CS AN7	Digital I/O Pin PSP Chip Select Control Analog input 7 Pin
1	MCLR/VPP MCLR VPP	ICSP Programming Enable Pin Master Clear Active Low Reset Pin
13	OSC1/CLKI OSC1 CLKI	Crystal Oscillator Input Pin
14	OSC2/CLKO/RA6 OSC2 CLKO RA6	Crystal Oscillator Output Pin
12,31	VSS	Ground pin
11,32	VDD	Voltage pin

• This table will help you understand the function associated with each pin.

2. PIC18F4520 Features

Features are very important for any device that makes it unique from its counterparts. The following figure shows the complete features of PIC18F4520.

PIC18F4520 Features
No. of Pins	40
CPU	8-Bit PIC
Operating Voltage	2 to 5.5 V
Program Memory	32K
Program Memory (Instructions)	16384
RAM	1536 Bytes
EEPROM	256 Bytes
ADC Number of Channels	10-Bit 13
I/O Ports (5) I/O Pins	A,B,C,D,E 36
Packages	40-pin PDIP 44-pin QFN 44-pin TQFP
External Oscillator	up to 40 MHz
Timer (4)	16-Bit Timer (3) 8-Bit Timer (1)
USART Protocol	1
I2C Protocol	Yes
SPI Protocol	Yes
Brown-out Reset	Yes
Watchdog Timer	Yes
Comparators	2
Master Synchronous Serial Port (MSSP) module	1
Capture/Compare/PWM	16bit/16bit/10bit
Power Saving Sleep Mode	Yes
Selectable Oscillator Option	Yes
Operating High-current sink/source Each pin	25mA
Programmable High/Low-Voltage Detect	-Yes
Oscillator Start-up Timer	Yes

• These features help you identify the main characteristics of the controller that are appropriate for designing and developing for the certain project.

3. PIC18F4520 Functions

This PIC model is capable of performing many functions similar to other controllers in the PIC community. Following are the main functions of PIC18F4520.

Timer

PIC18F4520 comes with three 16-bit and one 8-bit timer that can be used as a timer as well as a counter. All three timers contain internal and external clock select capability. The timer mode mainly increments the instruction cycle while the counter mode is used to increment the rising and falling edge of the pin.

Brown Out Reset (BOR)

The BOR is a very useful function that allows this controller to reset once the Vdd (voltage supply) drops below a brownout threshold voltage. The multiple voltage ranges are used and provided to protect the chip once the power drops at the voltage supply line. The Power Up Timer must be kept enabled, in order to put the delay in returning the device from a BOR function, t The BOR mode can be configured both ways i.e. through BOREN settings in a register as well through programming.

In-Circuit Serial Programming

In-circuit serial programming (ICSP), also called In-system programming (ISP), is a feature added to this device that makes it enable to be programmed in the required system after installation, setting it free from programming the device before making it compatible with the certain project.

USART

This controller version comes with USART module, that stands for Universal Synchronous and Asynchronous Receiver and Transmitter, and is mainly used for setting up the serial communication with external devices. There are two parts of this module called TX and RX where former is known as transmitting component that is used for transmitting serial data while later is known as receiving component, used for receiving the serial data across the attached devices.

Watchdog Timer

PIC18F4520 contains a built-in watchdog timer that brings the controller in reset position if the program hangs up during compilation or gets stuck in the infinite loop. It is worth mentioning here, this timer must be reset to the initial value after every 3 instructions in order to avoid it going to zero value in normal conditions. The watchdog timer is more or less a countdown timer that starts from 1000 and ultimately goes down to zero.

Power On Reset

Power On Reset function is very helpful and resets the controller and starts it from scratch when Vdd raises above a certain threshold value. This function is very useful to prevent the device from malfunctioning.

Power Managed Modes

PIC18F4520 provides total 7 operating modes that help in more efficient power management. These modes offer multiple options for selective power conservation in a variety of applications. The power managed modes are mainly divided into three main categories called:

• Run modes
• Sleep mode
• Idle modes

These categories help in identifying the areas of the device that are clocked at a specific speed. The Idle and Run modes can operate in any of three clock sources named primary, secondary, and internal oscillator block while Sleep mode is not involved in any clock source. The switching feature is added in the power managed modes that use the Timer1 oscillator as a replacement of a primary oscillator. All clocks will be cleared and stopped working in the Sleep mode.

Master Clear Reset (MCLR)

The MCLR pin is used for calling the external reset for the chip. The reset is triggered by keeping this pin at a LOW value and is not dependent on the internal resets. The noise filter is added in the MCLR executing process that helps in detecting and removing the small pulses. The MCLRE configuration bit can also be used to disable MCLR input.

4. PIC Compiler

• Microchip comes with its own standard compiler for the PIC controller called MPLAB C18 Compiler. You can get this compiler online from the Official Microchip Site.
•  MikroC Pro For PIC is a third party software mainly used as a replacement of Microchip standard compiler.
• These Top 3 PIC C Compilers give you many options to choose from to pick any compiler as per your needs and demands.
• The code written in the compiler generates a hex file which is then uploaded to the microcontroller to execute the number of instructions.
• The PICKit3 is a standard PIC burner, mainly used for burning the code in the controller. There are other burners also available in the market but PICKit3 is mostly used and preferred for the PIC controllers.

5. PIC18F4520 Memory Layout and Working

The memory of the module is very useful for storing a number of instruction which can be divided into three major types: Program Memory Data EEPROM Data RAM Let's discuss each memory one by one and highlight the main functions associated with them.

Program Memory

The Program memory, also known as ROM memory or Non-Volatile memory, stores the running program permanently. It doesn't depend on the power supply i.e. stores the program in the absence of the main power supply.  The ROM memory is about 32K and is made with FLASH Technology.

Data EEPROM

This memory is similar to ROM memory in one way or the other and stores running program permanently with one limitation i.e. the instructions in EEPROM can be controlled and modified during the controller operation. The EEPROM comes with memory space around 256 bytes and can be accessed and addressed by multiple control registers.

Data RAM

RAM memory, also known as volatile memory, stores the program temporarily and removes the stored program once the power supply is removed. It is classified into two main parts called General-purpose registers (GPR) Special-function registers (SFR) This memory is volatile in nature as it stores the program temporarily and is power dependent i.e. once the power supply is turned off the instructions stored in the RAM will be removed. The RAM memory registers are the data holding places that can hold instruction, storage address, and any kind of data ranging from an individual character to bit sequence. The data memory can be employed as static RAM where each register comes with a 12-bit address. This memory is comprised of a total 16 banks and each bank contains a memory space of around 256 bytes. Let’s discuss few registers in details. STATUS Register. This register is mainly used to switch between the mentioned banks. Setting the fifth bit of this register indicates the performance of bank1 while resetting it will address bank 0. TRISA. This register plays a vital role to configure PORTA as an input or output. The value 1 describes it as an output and value 0 shows input. TRISB. This register is similar to TRISA and used for deciding the pins as an input or output of PORTB. W Register. This register is a GPR while all other described above belong to SFR. It is not associated with any register bank and is addressed by the program only. The required values are written on W register and moved to the target register before writing them down on the available ports.

6. PIC18F4520 Block Diagram

You have got a brief overview of pinout, its description and main features of the controller. In this section, we discuss the main block diagram of the microcontroller so you can get an idea how each function in the controller is related and connected to each other.

• PIC18F4520 comes with five ports where each port contains 8 pins except the E port that comes with 4 pins which also include MCLR (master clear pin).
• This device can be configured using 10 different oscillator modes where different capacitor values are required to generate acceptable oscillator operation. The user must test oscillator performance with the suitable VDD and temperature range for the required project.

7. PIC18F4520 Projects and Applications

• PIC18F4520 is widely used in home and industrial automation
• Student projects for motor controlling and sensor interfacing
• GPS and security systems
• Gas sensor projects
• Production of temperature data logger
• Serial Communication
• Central heating projects
• Embedded system

8. Why Use PIC MicroControllers

• PIC microcontrollers are widely used in multiple applications as they come with user-friendly interface and easy onboard architecture that requires little or no prior skills before getting familiar with the chip.
• They can perform a number of functions using minimum circuitry and are cheap in price as compared to other modules available in the market.
• Minimum power consumption is another ability that makes this controller an ideal choice for the projects where power limitation is a major concern.
• PIC controllers stay ahead of other Atmel controller like 8051 in terms of their higher processing speed and efficiency.

That's all for today. I hope this article has helped you got a complete overview of PIC18F4520 and the main functions associated with it. If you are unsure or feeling skeptical, you can ask me in the comment section below. I'd love to assist you in any way I can. Feel free to give your feedback and suggestions that help us provide you quality work based on your needs and requirements. Thanks for reading the article.