DC motor speed and direction control with PIC18F4550 and CCS C

DC motor control with PIC18F4550 and H-Bridge

The microcontroller PIC18F4550 has two CCP modules CCP1 and CCP2, the CCP1 module is implemented as a standard CCP module with Enhanced PWM capabilities. These include the provision for 2 or 4 output channels, user-selectable polarity, dead-band control and automatic shutdown and restart.
The Enhanced PWM mode provides additional PWM output options for a broader range of control applications. The module is a backward compatible version of the standard CCP module and offers up to four outputs, designated P1A through P1D.
This topic shows how to use the enhanced PWM as a Full-Bridge Mode to control DC motor speed and direction.
In Full-Bridge Output mode, four pins are used as outputs; however, only two outputs are active at a time. In the Forward mode, pin P1A is continuously active and pin P1D is modulated. In the Reverse mode, pin P1C is continuously active and pin P1B is modulated.
P1A, P1B, P1C and P1D outputs are multiplexed with the PORTC<2>, PORTD<5>, PORTD<6> and PORTD<7> data latches. The TRISC<2>, TRISD<5>, TRISD<6> and TRISD<7> bits must be cleared to make the P1A, P1B, P1C and P1D pins outputs.
The motor speed is controlled when the PWM duty cycle changes.
An H-Bridge circuit is used to reverse motor terminals which gives us the ability to change rotation direction.

Related topics:
DC motor speed control with PIC18F4550 and CCS PIC C
PIC18F4550 ADC example with CCS PIC C compiler
PIC18F4550 PWM example using CCS PIC C

DC motor control with PIC18F4550 microcontroller circuit:
The following circuit schematic shows project circuit.
PIC18F4550 DC motor speed direction control circuit
PORTB internal weak pull-ups are enabled in the software.
There are 3 pushbuttons in the circuit 2 of them to choose rotation direction and the other one stops the motor. The two LEDs indicate rotation direction, if Direction 1 button is pressed the motor moves in the first direction and LED 1 on and the same thing for Direction 2 button and LED 2. The motor speed is controlled from potentiometer connected to RA0 (analog channel 0). The microcontroller PIC18F4550 reads analog data from channel 0 and use the digital value to set the PWM duty cycle.
The PWM frequency is 500Hz.
The basic elements of the H-bridge are the four MOSFETs (2 N-type and 2 P-type).
PIC18F4550 microcontroller internal oscillator is used and set to 8MHz.

DC motor control with PIC18F4550 CCS PIC C code:
PIC18F4550 Timer2 is configured to generate a PWM frequency of 500Hz and the microcontroller runs with its internal oscillator at 8MHz.
The microcontroller PIC18F4550 reads RA0 analog value and stores the digital value on variable (i), this variable is used to set the PWM duty cycle.

DC motor control with PIC18F4550 video:
The following video shows more about this project with hardware circuit.

Reference:
Microchip PIC18F4550 datasheet.

2 comments

  1. I wanted to build this circuit as a way of controlling a model railway but when I try putting the code into MPLAB X IDE v5.5 it keeps giving me errors, I’ve never programmed before so don’t know about C++ and don’t know if ive missed a bit of coding that it needs to run,

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