In the previous tutorial we saw how to blink an LED using CloudX board, but in some projects we might need to write to a PORT or a group of pins at the same time. For eg., for designing an 8 LED chaser, writing to pins one after the other makes your code look so bulky but writing to a PORT at once for this kind of projects will make your code look neat and more efficient.

A PORT is a group of pins associated to the same register of a microcontroller. So the controller can control all the pins associated with a particular port at the same time. Usually a 8-bit microcontroller will have 8 bit ports, 16-bit microcontroller have 16 bit ports and 32-bit microcontroller will have 32 bit ports.

In our case the CloudX microcontroller has 2 ports, PORT1 and PORT2. pin1 to pin8 are associated to PORT1 and pin9 to pin16 are associated with PORT2. Since it is an 8-bit microcontroller we can write to 8 pins at a time.

In order to write to PORTs, firstly we need to configure the pins as INPUT / OUTPUT. In this tutorial we are going to write to a PORT and verify it using LEDs. So basically we need to make all pins as OUTPUT pins. So we can use portMode(1, 0b00000000), this will make all 8 pins associated with PORT1 as output pins. For eg. if we use portMode(1, 0b11111111), it will make all pins as INPUTS. The prefix “0b” indicates a binary number.

After that we can write the logic status (HIGH or LOW) to each pins by using portWrite(1, 0b11110000), this will make first 4 pins of PORT1 HIGH and remaining 4 pins as LOW.

In both portMode and portWrite functions, the 1^st parameter represents the port you are writing to, while the 2^nd parameter represents the data you are writing to the port. For eg. in portMode(1, 0b01001001 ) we are loading the value 0b01001001 to PORT1 for configuration. Thus pin1 (Least Significant Bit) is configured as input and pin2 as output etc.

Components Required

• CloudX Microcontroller Board (Controller and SoftCard)
• LED – 8
• 220Ω Resistors – 8
• Male – Male jumper wires

Circuit Diagram

Programming

#include<CloudX\M633.h>
setup() {
  //setup here
  portMode(1, 0b00000000);
  loop() {
    //Program here
    portWrite(1, 0b11110000);
  }
}

In the code, initially we are setting all PORT1 pins as output using portMode, then we are setting first 4 pins as LOW and remaining 4 pins as HIGH using portWrite. You can feel free to tweak the code to flashing or chasing LEDs.

Hardware Experiment