About Arduino Mega 2560 with ESP8266-01 using Blynk.cloud Console

[bluealbertz1]

The idea behind the project is – the user is able to turn off and on the relay through a button hardwired to the chassis and through the Blynk app –

I’m currently working on a project that deals with multiple relays and servo motors as actuators. I was working with NodeMCU and Blynk Legacy for a while but later realized that I was going to be short on pins, as I need about at least 12 pins which the board couldn’t provide then I opted to use Mega 2560 with ESP8266-01 as Wi-Fi shield.

While configuring the console, I noticed that there is no option for Mega 2560, as well as the pins while configuring “Datastreams”:

I’m quite stuck here as I really do not know how I will be able to control the state of the relays without using the correct Digital pins. The only available pins in the “Digita Datastream” are pins from Arduino Uno (13 Digital Pins, 5 Analog Pins).

Is there anyway I can use the Arduino Mega pins despite being limited on “pins” in the Blynk.cloud console? Thank you!

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These are the pins connected to the Arduino Mega:

const int RELAY_PIN  = 22;
const int RELAY2_PIN  = 23;
const int RELAY3_PIN  = 24;
const int RELAY4_PIN  = 25;

#define trig 32
#define echo 33
#define triggerpin2 34
#define echopin2 35

const int BUTTON_PIN = 42;
const int BUTTON2_PIN = 43;
const int BUTTON3_PIN = 44;
const int BUTTON4_PIN = 45;

[Mosaad]

I will just suggest you solutions but really not sure of it
first solution is to use esp32 instead of Arduino Mega as it gives you more pins .
second solution is to try to use the given pins (13 and 5 analogue) and check if that will work with the Mega and if also if these all pins can work as digital , give it a try .
Regards

[PeteKnight]

@bluealbertz1

I need about at least 12 pins which the board couldn’t provide then I opted to use Mega 2560 with ESP8266-01 as Wi-Fi shield.

That’s an awful choice, far better to go for an ESP32 or something like this…

ESP8266 16-way relay board using 2x 74HC595 controllers

I saw this post from @Vitokhv recently and decided to order one of these boards and have a play around with it. Here’s a link to another supplier on AliExpress who’s selling the same board: The boards are basically an ESP8266 with two 74HC595 shift registers that allow the 16 onboard relays to be controlled via just 4 GPIOs. They seem to be available in versions that work with a 5v, 12v or 24v supply voltage, and the relays are supposed to be capable of switching up to 250v at 10A each. …

or this…

Using the MCP23017 IO Expansion Board

EDIT NOVEMBER 2021… Anyone interested in controlling multiple relays may also want to take a look at this topic, which uses a pre-built 16-way relay board and 2x 74hc595 shift registers: END OF EDIT . I had a project recently where I wanted to use 5 physical buttons, with built-in LED indicators, to control 5 relays. That meant having 15 GPIOs available, so I built the project around an ESP32 dev board. I also needed a few more GPIO pins for other sensors, so by the time I was done I was o…

Also, don’t use digital pins, use virtual pins instead…

Using Virtual Pins to control physical devices

I thought I’d write a guide about how to use virtual pins with app widgets such as buttons, to control physical devices such as relays, LEDs etc… Why use virtual pins anyway? I’d always recommend using virtual pins over physical pins when developing your code. There are a number of reasons, but here are what I consider to be the main ones: Virtual pins are hardware independent. This means that it’s far easier to port your code from one hardware platform to another in future (when you realise…

Pete.

[bluealbertz1]

Thanks for replying. As for the suggestions…

a) The 13 pins of the Mega are already occupied with other modules (RTC, Esp8266-01 and Servo motors). To be precise, my pin configurations are:

1. Esp8266-01 [Pin 2, 3]
2. RTC [Pin 5, 6, 7]
3. Servo motors [Pin 8, 9, 10, 11]

• this leaves me no choice but to use other digital pins on the Arduino Mega

b) I could try using an Esp32, but I might encounter a similar problem with me using a NodeMCU. The problem was that the GPIO on the NodeMCU was very limited and some of the modules I’m using are malfunctioning due to the nature of the board.

[bluealbertz1]

Thanks for the suggestions. As to why I’m using digital pins over virtual pins is because the device I’m working on has physical buttons placed on it.

This is the fritzing of the project in question:

this is with the old layout using the nodemcu

This is the code to control the state of the relay using the said buttons.

void loop()
{
 lastButtonState = currentButtonState;
 
 currentButtonState = digitalRead(BUTTON_PIN);

  if (lastButtonState == HIGH && currentButtonState == LOW) {
      relayState = !relayState;
      digitalWrite(RELAY_PIN, relayState);
   }
}

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The button basically acts as a switch to turn off and on the relay and allow the servo to move. I guess what I’m trying to say is that, would it be possible to control the relay using the physical button and the virtual button from Blynk.

edit: I was able to use the physical buttons and the virtual buttons on the Blynk Legacy, but I opted to use the 2.0 because of the events feature for the sensor I’m using.

[PeteKnight]

@bluealbertz1

As to why I’m using digital pins over virtual pins is because the device I’m working on has physical buttons placed on it.

Yes, most of my devices also have physical switches attached to them, but I never use digital pins in Blynk.

@bluealbertz1

This is the code to control the state of the relay using the said buttons.

You shouldn’t put that stuff in your void loop when working with Blynk.
You should either use a timer to pill your physical switch, or attach an interrupt to it and use debounce code.

@bluealbertz1

would it be possible to control the relay using the physical button and the virtual button from Blynk.

Yes, that’s a sketch builder example to do just that…

Blynk Example Browser

@bluealbertz1

This is the fritzing of the project in question:

Very strange!

Pete.