Packet too big message

• Hardware model + communication type : Arduino UNO with ESP8266
• Smartphone OS : Android 10
• Blynk server
• Blynk Library version : 1.1.0

Hi, now I write a book about Blynk. Because I want to control a RGB LED by Blynk, so I created 3 datastreams and used slider and zeRGBa widgets like the following. But it doesn’t work while prints the message “Packet too big”. I already found other questions about the message in this forum. But they weren’t helpful. When I use the blynk legacy app (not, it works very well.

#define BLYNK_PRINT Serial

#define BLYNK_TEMPLATE_ID "TMPLjuE1kn3d"

#include <ESP8266_Lib.h>
#include <BlynkSimpleShieldEsp8266.h>

char auth[] = BLYNK_AUTH_TOKEN;

char ssid[] = "";
char pass[] = "";

#include <SoftwareSerial.h>
SoftwareSerial EspSerial(6, 7); // RX, TX

#define ESP8266_BAUD 115200

ESP8266 wifi(&EspSerial);

void setup()


  Blynk.begin(auth, wifi, ssid, pass);

void loop()

The SoftwareSerial library running on an Uno can’t emulate a serial port which will run successfully at this sort of baud rate. The Uno simply doesn’t have the processing power to make this work consistently.

The solution is to configure your ESP-01 to communicate at a lower baud rate (9600 preferably) and use the same baud rate as your ESP8266_BAUD in your sketch.

Alternatively, you can use the UNO’s hardware serial port for communication with the ESP-01 (the hardware serial port is capable of much higher baud rates) and use a software serial port at 9600 for debugging. The problem with this approach is that you then need a TTL to USB adapter (an FTDI adapter) to allow you to view the serial debug messages on your computer.

A slightly better approach is to use a Mega, which has 3 hardware serial ports.

An even better approach is to throw the Arduino and ESP-01 combination in the bin and use a WiFi capable board such as the NodeMCU or ESP32.

More info on serial ports here…


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Thanks Pete!! I changed the baud rate to 9600 as you recommend. It works well. Even though I also want to use Arduino Mega but I already made an arduino kit includes Arduino UNO so I can’t change it.
Anyway it works well so it doesn’t matter anymore.
I finished my book few months ago but blynk changed so many things nowadays, I edit the book totally.
Thanks again!

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