Hi.
I can’t see the file you shared.
I asked for permission.
Regards,
Sara

I have given permission. 

Hi.
That error is usually related to some issue with the hardware.
It may be an insufficient power supply, a short circuit, wrong connections in the circuit, or using GPIOs that are not suitable for what you want to do.
What does your code do? And what peripherals do you have attached to your board?
Regards,
Sara
 

I have uploaded screen shot of error below 
 
https://drive.google.com/drive/folders/1LUGHdtSeS4mKwmOMhHKw8W7HI5kwC6jx?usp=sharing
 
I am referring MODULE 7- UNIT NO 3 AND 4 of the book “Lean ESP32” .

Hi.
Do you get that error in which board? The sender or the receiver? Or both?
Try to upload the code without any peripherals attached and see the result.
Double-check all the connections of your circuit. Especially the DS18B20 sensor. The sensor orientation may be confusing.
Regards,
Sara

Hi,
I have attach only capacitor. No other peripherals. I think, error is because of timer interrupt. 
We are only focusing on sender code 1st. 
on receiver side, we edited code & attach only potentiometer. 
 

Hi.
 
But do you still get the errors with those modifications?
 
Does it work with the receiver?
 
For the sender, are you using the same code we use in the course, or have you modified it?
 
Regards,
Sara

We are running code as it is by referring MODULE 7- UNIT NO 3 AND 4 of the book “Lean ESP32”
1st we will solve sender side error.

Hi again.
I just tested the code again, and it uploaded fine, and it is working fine.
So, I really believe that the problem is something related to the circuit.
Regards,
Sara

I am referring MODULE 7- UNIT NO 3 AND 4 of the book “Lean ESP32” .
Trial-1: 
board-1: client-1 = everything is ok. Broker address of rpi, wifi name & password change. 
board-2: client-2= Broker address of rpi, wifi name & password change. Disconneting from MQTT. This is coming. 
Trial-2: 
board-2: client-2= I have flash client-1 code & its working fine. 
This means, board-2 is hardware no issues. 
What can be other debug methods to check, why it is disconnecting. 
 

Hi again.

So, you don’t have the brownout error now?

It is very difficult to find out what might be wrong.

Does your ESP is on the same network as the RPi? Do you have a Wi-Fi booster or something? Sometimes wi-fi boosters interfere with MQTT messages.

I’ve just tested the code, and as you can see on the print screen, it is working properly.

I don’t know what else I can do to help 😐

Regards,
Sara

1: That error still exist, so we change board.
2: we are using custom board on which code & output working fine. 
3: On below board, it is showing mqtt disconnect msg. Its connected to home router (no wi-fi repeater), ip address of rpi is checked, rpi is ON. 
https://www.banggood.in/LILYGO-TTGO-T-Energy-ESP32-8MByte-PSRAM-WiFi-bluetooth-Module-18650-Battery-ESP32-WROVER-IB-Development-Board-p-1427125.html?cur_warehouse=CN&rmmds=search
Do u have alternate solution on nodeMCU board. I mean, 2 nodeMCU board communication with rpi, 

Hi again.

I really don’t know how to solve that issue because I have no idea what might be wrong 🙁

How are you powering that board? Do you think there may be some power issue?

Yes, we have a similar project for ESP8266 boards.
I see that you have access to the “Home Automation using ESP8266” eBook. Go to page 428. There is a similar project.

Regards,
Sara