Help with Nodemcu

[Karthik rajagopal]

Hi all,
I started my project where I use a shift register to transfer data from the external circuit to the nodemcu. Since it is a 5-bit data, I use only 5 pins of the shift register and connected it to D2, D3, D5, D6, D7 GPIO pins of the Eps8266 board. The problem that I face is that the board fails to connect to Wi-Fi if I have any of the wires connected from the shift register to the board during start up. It connects only when I remove all the wires that goes from the shift register to the nodemcu module.
I am using 74HC595 as the shift register and 3.3v to power it. I don't have any other peripherals connected to the board. What could be the reason for this problem?
Thanks in advance.

 

[Harald Kapp]

The culprit is possibly D3.This pin has a special function during boot, see "Best Pins to Use – ESP8266". Use other pins instead, e.g. D1, D2, D5. D6, D7.

Why do you use the external shift register at all? You can directly read a serial data stream e.g. using the I²C interface of the nodemcu. Saves you the chip and a few pins.

 

[Karthik rajagopal]

The culprit is possibly D3.This pin has a special function during boot, see "Best Pins to Use – ESP8266". Use other pins instead, e.g. D1, D2, D5. D6, D7.

Why do you use the external shift register at all? You can directly read a serial data stream e.g. using the I²C interface of the nodemcu. Saves you the chip and a few pins.

Thanks for the reply.
The link was really informative. Thanks for sharing it.
Yes, I even tried out i2c at first ,as my communication is between msp432P401r launchpad and nodemcu. But I didn't get a proper communication between them. Since I was running out of time I used this to accomplish the communication. I will definitely figure that out.