NodeMCU ESP8266 I2C Adapter Low Power Issue with SHT31 Sensor LED Glowing Dim

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#1 21680926 24 Oct 2018 17:27

Derby Jhon Derby Jhon

Anonymous

Post #1
21680926 24 Oct 2018 17:27

Hello, I am using Node MCU Lolin withI2C adapter for ESP8266 and whenever I am trying to connect my SHT31 sensor with the adapter using I2C cable, while checking the power in sensor LED glows dimly.First I thought there might be an issue in the sensor so I have changed my sensor and faced the same issue again. Also, the sensor is working perfectly fine with Arduino I2C adapters, I am looking for some advice to avoid this cause, your leads will be a great help.
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#2 21680927 24 Oct 2018 17:30

Derby Jhon Derby Jhon

Anonymous

Post #2
21680927 24 Oct 2018 17:30

Note: I am giving 5v power supply to the Node MCU does It harm Node MCU in any way?
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#3 21680928 24 Oct 2018 17:43

Rick Curl Rick Curl

Anonymous

Post #3
21680928 24 Oct 2018 17:43

Hi Derby-Are you powering the Node MCU through the micro USB connector? 5 volts should be fine.Is the micro USB connector oriented so it faces the opposite direction from the I2C connector?I suggest disconnecting the SHT31 and then measure the voltage on the GND and +5 volt pins on the I2C connector on the I2C adapter.Can you communicate with the Node MCU through WiFi or USB?-Rick
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#4 21680929 24 Oct 2018 18:06

vaibhav sharma vaibhav sharma

Anonymous

Post #4
21680929 24 Oct 2018 18:06

I went to this link.Can you tell me the reading of the capacitor they are using? If it is using more than 10uF then just bypass it remove this capacitor and solder the open circuit. it will work fineThere is no need of capacitor here. yes, a few nF capacitors can remove the voltage spikes. But using the capacitor that too without any resistance will increase the time constant of the device and can cause delayed charging and discharging. It's better to bypass this capacitor and try connecting it directly.also as @RickCurl said to check the voltage at Vin pin.
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#5 21680930 25 Oct 2018 16:58

Derby Jhon Derby Jhon

Anonymous

Post #5
21680930 25 Oct 2018 16:58

Hi Rick,Yes, I am connecting 5volts supply through micro USB, also USB and the I2C connector is opposite to each while connecting it with the I2C shield.
I just powered up my esp8266 and connected it with and while checking voltage on the GND and +5 volt pins then the output is around 0.24 v only.
#6 21680931 25 Oct 2018 22:01

Rick Curl Rick Curl

Anonymous

Post #6
21680931 25 Oct 2018 22:01

Try disconnecting the ESP8266 from the I2C shield. Then measure the 5 volts on the header pins of the ESP8266. Did the voltage increase any?
-Rick
#7 21680932 27 Oct 2018 18:47

vaibhav sharma vaibhav sharma

Anonymous

Post #7
21680932 27 Oct 2018 18:47

Here In this shield, they are giving power to I2C device from Vin pin. Whereas, in nodeMCU the vin pin is the input pin for 5v. That's why you are getting just 0.24 v at this pin. So better remove the shield and give the voltage to the sensor form NodeMcu's 3v pin.
#8 21680933 30 Oct 2018 16:50

Cologne LED Cologne LED

Anonymous

Post #8
21680933 30 Oct 2018 16:50

If it is using more than 10uF then just bypass it remove this capacitor and solder the open circuit. it will work fine.
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Topic summary

A NodeMCU Lolin ESP8266 board connected to an I2C adapter experiences a low power issue when interfacing with an SHT31 sensor, indicated by a dimly glowing sensor LED. The sensor functions correctly with Arduino I2C adapters, suggesting a wiring or power supply incompatibility with the NodeMCU setup. The NodeMCU is powered via micro USB at 5V, which is appropriate. Voltage measurements at the I2C adapter's Vin pin show only about 0.24V, much lower than expected. This occurs because the I2C shield supplies power to the sensor from its Vin pin, which on the NodeMCU is an input pin rather than an output. The recommended solution is to bypass the shield's Vin power line and supply the sensor directly from the NodeMCU's 3.3V pin. Additionally, the presence of a large capacitor (greater than 10µF) on the power line of the I2C adapter can cause delayed charging and voltage drop; removing or bypassing this capacitor may improve power delivery and sensor operation.
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NodeMCU ESP8266 I2C Adapter Low Power Issue with SHT31 Sensor LED Glowing Dim

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