DS18b20 nine sensor problems

[DavidVT]

Hello,
I have a nine sensor 1-wire string that is used to monitor my home heating system including an outside wood boiler.
The system has worked off a raspberry pi for several years.

My new project is to move this sensor string to an ESP8266.

I was able to configure all 9 sensors on the string and use the global feature to show the data on another ESP8266.

Unfortunatly the system stopped responding after a few minutes. Only disconnecting the string would bring the admin webpage back to me. I repeated this a few times and then returned the string to the Raspberry pi.

I have a 4k7 resistor at the start of the string, near the ESP8266. I believe the sensor string is probably pulling the power supply down.

Any suggestions? Frustrating as it worked great for a bit.

Thanks in advance for any guidance.

David

[DavidVT]

Update:
Since this is a nodemcu with the 5v Vin, I moved the one wire V+ to the Vin line. Now the unit seems to stay running and online.
I have it configured to show the connectivity via the red led. It is curious to see the red led go off and the blue blink every so often.
My uptime continues to increase and the temperatures are appropriate so I do not believe thr unit is rebooting. Curious is now seeing load at 100% all the time??

A few minutes later.....

** Spoke to soon..... I found the second remote unit 'fell off the web' when this first unit started working. Perhaps coincidence, but when I rebooted the second unit, the first locked up. I removed the 9 sensor string from the first (primary) unit and re-inserted the single sensor test string. Both units are working and the Load is low as before I started testing the 9 sensor string today. Back on the Pi, the nine sensor string works fine..

Review:
First unit nodemcu: has DHT22 and trying to get a nine sensor DS18b20 string to work. Today the Vin (5v) as the V+ to the one-wire string seemed to work better for a time but the load was at 100% with the Red and Blue LED's flashing from time to time...
Second unit nodemcu: has just a DHT22 and hoping to see the Global process echo the one wire sensor data to it. With one DS18b20 the Global process did work.
Both are setup to speak to an MQTT broker and that has been working ok. Even the 9 sensor data tested briefly above was sending to the MQTT broker.

Any thoughts??
David

[Zodiac69]

Hi DavidVT

Do you mind posting the two layouts?
It would make things clear as to what the difference is and what your setup is.

I personally would power the DS18b20's from 5V and have the data line connected to the ESP via a level shifter, i personally like this one.

[DavidVT]

Zodiac69
I will work on posting the layouts.
Do you have any opinion why the load is sitting at 100% ??
Thank you.

[Zodiac69]

Hi DavidVT

Not sure, but i have the same.
I have an EspEasy that read an DHT22 and an OLED to display the value communicating to Domoticz on a RPI and the load is also 100%

My unit update the display and report to the RPI every 30 sec.
I have looked around on the Forum, but was not able to see why i am running at 100% load.

As all it working for now, i have not look any further.

[DavidVT]

Here is my first try with Fritzing:
The cable is really over 100 feet long but has worked for years with the Pi.

NodemcuDHT22_oneWire_bb.png

[iron]

Here is my first try with Fritzing:
The cable is really over 100 feet long but has worked for years with the Pi.
NodemcuDHT22_oneWire_bb.png

Missing a pullup on the DHT22 ?

[Zodiac69]

So i found a circuit that show what a RPI I/O looks like, if we can find a ESP8266 I/O, then we can see why that is giving you issues

What i have found is that the ESP I/O pins have these options:
GPIO_PIN0 [31:11]
GPIO_PIN0_WAKEUP_ENABLE [10] R/W 0: disable; 1: enable GPIO wakeup CPU, only when GPIO_PIN0_INT_TYPE is 0x4 or 0x5
GPIO_PIN0_INT_TYPE [9:7] R/W 0: disable; 1: positive edge; 2: negative edge; 3: both types of edge; 4: low-level; 5: highlevel
GPIO_PIN0_DRIVER [2] R/W 1: open drain; 0: normal
GPIO_PIN0_SOURCE [0] R/W 1: sigma-delta; 0: GPIO_DATA
Not sure how the EspEasy set the pin up?

Are you pulling the DS18b20 data line to 5V via the 4K7?
I would not do that. See if you can put a level translator between your DS18b20 data line and the ESP8266 I/O pin.
The maximum input of the I/O is 3.3V, not sure what higher voltage will do, but i have read that it can damage your ESP I/O

[DavidVT]

Nice homework on the equiv pi circuit! I have never seen the programable pull up/dn circuit.

I am very curious how ESPEASY configures the port and how the development board adds to that.

I am considering going back to an arduino sketch only to try and learn where the cpu load is coming from. Perhaps next weekend.

Thank you

[DavidVT]

Update:
Today I swapped the powersupply from 1amp to 2amp.
Then I watched the unit start to work but eventually the load creeps up and the espeasy website becomes unresponsive.

Next I noticed leaving the devices web page active seemed to cause unresponsive faster.
Finally I turned off the global sync flag at the bottom of the tools/advanced page. That seems to have the most impact on improving my unresponsive issue!!

When I stopped the test, my mqtt broker was still receiving data from all nine sensors and the load was showing 4%!! That after a full 112 minutes of uptime.

With this new circuit seeming to working now, I will move on to moving the heating system graphs to a new system.

Summary: (after a two hr test sending to mqtt)
-The 9 DS18B20 sensor string remains being fed with 5v. On the next test I will drop that back to 3.3v and recheck reliability.
-The micro-usb power supply is 2amp.
-This is using the esp 12e nodemcu dev board
-The global sync flag is 'off' to prevent the unit from locking up with high load.