Comments on: ESP32 with Multiple DS18B20 Temperature Sensors

By: Jon

Jon — Thu, 29 Feb 2024 02:16:45 +0000

In reply to mrspeed. Try pdfserv.maximintegrated.com/en/an/AN148.pdf

By: Roger

Roger — Sun, 10 Dec 2023 23:01:45 +0000

There is a down side to having multiple DS18B20s on one line. First, you don’t know which sensor is which when the app prints out the temperature. Second, when a sensor fails, the new sensor can be in any order in the detection, so if your system depends on knowing the location of the reported data, the Dallas() function isn’t helpful until you physically nail down the locations. Third, the Dallas() function takes time to detect each sensor, and then adds an addition 850 ms minimum for each sensor’s conversion time. You can speed things up by starting the conversion, then go do something for 850+ ms, then come back and read the data and start another conversion. The following code is very fast, where X is the GPIO pin (or pins):

// — Dallas reader ————————————–
int dallas(int x) {
OneWire ds(x) ;
byte data0 ;
byte data1 ;
long result ;

ds.reset() ; ds.write(0xCC) ; // skip command ds.write(0xBE) ; // Read first 2 bytes of Scratchpad data0 = ds.read() ; data1 = ds.read() ; result = (data1 << 8) | data0 ; // round up (add 1/2 bit) and convert to degrees F times 100 result = (((result * 90) + 0x04) >> 3 ) + 3200 ; // F x 100 ds.reset() ; ds.write(0xCC) ; // skip command ds.write(0x44,1) ; // start conversion return result ;

}
// —————– end of readtemps() ——————-

By: mrspeed

mrspeed — Thu, 04 May 2023 18:40:45 +0000

In reply to Hans. link does not work

By: Sara Santos

Sara Santos — Thu, 27 Apr 2023 08:44:55 +0000

In reply to Viren.

Hi.
To display readings from all sensors in a web server you can take a look at our ESP-NOW Web Server project (it gathers and displays data from different boards): https://randomnerdtutorials.com/esp-now-auto-pairing-esp32-esp8266/
For logging all data in excel, we have this tutorial: https://randomnerdtutorials.com/esp32-esp8266-publish-sensor-readings-to-google-sheets/
For other data logging solutions, we have this compilation: https://randomnerdtutorials.com/esp32-how-to-log-data/
Regards,
Sara

By: Viren

Viren — Wed, 26 Apr 2023 00:53:12 +0000

Hi,
I am looking for a solution to monitor / log temperature data of all the cooling devices in my departmental store / supermarket which has about 30 fridges & freezers distributed in ~150 sqmtr area. I want to use One wire sensors (DS18B20) network of clusters, i.e. max 4 to 5 sensors in a cluster physicall connected with an ESP board, and about 5 different clusters (ESP Boards) further connected wireless (either using Wifi or ESP NOW) with the ESP or Arduino Board (could be ESP32, NodeMCU or Arduino UNO).. Hence want to keep a log of all the temperature sensors in an excel file as well as able to monitor the temperature on web server!

can you pls help me with this project as need some adv on how to design this solution!

thanks

By: jovo0911

jovo0911 — Mon, 17 Apr 2023 21:02:54 +0000

In reply to jovo0911.

reading and store the sensors is not the problem. Problem is if I change a sensor(damage) the sort order change. So I didn’t know where the sensor (there a 12) was.
i store sensor data in that way Sensor_1 –> DataDB

Sensor_1 = 00:00:00:00:00

so I know every time who is who.

By: jovo0911

jovo0911 — Mon, 17 Apr 2023 07:29:29 +0000

Hi,
I search a way to store sensor address in EEPROM. Need this for exactly identify a sensor to store data in a DB. I store data order by sensor_name.

Any good ideas!

JoVo

By: Sara Santos

Sara Santos — Thu, 02 Mar 2023 18:46:05 +0000

In reply to Pavan.

Hi.
That usually means wrong connections and/or bad signal due to very long cables.
Regards,
Sara

By: Pavan

Pavan — Thu, 02 Mar 2023 11:14:45 +0000

Output shows -127 why?

By: Sara Santos

Sara Santos — Mon, 27 Feb 2023 20:50:43 +0000

In reply to daniel lobo.

Olá.
Para isso tem criar differentes instâncias do sensor. Uma para cada pino.
Por exemplo, para o pino 4 criamos a instancia chamada ds:
OneWire ds(4); //data wire connected to GPIO 4
Se quisermos outro pino, por exemplo, GPIO2, temos de criar outra instancia, mas com um nome diferente. Por exemplo:
OneWire ds1(2);
Depois tem de fazer tudo igual, mas para as duas intancias.
Espero ter ajudado.
Cumprimentos.
Sara Santos