DS18B20 Sensor Detection via ONE-WIRE (1-Wire) Protocol

[Emanuele78]

Hi, where can I find a working One-Wire protocol? Is there an example provided by STM? I wrote code for a program to detect the temperature from a DS18B20 sensor, but I can’t detect the sensor, even though the debug shows everything is fine. Can someone help me? Thanks

[nimaltd]

Hi. I released new one wire library. It is non-blocking and can run on any pins.

Https://github.com/nimaltd/ow

[Andrew Neil]

EDIT: Oops - I missed that this is an old post (nearly a year), which has just been woken up by @nimaltd

So all of this has pretty much been said already:

First call should always be to see what the manufacturer says:

Choosing the Right 1-Wire Master for the Embedded Applications

Application Note 148: Guidelines for Reliable Long Line 1-Wire^® Networks

There is basic, MCU-independent code here:

Interfacing the DS18X20/DS1822 1-Wire® Temperature Sensor in a Microcontroller Environment

See also:

https://community.st.com/t5/stm32-mcus-embedded-software/ds18b20-sensor-detection-via-one-wire-1-wire-protocol/m-p/729945/highlight/true#M55860

---

@Emanuele78 wrote:

even though the debug shows everything is fine.

---

Clearly everything is not fine - it doesn't work!

A software debugger probably won't show hardware problems.

Are you sure that the DS18B20 actually works?

Is it wired correctly?

Please show your schematics; some good, clear photos of your setup may also help - see:

How to write your question to maximize your chances to find a solution

Have you used an oscilloscope to see what's actually happening on the wire?

The DS18B20 datasheet & links above show what you should be seeing...

Note that DS18B20 are commonly faked - are you sure you have a genuine one?

Does it work with any other controller; eg, Arduino?

See:

https://community.st.com/t5/others-stm32-mcus-related/ds18b20-one-works-one-doesn-t-on-stm32l071-both-ok-on-arduino/m-p/833866/highlight/true#M7818

---

@Emanuele78 Are you still there? Did you fix this?

[nimaltd]

Yes :) @Andrew Neil 

Because I released a library. It is non-blocking and very simple. And ready to use. I tested with 2 ds18b20 on bus and works perfectly. 

[Andrew Neil]

Just to collect together some more 1-Wire^TM tips:

1. Although the timing within a bit frame is critical, the timing between bits is not.
   So a blocking implementation only really needs to block for each bit - not the whole transaction.
   This also helps debugging - you can still breakpoint between bits.
   
   
2. UART and SPI can be used to "synthesise" the timing.
   See, for example: Using a UART to Implement a 1-Wire Bus Master
   discussed here: Dallas iButton and UART.
   
   

#1WireTips