DS18b20 Using Multiple Devices on the same bus

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#DS18b20 Using Multiple Devices on the same bus

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Tyrone Smith 08/20/2024 06:54 AM

I'm trying to use multiple DS18b20 temperature sensors:

import gpio // Sensors
import ds18b20 show Ds18b20 // Temperatursensor


GPIO-PIN-NUM1 ::= 2 // Outside Temperature GPIO
GPIO-PIN-NUM2 ::= 5 // Inside top Temperature GPIO

main:
  temp1 := gpio.Pin GPIO-PIN-NUM1 --input --pull-up=true //Temperature-sensor Outside
  ds1 := Ds18b20 temp1
  temp2 := gpio.Pin GPIO-PIN-NUM2 --input --pull-up=true //Temperature-sensor Outside
  ds2 := Ds18b20 temp2


  temperatur1 := ds1.read-temperature // Outside
  temperatur2 := ds2.read-temperature // Inside top

  print "Temperatur 1: $temperatur1"
  print "Temperatur 2: $temperatur2"

I found this comment in the ds18b20.toit lib but i honestly don't know how to make use of it.

Assumes there is only one sensor connected to the given $pin.
  If there are multiple sensors, then the driver misbehaves. In that
    case use $(Ds18b20.constructor --id --bus) instead.

(edited)

OPTyrone Smith

I'm trying to use multiple DS18b20 temperature sensors: ``` import gpio // Sensors import ds18b20 show Ds18b20 // Temperatursensor GPIO-PIN-NUM1 ::= 2 // Outside Temperature GPI...(edited)

floitsch 08/20/2024 07:06 AM

Given that you use two different pins, the sensors aren't on the same bus.

floitsch 08/20/2024 07:10 AM

If you want to use several ds18b20 on the same bus, then you would do a bus scan first.
Something like this: https://github.com/toitware/toit-ds18b20/blob/3bc3a4b3fa21dd7558cc53680aadae7f9ee9452c/examples/multi_bus.toit#L24

toit-ds18b20/examples/multi_bus.toit at 3bc3a4b3fa21dd7558cc53680aa...

Contribute to toitware/toit-ds18b20 development by creating an account on GitHub.

Tyrone Smith 08/20/2024 07:10 AM

If I want to use my approach, how can I fix this error?

floitsch 08/20/2024 07:11 AM

On a standard esp32?

Tyrone Smith 08/20/2024 07:12 AM

Yes

floitsch 08/20/2024 07:13 AM

Esp32s3 or esp32?

Tyrone Smith 08/20/2024 07:14 AM

casual esp32

floitsch 08/20/2024 07:24 AM

The one-wire protocol (used by the ds18b20) uses the RMT peripheral underneath. There is only a limited number of them available on the device (4 iirc).
I thought that 1-wire takes two for each bus, but maybe it needs more. I will check later when I have a device at hand.

Tyrone Smith 08/20/2024 07:24 AM

Okay, thank you!
lmk as soon as you have any updates

floitsch 08/20/2024 08:26 AM

I can not reproduce so far.

floitsch 08/20/2024 08:27 AM

Do you have any other program running that could use the RMT?

floitsch 08/20/2024 08:27 AM

Wait

floitsch

Do you have any other program running that could use the RMT?

Tyrone Smith 08/20/2024 08:31 AM

No, just the casual jaguar container is running

floitsch 08/20/2024 08:31 AM

I can reproduce now. Was just a user error... Investigating

Tyrone Smith 08/20/2024 08:32 AM

Thanks a lot!

floitsch 08/20/2024 08:32 AM

While I'm looking: in the worst case you can just allocate and close the device inside the loop.

floitsch 08/20/2024 08:33 AM

A bit heavier, but that would definitely allow you to read the two sensors.

Tyrone Smith 08/20/2024 08:38 AM

import gpio // Sensors
import ds18b20 show Ds18b20 // Temperatursensor


GPIO-PIN-NUM1 ::= 2 // Outside Temperature GPIO
GPIO-PIN-NUM2 ::= 5 // Inside top Temperature GPIO

main:
  temp1 := gpio.Pin GPIO-PIN-NUM1 --input --pull-up=true //Temperature-sensor Outside
  ds1 := Ds18b20 temp1
  temperatur1 := ds1.read-temperature // Outside
  print "Temperatur 1: $temperatur1"
  ds1.close
  temp1.close

  temp2 := gpio.Pin GPIO-PIN-NUM2 --input --pull-up=true //Temperature-sensor Outside
  ds2 := Ds18b20 temp2
  temperatur2 := ds2.read-temperature // Inside top
  print "Temperatur 2: $temperatur2"
  ds2.close
  temp2.close

It works perfectly fine like this:

floitsch 08/20/2024 08:38 AM

Exactly. But I'm still investigating why two buses aren't supported. My gut feeling was that two were fine and there weren't.

Tyrone Smith 08/20/2024 08:39 AM

Okay, I'll just go with that solution for now, if you get the other one to work aswell i would prefer that.
Thank you for your help

floitsch 08/20/2024 08:47 AM

Found it. It's a regression with recent releases. (A one character typo...).
The next (or maybe the one after) release will have this fixed.

Tyrone Smith 08/20/2024 08:49 AM

Thank you for your support!

floitsch 08/20/2024 08:51 AM

Thank you for letting us know. The bug could have lingered for a while without your report.

24 messages in total