Ds1820 nd bidirectional level shifter

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Ds1820 nd bidirectional level shifter

By hakha4
- Tue Feb 28, 2017 11:12 am #63141 I have an ESP01 connected to 6 DS1820 sensors working fine but to get it work I had to use a strong pullup with a 680 ohm resistor from trial and error. The problem is that I need another sensor but I can't make it to work no matter what pullup resistor used. If hooked up with and Arduino at 5v no problem with 7 sensors. The cables are relatively short cat 5 so this shouldn't be the problem. The sensors are in parasitic mode and built in in heater tanks so not easy to change to power mode. I gather the main problem is that the ESP can't produce enough current to the sensors.

Has anyone tried to use a bidirectional level shifter like (http://www.ebay.com/itm/5pcs-2-CH-I2C-I ... 33a574d287)?
If this isn't impossible on what side should the pullup be,3.3v or 5v side ?
Any help appreciated
Regards Håkan
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Re: Ds1820 nd bidirectional level shifter

By piersfinlayson
- Wed Mar 01, 2017 4:46 am #63172
hakha4 wrote:I have an ESP01 connected to 6 DS1820 sensors working fine but to get it work I had to use a strong pullup with a 680 ohm resistor from trial and error. The problem is that I need another sensor but I can't make it to work no matter what pullup resistor used. If hooked up with and Arduino at 5v no problem with 7 sensors. The cables are relatively short cat 5 so this shouldn't be the problem. The sensors are in parasitic mode and built in in heater tanks so not easy to change to power mode. I gather the main problem is that the ESP can't produce enough current to the sensors.

Has anyone tried to use a bidirectional level shifter like (http://www.ebay.com/itm/5pcs-2-CH-I2C-I ... 33a574d287)?
If this isn't impossible on what side should the pullup be,3.3v or 5v side ?
Any help appreciated
Regards Håkan


Probably not very helpful given what you've said, but I've had no problems running 8 DS18B20s in power mode (powered by 3.3V), with a very weak pull up (the ESP8266's built in pull-up was just fine!).
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Re: Ds1820 nd bidirectional level shifter

By piersfinlayson
- Wed Mar 01, 2017 3:28 pm #63199
hakha4 wrote:Maybe the parasite mode is the main issue. BTW what library for Ds1820 are you using?


I think I did try parasitic mode a while ago but had no success.

I've based my code on some from here: https://github.com/nekromant/esp8266-frankenstein

Which in turn was based on: http://www.pjrc.com/teensy/td_libs_OneWire.html

My code is here: https://github.com/piersfinlayson/otb-i ... _ds18b20.c
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