Hey there,
Setting up my heating system with ESP32 and home assistant. For developping purposes, I had all my temperature sensors ds18b20 connected in star configuration with 1m cable each and a pullup resistor of 4.7k. Working perfectly.
Now setting the system in real conditions, I placed one sensor at 25m from the board. After some troubles because of cable capacitance or something like that, I ended up with a working configuration by using a dedicated pin on ESP for this particular sensor, a 2.2k resistor and a little 100nF capacitor at the end of the twisted pair cables. Now the data from this sensor is accurate and stable but … my ESP32 cannot boot. To make it work, I have to unplug the 2.2k resistor, boot the board, then plug the resistor.
Here is the summary :
- 5 sensors with 4.7k pullup, normal mode, star wiring 1m stubs, are connected to GPIO 21, works fine, and boot fine.
- 1 sensor with 2.2k pullup, normal mode, connected to GPIO 27, works fine, can’t boot unless the resistor is unplugged.
Tried to change GPIO, to boot with only with the single sensor … Nothing.
What am I missing out ?
Thank you