I2C Device not Detected from Cold Start

[changstrom]

Hi - I’m trying to read from a PMSA003I air quality sensor over I2C which is connected and powered from an ESP 32.

When I start the ESP from no power, I get a message saying no I2C devices are found.

But if I 1) re-flash the firmware OR 2) reset the ESP, it finds the I2C device.

In both of the later two cases, power is maintained to the sensor while the ESP restarts. This leads me to think the I2C chip on the sensor isn’t starting up fast enough to be ready when the ESP looks for it, and then it doesn’t try again after nothing is found.

I also don’t get any luck setting I2C scanning to False and specifying the address of the I2C device directly.

Is there any way to delay the I2C polling for a bit when starting up?

[nickrout]

Look at on_boot priorities.

[Mahko_Mahko]

You can try it at a sensor level too like this.

Is there some way to delay setting up a sensor, is that setup_priority?

I was curious about this and searched the ESPHome Discord for it. It seems some people are using it like this: sensor: - platform: am2320 setup_priority: -100 address: 0x5C temperature: name: "temp02" humidity: name: "humi02" update_interval: 60s I couldn’t find anything on a quick docs check.

And then you could try this too…

I2C bus scan after deep sleep recovery

I found the working config: on_boot: priority: 600 then: - lambda: |- Wire.begin(); delay(100); It was important to set the priority at 600 (the power up of the enabling pins had a highest priority).

[changstrom]

Setting the setup_priority to -100 seemed to do the trick to keep this from hanging. The logs still show no I2C device is found but the results from the sensor eventually appear, unlike if that parameter isn’t specified.