Wireless Stick Lite no Connection to Arduinio

Hi,
If you pull up Pin2 (GPIO2) with 10k to 3.3V, Wireless Stick Lite won’t connect to arduino:

Connecting……_____…

If you leave Pin2 floating or pull it down to GND, arduino will connect immediately.
Interestingly, schematic doesn’t show any internal connections with Pin2.

I need this, because I must connect i2c to these pins, and i2c need a pull-up.
After programming, I can use Pin2 for i2c.
Tested with 433 and 868MHz Version, also the newest.

GPIO2 must also be either left unconnected/floating, or driven Low, in order to enter the serial bootloader.
In normal boot mode (GPIO0 high), GPIO2 is ignored.


The hardware I2C port should be 21 and 22

Thank you for the link - that explains it! The reasons for not choosing P21 are:

  • ) Someone had the bright idea to connect P21 to Vext control. So either Vext or SDA. I needed Vext.
  • ) GPIO2 and GPIO15 are hard wired to the ULP I2C controller. So if you want to monitor your sensors in ULP mode (https://github.com/wardjm/esp32-ulp-i2c), you must use GPIO2 for SCL, which then will be driven high.

One more consideration with I2C:
In theory I2C can be mapped to almost any Pin. However I found some ugly glitches / spikes in the I2C communication on some pins (also on GPIO2) which can even flip bits. This happens on LoRa32V2 with Pins 4 and 15, even though it is used for OLED I2C).