I tried both modes, parasitic and with + - and signal connected but I cannot get it to work.
The i2c board and sensor (bme280) get detected. I connect dit to the sda pin (a4) on an uno r3 clone. If I connect it directly to A3 it reads fine.
I tried with and without a pullup. (+- 5.2k according to my multimeter) and with 3.3 and 5 volt.
It is all not super important but it would be nice to beable to add those sensors to one of the i2c wires.
I just like the super cheap esp-01 boards. They are about 80 cents a piece and have way more memory but only 2 gpio pins. You an also use rx and tx but it is nice to beable to debug using serial. So I thought/was hoping that adding a digital io extender(s) (PCF8574) to get digital IO pins and 1 or more analog ADC's (ADS1115) I get as many IO ports and I want.
But it seems that it is not easy (or possible) to get them to work with existing libraries for the many common sensors/break out boards out there.
I guess I should focus on using i2c modules only.
Ps I am testing on an uno r3 clone first. Once I get it working there I try it on the esp8266