Let's Control It

Hi

for testing and general evalution I often use a Wemos Wroom 02 (https://oneguyoneblog.com/2018/12/28/we ... uino-ide/) which prodives power supply by battery and onboard OLED screen.
For this I used normal ESPeasy Mega releases as for my projects.
The OLED is connected by I2C on GPIO 4,5 but now I like to test a illumination sensor like BH1750 to check situation and measure at different locatlions. But the BH1750 is also connected via I2C BUS and I´m asking myself how to connect this additional device by using the OLED screen at the same time for showing the measurement results.

Can you give recommendation? Configuration of 2 I2C Bus interfaces is not foreseen by ESPEasy as I assume by the hardware settings and GPIO4,5 is not available for additional connections if I´m right.

Thanks and best regards!

I2C devices can be connected in parallel (SDA-SDA-SDA and SCL-SCL-SCL). There is only 1 exception: if 2 devices have the same 'address' they can't work together.
The BH1750 and OLed display have different addresses on the bus, so they can be used together without issues.

Thx Ath and the adress of the BH1750 sensor can be adjusted.

My question is more hardware related. Based on the Wemos Wroom Board I do not see any other chance than soldering additional connections directly to the esp8266 chip. I do not see any other chance to access GPIO 4,5 on it´s way to the directly connected OLED Display.

Like to double check or if you have any good idea to solve because i do not like to solder directly at the esp chip:

If the OLED display has accessible pins you can also solder some wires on the display pins.

Oetsch wrote: ↑28 Apr 2021, 16:00 My question is more hardware related. Based on the Wemos Wroom Board I do not see any other chance than soldering additional connections directly to the esp8266 chip. I do not see any other chance to access GPIO 4,5 on it´s way to the directly connected OLED Display.

Like to double check or if you have any good idea to solve because i do not like to solder directly at the esp chip:

That is one of the issues raised in the chat in the link you provided. There one of the solutions is to add another I2C bus using D3 and D4, but ESPEasy doesn't have provisions for that.

As the unit is pretty hard to repair, might something break, I wouldn't worry about soldering (close) to the ESP, it is just as vulnerable to the heat of the soldering tip (use a thin/sharp tip) as any chip, so just attaching a (thin) wire to 1 connection, and leaving some seconds to cool in between shouldn't be problematic or of high risk.

Maybe you can also add some hotglue on the wires to make sure they don't break off easily.

@TD-er @Ath

Big Thx!

No the wires/Pins of the OLED are not accessible. There is a flat ribbon cable but this would be more difficult to solder.

I´ll have a check if I can solder the ESP chip directly as you described but for the next test I´ll continously will have wifi access, so maybe just disable I2C at GPIO4,5 and use other GPIOs for the I2C BH1750 sensor and send results by MQTT.

But good to have confirmation about the understanding and in case of "very big fingers" during soldering .....the device isn´t so expensive ....let´s give it a try

Thx!

Oetsch wrote: ↑28 Apr 2021, 20:11 No the wires/Pins of the OLED are not accessible. There is a flat ribbon cable but this would be more difficult to solder.

That flat ribbon cable is the OLED-controller to display connection, nothing to do with I2C anymore.

Oetsch wrote: ↑28 Apr 2021, 20:11 I´ll have a check if I can solder the ESP chip directly as you described but for the next test I´ll continously will have wifi access, so maybe just disable I2C at GPIO4,5 and use other GPIOs for the I2C BH1750 sensor and send results by MQTT.

Using an extra ESP is also an option, but you can use the sensor on that unit, it is more than capable to handle both.
Switching to other GPIO pins for I2C will render the display inaccessible, so I'd still go for adding the wires, and a few spots of hot glue to fix them, to connect the BH1570, it's not that hard, just have a bit of confidence in yourself

Thx! Not my best work but for testing purpose it woks....

Great!