Which wireless board?

If they are functionally the same, I don't care. I've never had a TTGO board arrive DOA, but I have one where the UART chip died after a bit. But at $5 each, it's a risk I am willing to take. I noticed that the last batch I bought had a blink program already loaded.

I have a couple of ESP32 boards, but never needed them when a D1 Mini would do the job.

Hi. I have ordered a WeMOS D1 Mini, I already have a BH1750 (LUX) a UVM30A (UV) and a BME 280 (Press, Temp & Hum). I notice form the Pinout Schematic, there is only one connection each for SDA & SCL pins, do I assume from this that you can create a bus bar to connect two devices together on the same pins?

The SCA and SCL lines are for the SPI bus.


there are countless people who can not get an ESP32 to take a program. you jump through all the hoops, you try every one of the countless tricks shown on countless web sites, and nothing happens. they are too small to use as skeet if they don't work.

if you ask about RF modules, tell us where you live. In the US we can legally use only 915 mhz and 2.4 ghz modules. many people get away with 433 mhz modules, but if you have multiple FCC licenses, you have to do it legally.

915 mhz modules require dramatically complex programming, leaving the NRF24L01 as the module of choice for a beginner.

You can only use 433 mHz devices if you are a licensed Amateur Radio Operator.
You are using RFID to scan containers:

FCC Part 15 rules:
ยง 15.240 Operation in the band 433.5โ€“ 434.5 MHz.
(a) Operation under the provisions of this section is restricted to devices that use radio frequency energy to identify the contents of commercial shipping containers. Operations must be limited to commercial and industrial areas such as ports, rail terminals and warehouses.

Part15 is secondary to Amateur Radio use.

(I am a Ham, by the way).

That said, there are millions of 433 mHz devices in use that makes 433.5 - 434.5 mHz useless for Amateur Radio purposes.

Hi SteveMann.

This did not really ask my question, I have read your recommendation, and it will not sink in to my weak brain, can I organ I not couple more than one i2c device on a remote bus, I have drawn a crude schematic in Powerpoint and uploaded it in PDF form, would you

weather station.pdf (296.3 KB)

As long as each device has a different I2C address, you can put all the devices on the bus that you want.

Check the specifications for the address, or connect them one at a time and run a sketch in the Adafruit libraries called i2c_address_detect. This will tell you what the device address is.

If you don't have the Adafruit library, go to the library manager and install it.

Sometimes the device lets you change the address with one or two jumpers. Again check the device specifications.

We would very much prefer a pencil and paper schematic over any pretty picture. (Fritzing is NOT a schematic).

I have a few of the ESP32 wide boards. the inner pins match that of the WEMOS D1 mini. the outter pins add ESP32 pins.

I also have a few larger boards, 30 pins and 34 pins,
different brands, have different pins brought out to different places.

When I make a PCB, I usually order 5 or 10. So unless I get the exact same pin-out the boards are useless.

I get boards that appear to be mass produced with the hope that if one supplier copies another, they board I do wind up with has the same pin-out.

I've only used the ESP32 on a couple of projects, much preferring the Wemos D1 Mini. Never had a clone that didn't have the same pinout as the original.


My WEMOS D1 MINI arrived today, I eagely opened the packet, and before I connect it to the Computers USB comport, I'll just check the voltage required to power the board, then confusion set in. I have read that the D1 MINI is 3.3 vdc, and can be programmed using the Arduino IDE, but the PC's voltage at the Com Port is 5 vdc, so how can I use the Arduino IDE if this is correct, will it not fry the DI MINI?

The operating voltage is 3V3, but it has a micro-USB connection, so you can obviously power it with 5V. Note if you are still nervous that the board has a 5V pin on it, which is presumably coming from the USB.

Look at the schematic.
The USB 5V pin goes into a 3.3V regulator. It operates at 3.3V which means your I/O is all 3.3V. So don't connect 5V devices to it without a level converter chip.

Many Thanks, you have kindly confirmed what I thought, I am just lacking a bit of confidence, in my own ability.