ESP8266 Community Forum

- Sun Nov 19, 2017 9:46 pm #71954 I got the sensors last week and find that they work great! I have 2 questions that I didn't realize may be an issue with a second projaect.

1) how can I use more than 2 sensors?
2) how can I use these at a long distance?

I have a project that uses an UNO and 3 DHT11 modules. It works fine as is, but I want to replace it with a Wemos D1 and 3 BME280. The project is an attic fan controller. It monitors temperasure and humidity of 2 attic spaces and outside turning the fans on and off depending on conditions. It does not communicate with my home automation setup and the DHT11 are inaccurate. But, BME280 can only have 2 addresses on I2C and the technically can only be 10cm away from the board. My BME280 are both SPI and I2C.

- Tue Nov 21, 2017 3:04 pm #71987 I understand that I could use SPI for this, thought the range could be an issue. I'll probably mock something up with Cat5 to see if range is an issue. If so, I'll switch to using 2 NodeMCU boards I guess. It won't work nearly as clean though as logic will end up being remote for switching the fans.

- Sun Nov 26, 2017 11:59 pm #72098 Ok, I think I've confirmed that even though the spec says 10cm range for I2C, I can get significantly further range. I connected a Wemos D1 and a BME280 to a breadboard with a couple cat5 keystones. I was able to get 100% valid response from the BME280 with 6', 15', and 50' patch cables.

This is fine, but I need 3 sensors running concurrently. Since I can only use 2 BME280 on I2C due to address limitations, I'd like to try SPI. Unfortunately, I've yet to get SPI to work on the Wemos. If anyone could provide a link to some working code, I'd be grateful! I thought it would be a simple matter of changing the commented line for I2C to SPI, but that hasn't worked.

You do not have the required permissions to view the files attached to this post.

- Mon Nov 27, 2017 12:37 pm #72105 Use two I2C buses. Call Wire.begin() when you need to switch buses.