[time-nuts] BME280 board.

[Dan Kemppainen]

Hi All,

So it appears several of you have played with the BME280 chip. (Posts 
below...)

A while back I started a project with the BME280 that I didn't around to 
finishing. Basically, A BME280, PIC24, and Serial to USB cable.

The idea WAS to build a temp/pressure/humidity logger for time nuts use. 
There's an on board 32Khz crystal, and a few pins intended for PPS input 
or similar. The idea was to use a PPS (Or the RTC, or what ever) to 
trigger a sample (or every 5 or 10, or any number of PPS's (or 
seconds)), and send it up the serial port for logging.

Anyway, I did layout a board and populated three of them, but ran short 
of time to get much done with the code. It's been shelved ever since then.

If anyone on the list is interested in collaborating on such a project, 
let me know. I've got an extra board populated for anyone interested in 
helping on the project.

Dan


On 10/9/2019 12:00 PM, time-nuts-request at lists.febo.com wrote:
> ------------------------------
> From: Adrian Godwin<artgodwin at gmail.com>
> 
> Jim mentions the LM34 for sensitivity and LM34 or LM35 for cost compared
> with the DS1620. But also look at the BME280 : it has digital measurement
> of temperature with 0.01C resolution (50 times better than the DS1620),
> costs ?5 on digikey but less mounted on a breakout from ebay, and also
> measures pressure. The very similar BME280 also measures humidity.
> 
> ------------------------------
> From: Didier Juges<shalimr9 at gmail.com>
> 
> The BME series requires a fair amount of code to convert data from the
> sensor into human readable data like degrees. I use the BME280 in some
> applications.
> 
> Personally, for just temperature sensing, I found good old fashion
> thermistors to be cheaper and more accurate than most silicon sensors while
> requiring a single precision resistor and one ADC channel. When used with a
> 12 bit ADC, they offer excellent resolution around a relatively small
> temperature range, (progressively degrading resolution as you go away from
> the optimum temperature) which is ideal for an oven controller. They are
> also easy to use in noisy environments.
> 
> Didier KO4BB
> 
> ------------------------------
> From: Mark Sims<holrum at hotmail.com>
> 
> The BME280 does temperature, humidity, and pressure.  They are very nice.  Beware of BME280 boards sold on Ebay, etc.  A lot of sellers ship BMP280s.   One way to tell is the BME280 is in a square package and the BMP280 is more rectangular.
> 
> Also be aware that some BMP/BME280 libraries seem to have some error in their humidity calculation code and produce incorrect results.
> 
> ------------------