can not get BMP280 to work

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GravityRZ
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Posts: 107
Joined: 23 Dec 2019, 21:24

can not get BMP280 to work

#1 Post by GravityRZ » 14 Feb 2020, 18:43

i have a BMP280 connected to a Wemos D1 mini running latest ESPeasy mega software
i am using the BMX280 plugin

VCC on 3.3V
GND op GND
SCL op D1
SDA op D2
CSB 3.3V (to select i2C)
SD0 GND (to select 0x76 adres)

somehow i do net get any data in

hardware page is also on default
SDA GPIO-4 D2
SCL GPIO-5 D1

in the log it states
BMx280 unable to detect chip id


can anybody see what i might be doing wrong?

Domosapiens
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Joined: 06 Nov 2016, 13:45

Re: can not get BMP280 to work

#2 Post by Domosapiens » 14 Feb 2020, 22:40

Did you try:
Tools / I2C San ?
Did it discover the module ??
At 0x76 address ??
30+ ESP units for production and test. Ranging from control of heating equipment, flow sensing, floor temp sensing, energy calculation, floor thermostat, water usage, to an interactive "fun box" for my grandson. Mainly Wemos D1.

GravityRZ
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Posts: 107
Joined: 23 Dec 2019, 21:24

Re: can not get BMP280 to work

#3 Post by GravityRZ » 14 Feb 2020, 22:59

no it did not discover the module.

also i tried putting the module to 0x77 (connect SDO to 3.3v) but this did not help either.

really strange


tried other wemos module but the same result so the problem is either a faulty module or something i missed

TD-er
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Re: can not get BMP280 to work

#4 Post by TD-er » 14 Feb 2020, 23:48

Make sure the set pins for using I2C are the ones you try to use.
See the "Hardware" tab in the web interface.
It is best to use these:
- GPIO-4 (D2) for SDA
- GPIO-5 (D1) for SCL

Most BMP280/BME280 boards have no need to set them to I2C mode.
Make sure the board you're using is for 3v3. On AliExpress there are lots of batches sold for 5V only.

GravityRZ
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Posts: 107
Joined: 23 Dec 2019, 21:24

Re: can not get BMP280 to work

#5 Post by GravityRZ » 15 Feb 2020, 08:34

it is this one.
got it from opencircuits (expensive but fast shipping)

so you are saying VCC should be connected to 5V (on the site it states max 3.6v)
as far as i can tell there is no standard for VCC
bmp280.JPG
bmp280.JPG (38.06 KiB) Viewed 5267 times
Attachments
bmp280-2.JPG
bmp280-2.JPG (25.6 KiB) Viewed 5262 times

Shardan
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Joined: 03 Sep 2016, 23:27
Location: Bielefeld / Germany

Re: can not get BMP280 to work

#6 Post by Shardan » 15 Feb 2020, 10:41

If the picture shows the board you use exactly I won't use 5V.
I can't see any voltage regulator, just some capacitors and resistors.
Following datasheet the BMP280 has a max. Vcc of 3,6V!

For I²C the datasheet shows this circuit:
.
BMP280-I2C.jpg
BMP280-I2C.jpg (151.62 KiB) Viewed 5244 times
.
Many modules connect Vdd and Vddio internaly, that is usual and no problem.
(Yes, they call it Vdd instead of Vcc. Names.....)

So for the standard I²C address SDO should be connected to GND, for alternative address to Vcc.
For using I²C the CSB input should be connected to Vcc.

As I have no schematic of that module i can't see if inputs are pulled up or down with the
resistors so external connection might lead to a better result.

The full datasheet can be found here:
https://ae-bst.resource.bosch.com/media ... -DS001.pdf
Regards
Shardan

GravityRZ
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Posts: 107
Joined: 23 Dec 2019, 21:24

Re: can not get BMP280 to work

#7 Post by GravityRZ » 15 Feb 2020, 10:53

thanks

i am going to inspect the module under a magnifying glass because it is hooked up exactly like you said.

i even changed address to 0x77 to make sure there is not a bug in the plugin which defaults to that(both 0x76 and 0x77 do not work)

if i bought this one at aliexpress i could live with that but i paid EUR 3,50 ex shipping so for that price i really need it to work

GravityRZ
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Posts: 107
Joined: 23 Dec 2019, 21:24

Re: can not get BMP280 to work

#8 Post by GravityRZ » 15 Feb 2020, 13:07

got it working.
i noticed a connection which was not 100% ok
under a microscope i was able to do some soldering on the pcb.

also once i got it working i tested by removing the SDO and CSB connection, still working and defaults to I2C and 0x76
thanks for the help

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