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Topic: does anyone speak chiglish? ebay description makes no sense (Read 242 times) previous topic - next topic

steveh2112

can anyone decode this please
https://www.ebay.com/itm/New-BMP180-3-3V-5V-Replace-BMP085-Barometric-Pressure-Sensor-Board-Arduino-GY68/322515433312
3.3V/5V BMP180

Features:
VCC is 5V, the output of the high level 3.3V, can be 5V power supply, which has a voltage conversion chip, but 5v and 3.3v can only choose a power supply mode, select the 3.3v can not use 5v 5v can not be selected 3.3v

huh!!! sounds like trump wrote it.

i'd like to use this on a 5V UNO/NANO without a voltage conversion chip. does anyone think it will work on a 5V I2C bus?

thanks

Wawa

BMPxxx are 3.3volt devices, so I2C should be at that logic level.

I don't see the two required mosfets for 5<>3.3 level shifting on those boards.
What I see is a 5volt to 3.3volt regulator (5-pin chip).

So you can power them from 5volt (VCC pin), but you shouldn't connect them to a 5volt I2C bus.

If that module is the only thing you're going to connect to the Uno/Nano, then you can disable pull up to 5volt in the wire library. Or disable pull up just after the wire.begin() call.
Leo..

steveh2112

thanks, its not the only thing on the I2C bus, i have a MPU6050 5v also so that looks like a problem.

but i did find this
https://forums.adafruit.com/viewtopic.php?f=25&t=13722
its a i2c master program that i think i can use 2 other analog i/o like say 2 and 3 (MPU uses 4 and 5) and i guess use a 3.3V pullup on that


Wawa

The MPU6050 is AFAIK also a 3.3volt device. Same story as the BMPxxx.
Can't tell if it's a problem until you post the a link, or clear pictures of both sides of that board.
Leo..

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