MPL3115A2 wiring | KiCad EDA | Page 1

wicked rain Jun 5, 2024, 4:20 AM

#

Hello. I'm making a pcb for a low powered rocket. Its based off an ESP32. I'm using I2C to talk to a MPL3115A2 (altitude and temp sensor) but I'm not sure I wired it propery. Also, I'm pretty new to I2C protocols and wiring, so please be patient with me as I am only trying to understand.

#

I just copied the sematic of the Adafruit dev board, but I don't know if I need all that...

cunning kite Jun 5, 2024, 5:26 AM

#

Wtf is going on

#

Their schematics must be very funky

#

For I2C you only need two pullups, one on each line

#

The lower the resistance is, the faster you can use the bus but the higher the current consumption is

#

4K7 should be just fine

wicked rain Jun 5, 2024, 1:40 PM

#

@cunning kite so I should get rid of R15 4K7, what about the MIC522-33, I think think I really need that as I can get 3.3 v from the main stepdown

#

cunning kite Jun 5, 2024, 1:42 PM

#

wicked rain <@389422858452992012> so I should get rid of R15 4K7, what about the MIC522-33, ...

No, you need one pull up per line

#

As for the weird MOSFET contraption I don't know what it's doing

#

I was about to say it was a logic level shifter, but you're pullin up I2C lines with 3V3 while pulling up with 5V on the same side

wicked rain Jun 5, 2024, 3:45 PM

#

Can you send me an example of what it should look like ?

#

I’m fairly new to pcb design

cunning kite Jun 5, 2024, 4:01 PM

#

can you send what you were copying

wicked rain Jun 6, 2024, 12:35 AM

#

wicked rain Jun 6, 2024, 1:40 PM

#

@cunning kite

wicked rain Jun 6, 2024, 9:32 PM

#

@cunning kite can you help me?

cunning kite Jun 7, 2024, 5:16 AM

#

Look on each sides of the MOSFETs

#

It's a logic level shifter I think,which means that it transforms the tension of a logic signal

#

It's maybe because the altitude sensor does not accept signals higher that 3V3, and a regular Arduino uses 5V, however ESP32s only work with 3V3 so you shouldn't need this contraption in the middle of the I2C bus, you could technically wire it directly to the sensor

wicked rain Jun 7, 2024, 5:25 AM

#

Oh ok nice

#

I’ll try that tomorrow and let you know how it goes

wicked rain Jun 7, 2024, 5:22 PM

#

@cunning kite what about this 😁

cunning kite Jun 7, 2024, 6:44 PM

#

looks better, make sure they are using 3V3 from the datasheet

wicked rain Jun 7, 2024, 7:25 PM

#

from what data sheet? @cunning kite

cunning kite Jun 7, 2024, 8:31 PM

#

sensor's dataheet

wicked rain Jun 7, 2024, 11:07 PM

#

@cunning kite I don't understand, can you expalin agian?

cunning kite Jun 8, 2024, 8:11 AM

#

nvm, I2C is open drain, uneless you exceed max device's voltage you're good to go

#MPL3115A2 wiring