Two Cores, One SD

I’m going to have to look at this in just a minute but if what you are saying is true then we are in business! :smiley:

@philipq, reading the PR I see that even though @mumblepins’ “fix” seems to work, he and @mdma are not quite sure why. That is not exactly a fix is it?

@peekay123 I’m bouncing around replies here , sorry bout posting so much :)’

I’ve looked into I2C and 99% have a system in place to do as I described in my original post, but now with I2C. I have my WiFi core as the slave and the SD logging and data gathering Core as the master.

Two question!

Do I need pull up resistors of 10k on D0 and D1 then each going to +5V /+3.3V ?
Do I need this for each Core or just the master?

EDIT: I indeed need pull-ups on my 5V line, sorry for wasting time :)’’

@UST, if you are connecting two Cores then you only need one set of pull-up resistors on the I2C bus, both going to 3.3V.

The pull-ups are required because I2C uses open collector type of output where it will drive the pin to GND but float otherwise. This makes sense since multiple devices would “collide” on the I2C bus with one driving the data HIGH while another driving it LOW. :smile:

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