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Topic: i2c high speed and pull-up resistors (Read 67 times) previous topic - next topic

canilony123

hello guys i wanna ask about 2 things
first one is i'm connecting and arduino uno attached to a usb host sheild and transferring data of a mouse coordinates to 10 arduino leonardo
i'm using the standard speed 100
normal mode
my wires is all about 10 cm long
1) i need to speed up the comm to fast mode
how to make this ? and the line of code where to put it in the code and in the master or slave ?

2) what about the pull-up resistors ? does arduino uno includes built in pull-up resistors ? does it needs to disable it and put my own pull up resistors ?

Koepel

1.
Wire.setClock( 400000) after Wire.begin(). I'm not sure if the Slave does use it since the Master makes the SCL clock, but you can put it in the sketches of the Slaves anyway.

Does the MultiSpeed I2C Scanner work on the Leonardo ? https://github.com/RobTillaart/Arduino/tree/master/sketches/MultiSpeedI2CScanner.
That will give a good indication about how solid the I2C bus is.

2.
Every Arduino has a internal pullup resistors of 30k or 60k (I forgot what it was).
11 times 30k parallel is 2k7
11 times 60k parallel is 5k7
Both are fine with me, there is no need to add a extra pullup resistor.

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