Max32 I2C and pull-up resistors

Created Sat, 19 Jul 2014 18:36:24 +0000 by mdsousa

mdsousa

Sat, 19 Jul 2014 18:36:24 +0000

Hi

I have my Max32 hooked up to Adafruits 16-channel 12-bit servo driver and the servo demos seem to work. I'm curious though if I need to add pull-up resistors? If so, do they go between the SCA/SCL pins and 5v?

Thanks...

majenko

Sat, 19 Jul 2014 19:10:43 +0000

If the board has no pullup resistors of its own then yes, you need to provide pullup resistors. They should go between the SCL/SDA lines and the 3.3V pin, not the 5V pin (the MAX32 is a 3.3V device - pulling it up to 5V could damage it).

mdsousa

Sun, 20 Jul 2014 15:48:26 +0000

They should go between the SCL/SDA lines and the 3.3V pin, not the 5V pin (the MAX32 is a 3.3V device - pulling it up to 5V could damage it).

Thanks for the response majenko. Even if the Servo brd (Adafruit 16-channel 12-bit pwm servo driver) takes 5v power from the Max32 external 5v connector the I2C lines should be pulled-up to 3.3v? I will do that. Any resistor values that are better than other values?

Thanks...

majenko

Sun, 20 Jul 2014 16:11:52 +0000

The resistors should be in the region of 3.3KΩ