Do I need external pull up resistors for I2c communication?
Thanks!
It looks like you do.
There does need to be one (and only one) pullup resistor on each of the two I2C signals. Depending on which GHI board you’re using, they may already be installed. You can find out by looking at the schematic under the resources tab on the GHI web page for your board. For example, the Raptor already has them installed. In they are installed, you need to make sure none of the other devices you hang on the I2C bus have pullup installed and remove them if they do. If you have a lot of loads on your I2C bus, you may need to resize the pullups. There are a bunch of good article on the web about how to properly size the pullups for an I2C bus. Here’s one http://www.edn.com/design/analog/4371297/Design-calculations-for-robust-I2C-communications
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@ Gene -
I know that resistors are needed, I’m just not sure if there are resistors already on board (I assume not because I’m using through hole board) also I don’t know if the resisters can be configured through pin configuration as when you create reference to the pin, but I assume that it works different for i2c ports.
@ EvoMotors - As I said, I don’t see pull-up resistors on the board based on the schematics GHI provides. But you can always double check it with a DMM. You cannot control/set internal pull-ups when you use hardware I2C.
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