Forum Post: RE: Turning on the User LEDs on the AM335x EVM

Hi,

I've sperimented the same situation so I've read the datasheet for the I2C expander. The command 0x03 isn't for control the output, it's for configure the pin as input or output. So for correct use:

1) Configure expander's pin as output

i2cset -y 2 0x20 0x03 0x00

3) Set the pin that you want:

ex. i2cset -y 2 0x20 0x01 0x00 -> all the leds are off

       i2cset -y 2 0x20 0x01 0x10 -> D1 on

       i2cset -y 2 0x20 0x01 0x20 -> D2 on

And so on.