Functionality of Direction Pin

[pilo1337]

Hi,

it seems that i dont have understood the functionality of the data direction pin.
i connected a MAX485 with RE&DE shorted together to the data direction pin. but i only get dmx out, no in.

what am i doing wrong?

[vanvught]

The H2+ ARM SoC has 3V3 GPIO pins. The pull-ups should be connected to 3V3 -> A quick fix could be removing all the pull-ups.

The MAX485 VCC should also be at 3V3. But that is not working according to the datasheet.

A level-shifter could be a better solution.

Or alternatively C428880

[pilo1337]

oof, never thought about the 3v3 gpio pins.. my mistake..
there will be a rs485 bus driver with 3v3 supply voltage, i change the board either to another driver or add a level shifter.

thank you!

[pilo1337]

can you tell me if this should work? i use the max3485 now, which is a 3v3 rs485 bus driver: https://www.mouser.de/datasheet/2/256/MAX3483E_MAX3491E-1291288.pdf