/diy/ - Do It Yourself

I'd like to interface some microcontrollers with a shared bus signal. The bus voltage level stays at +5V when idle and it can be pulled down to 0V by any bus device. Each bus device has an open-collector output for interfacing with the bus. I came up with this circuit to accomplish this function. Do you think it makes any sense? Is there any easier way to do this?

Q2 would sense the bus voltage level. If any device pulls the bus down to 0 V, Q3 turns on and outputs a logic "0" into PA0 input pin.

When the micro wants to pull down the bus, it activates Q1 by outputting a logic "1" into PA1 output pin.