Can I interconnect all echo pins from multiple ultrasonic sensors?

Question

I want to use (probably) four ultrasonic sensors HC-SR04. These use a trigger pin and echo pin.

For the echo pins, I want to connect them to a timer with 'Combined Channels PWM Input on CH1', and the Input Trigger set to TI1FP1, so it is able to automatically time the high time of an echo.

However, since I don't want to use 4 timers, I want to interconnect all echo pins (and trigger the trigger pins of the sensors one by one).

Would this work, or is it not adviced to 'set' a signal to an echo pin when another echo pins becomes high?

Or should I use an IC with logical ORs? or is there a better/easier way?

^{simulate this circuit – Schematic created using CircuitLab}

I got it by someone and he doesn't know the source, so I don't have a datasheet, this is something similar: Information

Answer 1

No, those sensors use a TTL level output signal for echo, so you'll have use an or gate or diodes plus a resistor to implement an or gate. You can drive all the triggers with a single output, although you won't be able to tell which sensor each echo comes from and multiple echo pulses that overlap will appear as a single long pulse.

^{simulate this circuit – Schematic created using CircuitLab}

Answer 2

The Echo pin is a TTL output¹, according to the datasheet for the HC-SR04. Don't wire the Echo outputs together directly. If one output is in a high state and another output is in a low state and they are connected together, then one of the outputs can burn.
Instead, combine the outputs using an OR gate IC.

¹ _{If it were open-collector or an open-drain output, you could create a wired OR with a pull-up resistor.}