I am writing because I would like to use the JSN - SR04T (a waterproof version of the ultrasonic range finder), in a bistatic way.
Let me explain, I have two sensors and I would like to use one of them in transmission and the other one in reception, with two different Arduino boards. I don’t need to evaluate the distance between the two sensors or any other parameters, I just want to blink a led if the Rx sensor receives a US pulse from the Tx sensor.
In my previous post I mentioned the NewPing Library, I have modified it because it is not a NewPing issue.
From what I have “studied” on line, I understood that it is quite impossible to do it in an easy way because the sensor is practically a range finder and it cannot be driven as a TxRx module. If I am right, from the Arduino board you can only read and write the echo and trigger pin of the sensor. When Arduino gives 5V on the trigger pin, the sensor will wait 10 us and then send the US pulse, while putting “high” the echo pin input to Arduino, until it receives an echo back. By the measurement of the time of “high” of the echo pin, we can evaluate the delay and so, the distance of the first obstacle.
So, if the RX sensor is not “woke up” on the trigger pin, it will never put high the echo pin and I will never know if it will receive an echo form any sensor, am I right?
By the way I am struggling to find a solution, by making use of two possible way out:
- A “fake” trigger on the RX sensor
- Force the Echo pin to HIGH directly from Arduino and wait for the senor to put it back to low, even if it has never sent a pulse
For solution#1 I mean the following:
Put the RX-US sensor in front of an obstacle so far that it will never receive any echo back (i.e. Y = inf in the attached figure)
Trigger the pin of the RX sensor (with no TIMEOUT on the echo pin) and wait for few seconds (checking that no echo bounced back has been received)
Trigger the pin of the TX sensor (in front of the RX sensor), with 5V
Wait for the echo pin of the RX sensor to fall down when it receives the pulse from the TX sensor
Put the echo pin of the RX sensor HIGH by Arduino
Trigger the pin of the TX sensor in front of the RX one
Wait for the echo pin of the RX sensor to fall down when it receives the echo from the TX sensor
For sure the second solution would be more useful and practical, but I don’t know if it could work (I don’t know the internal logic of the sensors)
Does anyone have any suggestion?
For instance, if I understood well the logic of the sensor and if solution 2, at least, is feasible.
Thank you in advance for any help.