Need help with an ultrasonic sensor interface circuit to ev3

In summary, the conversation involves building a robot using Lego Mindstorm with an ev3 brick that will follow a pre-determined path and maintain a distance behind another robot. The ev3 will be connected to 2 DC motors, 3 light sensors, and an ultrasonic sensor. The person is seeking help with building an interface circuit for the ultrasonic sensor and has completed the trigger circuit using a 555 timer. They are looking for ideas on how to convert the echo output of the sensor to be readable for the ev3 brick and considering using an average value or creating a trigger signal. They also mention the need to keep in mind the speed of sound and the sampling rate of the ev3 processor. Available lab circuit elements include capacitors
  • #1
btpolk
38
0
I'm currently building a robot using Lego Mindstorm with an ev3 brick that will follow a pre-determined path (marked by black tape), maintain a certain distance behind another robot, and coming to a stop at the end of its journey. The ev3 will be connected to 2 DC motors, 3 light sensors, and an ultrasonic sensor.

The specifics of the test are irrelevant because I just need some help with build an interface circuit for the ultrasonic sensor (SRF04). I have the trigger circuit completed. I'm using a 555 timer in a-stable operation with parameters: Rb = 220 kOhms Ra = 1 kOhms C = 0.1 uF. Parameters are defined by the TI document (http://www.ti.com/lit/ds/symlink/ne555.pdf) on page 11. This gives me a period of about 31ms and duty cycle of about 50%. Now I need to convert the echo output of the sensor to be readable for the ev3 brick. I was thinking average value but I'm not sure if that's correct or how to go about it. Any ideas?

Available lab circuit elements: capacitors, resistors, op-amps, 555 timers, voltage regulators, and diodes.
 
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  • #2
Sound travels at 1ms per foot, so you need to be able to sense the reflection delay with that in mind. The ev3 only samples at 1000Kz, so you will need some external circuit. You can create a voltage that is proportional to the echo return time.

Or, possibly you can create a trigger signal that interrupts the processor and have it figure out the delay.
 

1. What is an ultrasonic sensor?

An ultrasonic sensor is a device that uses high-frequency sound waves to detect the distance and presence of objects. It emits sound waves and measures the time it takes for the waves to bounce back, allowing it to calculate the distance to the object.

2. How does an ultrasonic sensor interface with an EV3?

An ultrasonic sensor can interface with an EV3 by connecting the sensor's output pin to one of the EV3's input ports. The sensor can then be programmed using the EV3 software to read and process the data from the sensor.

3. What is the purpose of an ultrasonic sensor interface circuit?

The purpose of an ultrasonic sensor interface circuit is to ensure that the electrical signals from the sensor are compatible with the EV3's input ports. The circuit may also include components such as resistors and capacitors to regulate and filter the signals.

4. Can an ultrasonic sensor interface circuit be built using basic electronic components?

Yes, an ultrasonic sensor interface circuit can be built using basic electronic components such as resistors, capacitors, and transistors. However, it is recommended to use a pre-made sensor interface circuit to ensure proper functionality and compatibility.

5. Are there any troubleshooting tips for an ultrasonic sensor interface circuit?

If the ultrasonic sensor interface circuit is not working properly, it is important to check all connections and make sure the circuit is properly assembled. It is also recommended to refer to the manufacturer's instructions or seek assistance from an experienced individual. Additionally, using a multimeter to check for proper voltage and signal levels can help identify any issues with the circuit.

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