I2c distance measurement

I2c distance measurement

This depends on the load of the bus and the speed you run at. In typical applications, the length is a few meters ft. Another thing to be taken into account is the amount of noise picked up by long cabling. This noise can disturb the signal transmitted over the bus so badly that it becomes unreadable.

i2c distance measurement

The length can be increased significantly by running at a lower clock frequency. One particular application - clocked at about Hz - had a bus length of about m ft. If you need to go far at high speed, you can use an active current source instead of a simple pull-up resistor.

Philips has a standalone product for this purpose. Using a charge pump also reduces "ghost signals" caused by reflections at the end of the bus lines.

Yes indeed this exists. Philips manufactures a special chip to buffer the bi-directional lines of the I2C bus. Typically, this is a current amplifier. That way you can overcome the capacitance of long wiring. However, you will need this component on both sides of the line. The charge pump in this devices can deliver currents up to 30mA which is way too much for a normal I2C chip to handle.

With these buffers you can handle loads up to 2nF. The charge amplifier 'transforms' this load down to a pF load which is still acceptable by I2C components. Note: Since the speed of the I2C bus can be rather high, it is recommended to use a fast optocoupler. However, this circuit will not work on speeds higher then 10KHz. A 6N will do the job in all cases.

i2c distance measurement

How does it work? The problem with bi-directional lines is that a buffer tends to get stuck on a certain level. This case has been taken into account in the above schematic. In the following explanation we assume that the left side is transmitting and the right side is receiving the circuit is symmetrical Let's assume we send a logic 1 into the left side. The LED of the top optocoupler will stay dark. Since its transistor does not receive any light, it is not turned on.

The next transistor does not get driven and the line at the end is being pulled high via resistors 1' and 3'. The PNP transistor 5' will not get driven. Therefore the LED connected to it will not light up and there is no feedback signal.

Now let's see what will happen if we send a logic 0. The first transistor 5 will be turned on, therefore the led connected to it will start emitting light. This results in the fact that its matching transistor will turn on. The transistor connected to the emitter will be turned on also. The output line is now being pulled low via resistor 3'. This low level would turn on the PNP transistor, which would result in the other optocoupler to light, its transistor to turn on etc.

In other words, the circuit would go into a lock-up.

This way we have eliminated the deadlock.Two sensors for measuring distance with the Arduino are extremely popular: the infrared proximity sensor and the ultrasonic range finder. An infrared proximity sensor has a light source and a sensor. The light source bounces infrared light off objects and back to the sensor, and the time it takes the light to return is measured to indicate how far away an object is. An ultrasonic range finder fires out high frequency sound waves and listens for an echo when they hit a solid surface.

Distance Sensing Overview

By measuring the time that it takes a signal to bounce back, the ultrasonic range finder can determine the distance travelled. Infrared proximity sensors are not as accurate and have a much shorter range than ultrasonic range finders. Complexity: Both of these sensors are designed to be extremely easy to integrate with Arduino projects.

Again, the main complexity is housing them effectively. Infrared proximity sensors such as those made by Shape have useful screw holes on the outside of the body of the sensor. Maxbotix makes ultrasonic range finders that do not have these mounts, but their cylindrical shape makes them simple to mount in a surface by drilling a hole through. Where: A common application for these sensors is monitoring presence of a person or an object in a particular floor space, especially when a pressure pad would be too obvious or easy to avoid, or when a PIR sensor would measure too widely.

Using a proximity sensor lets you know where someone is in a straight line from that sensor, making it a very useful tool. IR proximity sensors are okay in dark environments but perform terribly in direct sunlight.

When using ultrasonic range finders, you can also choose how wide or narrow a beam you want. A large, teardrop-shaped sensor is perfect for detecting large objects moving in a general direction, whereas narrow beams are great for precision measurement.

The range finder needs some minor assembly. To use the range finder in your circuit, you either need to solder on header pins to use it on a breadboard, or solder on lengths of wire. You have three ways to connect your range finder: using analog, pulse width, or serial communication. In this example, you learn how to measure the pulse width and convert that to distance. The analog output can be read straight into your analog input pins but provide less accurate results than pulse width.

This example does not cover serial communication. Complete the circuit from the layout and circuit diagrams. The connections for the range finder are clearly marked on the underside of the PCB. The PW connection is the pulse width signal that will be read by pin 7 on your Arduino.

Measure distance (cm/inch) with ultrasonic module HC-SR04 using Arduino and LCD i2c

Make sure that your distance sensor is affixed to some sort of base pointed in the direction that you want to measure. You can find the MaxSonar code by Bruce Allen in the Arduino playground, along with some additional notes and functions. Create a new sketch, copy or type the code into it, and save it with a memorable name, such as myMaxSonar. Press the Compile button to check your code. The compiler highlights any grammatical errors, turning them red when they are discovered.

If the sketch compiles correctly, click Upload to send the sketch to your board. When it is done uploading, open the serial monitor and you should see the distance measured in inches and centimeters.

If the value is fluctuating, try using an object with a bigger surface. This sketch allows you to accurately measure distance in a straight line.

Distance Sensing Overview

Test this with a tape measure and make adjustments to the code if you find discrepancies. John Nussey is a designer, a technologist, and an entrepreneur who loves using technology in new and interesting ways. He has worked with Arduino for many years to prototype products and create interactive artwork. A proud Arduino advocate, he has taught the craft of physical computing and prototyping to people of all ages, competencies, and abilities.Basic principal of ultrasonic distance measurement is based on ECHO.

When sound waves are transmitted in environment then waves are return back to origin as ECHO after striking on the obstacle. The sensor module consists of ultrasonic transmitter, receiver and the control circuit. The module works on the natural phenomenon of ECHO of sound. A pulse is sent for about 10us to trigger the module. After which the module automatically sends 8 cycles of 40 KHz ultrasound signal and checks its echo. The signal after striking with an obstacle returns back and is captured by the receiver.

Thus the distance of the obstacle from the sensor is simply calculated by the formula given as. Here we have divided the product of speed and time by 2 because the time is the total time it took to reach the obstacle and return back. Thus the time to reach obstacle is just half the total time taken.

A 16x2 LCD is connected with arduino in 4-bit mode. And data pin D4-D7 is connected to 4, 5, 6 and 7 of arduino.

Find more about the working of distance measurement project in this tutorial: Distance measurement using ultrasonic sensor. In code we read time by using pulseIn pin. And then perform calculations and displayed result on 16x2 LCD by using appropriate functions. Can you give me a distance meter flow chart. I think you should read the arduino. Its Arduino Pro Mini, as mentioned in Components section.

Nobody can entered the this type of sms because sms is tool long. Tv On tv off on off like another message. You can connect to A6 and A7 but then define the Trigger and 'echo' pin accordingly.

I need one help to u am doing final year project please give some ideas harish. Well explained. Is there a significant difference?Add the following snippet to your HTML:. Project tutorial by Junez Riyaz. The ultrasonic sensor is consists of Transmitter and Receiver modules. Transmitter part ejects the pulse out and the receiver part receives the pulse. The time between transmission and reception is calculated. This data is processed to calculate distance. For more information check this link.

The basic principle of ultrasonic distance measurement is based on ECHO. When sound waves are transmitted in the environment then waves are returned back to the origin as ECHO after striking on the obstacle. Please log in or sign up to comment. I got my first Arduino recently, here I am gonna show you my first project which is Distance Measurement Using Ultrasonic sensors.

Project tutorial by mcharrison Project tutorial by MichDragstar. This project displays the readings of the ultrasonic sensor on LCD of your smartphone through 1Sheeld. Project tutorial by adam johns. It measures the distance between you and the place where you point it to.

Hope you'll enjoy it! It is a miniature counterpart of radio altimeter used on commercial aircrafts to be used with RC aircrafts and multirotors. Sign In. My dashboard Add project. Project tutorial. Schematic Download. Author Junez Riyaz 2 projects 2 followers Follow.

Respect project. Similar projects you might like. LCD display distance of an ultrasonic sensor Project tutorial by adam johns 8, views 0 comments 8 respects.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts.

It only takes a minute to sign up. Yes, I know that I2C is really designed for intra-board communication. I have been tasked with a "design goal" of using a common I2C bus for multiple I2C slaves to support a demo. For fast mode, and resistor pullup, capacitance should be less than pF, according to this NXP document I2C-bus specification and user manual.

Different assumptions will lead to different numbers. The insane sounding lengths like 10,25, and m are perfectly possible, and I use the method often with UART not I2C, but the method stands when I need to put stuff together quickly.

i2c distance measurement

It's not exactly the best way, though. The key is to know your input voltage threshold. Make sure the voltage drop in the ground lead is well below this, or else a transmitter at a high ground potential will not be able to pull the voltage low enough. Ideally, all devices will have their own wall wart and battery and no power will be sent over the ground wire between devices.

That limits speed to about 10kHz or so. I have heard that devices should have a resistor on SDL and SCK, because of the big capacitive load they are driving, of something like or ohms. But honestly, I2C is not at all the way to go for long distances. CAN transceivers or RS used with normal UART is a robust solution with very good fault protection, ESD resistance, speed, distance, etc, at a cost of a dollar a chip or so, ground offsets don't matter nearly as much so you are free to carry power along with data.

The only downside is that a can transceiver can reach 70ma transmitting and 1 or 2ma just listening, so I2C or direct TTL UART might be useful in extreme low power situations, but consider how much time you actually spend sending.

I work for a company making USB sensors. Most of them are based on I2C sensor chips, those devices can be split in two, so you can install the CPU part in one place and the sensor part in another.

At kHz, with a good error recovery protocol, 25m can be easily reached using basic wires. We were even able to reach m once with CAT5 cable.

Something like NXP's P82B96 could be used to change the voltage levels on the bus, allowing much longer distances. The datasheet contains examples for I2C cable lengths of 3m, 25m, m and m. IIC is a synchronous protocol, and as such, it can be run arbitrarily slowly to meet system requirements with respect to distance and noise. Sign up to join this community. The best answers are voted up and rise to the top.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up. Yes, I know that I2C is really designed for intra-board communication.

I have been tasked with a "design goal" of using a common I2C bus for multiple I2C slaves to support a demo. For fast mode, and resistor pullup, capacitance should be less than pF, according to this NXP document I2C-bus specification and user manual.

Different assumptions will lead to different numbers. The insane sounding lengths like 10,25, and m are perfectly possible, and I use the method often with UART not I2C, but the method stands when I need to put stuff together quickly. It's not exactly the best way, though. The key is to know your input voltage threshold.

Make sure the voltage drop in the ground lead is well below this, or else a transmitter at a high ground potential will not be able to pull the voltage low enough. Ideally, all devices will have their own wall wart and battery and no power will be sent over the ground wire between devices. That limits speed to about 10kHz or so. I have heard that devices should have a resistor on SDL and SCK, because of the big capacitive load they are driving, of something like or ohms.

How to Measure Distance with the Arduino

But honestly, I2C is not at all the way to go for long distances. CAN transceivers or RS used with normal UART is a robust solution with very good fault protection, ESD resistance, speed, distance, etc, at a cost of a dollar a chip or so, ground offsets don't matter nearly as much so you are free to carry power along with data.

The only downside is that a can transceiver can reach 70ma transmitting and 1 or 2ma just listening, so I2C or direct TTL UART might be useful in extreme low power situations, but consider how much time you actually spend sending.

I work for a company making USB sensors. Most of them are based on I2C sensor chips, those devices can be split in two, so you can install the CPU part in one place and the sensor part in another. At kHz, with a good error recovery protocol, 25m can be easily reached using basic wires. We were even able to reach m once with CAT5 cable. Something like NXP's P82B96 could be used to change the voltage levels on the bus, allowing much longer distances.

The datasheet contains examples for I2C cable lengths of 3m, 25m, m and m. IIC is a synchronous protocol, and as such, it can be run arbitrarily slowly to meet system requirements with respect to distance and noise. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Maximum I2C Bus Length?Pages: [1] 2. I2C Distance. I am creating a network with 1 master and around 10 slaves using I2C.

What can be the maximum distances between the Master and slave? I have read somewhere that distance is low. Is it true? Can distance be increased to say around 75m - m? Re: I2C Distance. The art of getting good answers lies in asking good questions. RS is not very compatible with i2c. There are some chips that split the signals and that would allow to be used but that's not very suitable for what you are doing IMO.

That would mean having a small processor at each sensor though. WillR Guest. This allows the designer to use I2C to interconnect equipment cabinets or for large area systems such as warehouse pick and place systems. The P82B96 and improved PCA use a static level offset on the slave side to isolate noise and loadings on either side of the device, allowing pF on the high drive side.

The nominal offset is 0. It also precludes operation with other bus buffers using special non-compliant I2C levels. You just need to use the search engines Thanks for the replies Man, I am in a pickle now. So I really have to change the protocol i used for this project? Anyone here who has worked with the i2c repeaters? We all make minor errors from time to time. Get over it. NXP is reputable and so is TI.

I am sure there would be complaints galore if it did not work. Well will give it a try then. Thanks again for all your help. Works fine. This is great information. A couple questions: 1. How many of these extenders can be used on a single bus? I thought I saw a limit of 30 somewhere Would you still be able to have the maximum number of devices on a bus as provided by the I2c spec if each connected to the bus via one of these extenders?

It seems that pull up resistor value is critical with this device. But what if you don't know the total number of devices that will be connecting to the network? Can you design for the max number of devices in terms of pull up resistor calculations and still have everythig work when fewer than the maximum number of devices are on the bus? How are these extenders different from the mosfet-based level shifting circuit described at the end of the I2c spec?

Until reading about the dedicated bus extenders, I had planned on using the level shifting circuit on every one of my slave devices to provide the same type of bus extendability provided by these chips. If you use these chips, how many wires do you need for the long-range bus?


thoughts on “I2c distance measurement

Leave a Reply

Your email address will not be published. Required fields are marked *