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Inaccurate readings of Distances (HC-SRO4)

Hi guys! This is my first time in this website. Just newly found out this community of robot enthusiasts, so I guess, and I hope you can help me with this problem, and by the way, I'm also a beginner of this one..


I just brought an ultrasonic sensor. Well it's working well after testing it with a code. But once I put some "if, else" statements, it's giving me inaccurate distances...

for instance... if I give the loop as ReadDist(); (// It is assumed that I've already put the right code for the Ultrasonic Sensor).

void loop()

ESP8266 Troubleshoot

Hello LMRians,

I recently bougt an esp8266 wifi module but when I enter any AT command (or gibrish) I get ERROR in return. What may be the problem?

I have tried all power modules, power is OK. The same thing happens with all modules i have.
Please HELP!!  URGENT!!!!!!!!!!!!!

MPU vs MCU - Which is more suited and what is the best one?

Hello all, brand new to the group.

Ultrasonic Collision Avoidance Arduino and Raspberry Pi


I am building and testing a telepresence wheeled rover bot that has two methods of control:

1. Web Interface (Manual Mode): This consists of a control panel on a web page served using WebIOPi on a Raspberry Pi which, when activated, sends commands to an Arduino Nano AT Mega328P via a two wire i2c interface (Forward, Back etc). 

Ideas Needed for how to open the back door for my dog... remotely?

I have a dog with health problems that needs to go outside a lot.  I'm just tired of getting up for him, and a doggy door is not an option.

I'd like to be able to hit a button from my couch, and have the door open up.  It only needs to open up about 9 inches.  I'm ok with taping down the latch, so I don't need anything that turns the handle.  Just needs to push it open and closed.

Serial vs I2C communication

Hi, please, can you tell me difference between I2C and Serial communication and which is the best for communication Raspberry Pi 2 with Arduino (T'Rex Controller). Thanks

Does this charger work well for Arduino?

Hello everyone! Recently I came across a Justin 5200 mah battery (https://www.youtube.com/watch?v=vNLnQ7RHDuk), and am wondering if anyone else has tried to use this to power an arduino. I've found that some people make use of usb portable chargers, and wonder if anyone has used that brand. It seems to get mixed reviews, but for it's size and even at half power, has more than I need for some of my projects. If you use portable chargers, what charger do you use? Or do you just stick to good ol' batteries?

Thoughts on the Hitec 33485?

I have been looking through higher powered servos for a while, and came across hitec 33485s. The Amazon page comments seem to praise them, but I wanted to hear more thoughts. Can these be relied on, or are there better servos for the price? Has anyone used them?

Controlling 12V stepper motor with L293D

I just got my first stepper motor. I just want to tinker around with it for now. Before I got it I saw many online guides that you can control it with an L293D motor driver. Since I have one of these I bought a stepper motor. My problem is that I forgot to watch for the operating voltage of the motor and I made the mistake of buying a 12V stepper motor. 

PWM switch - autonomous boat with Raspberry Pi

Hello everyone! This is my first post.

Need ideas on a robot arm.

I am looking to make a robot arm that is controlled via radio. 

The arm needs to be able to pick up wooden pieces that can range from 0.5lbs to 10lbs and carry them a fair distance. I already have a moving robot, but I am just stuck on what to do to pick up the pieces. 

I have parts readily available to me as long as if I don't have to buy a whole arm that's already pre made.

I have servos, arduinos, circuits, aluminium sheets - bars - rods - etc.

Servo powering problem

Hi guys, me and my friend have built an arduino controlled Quadruped "mantis" robot.

Seeking worm-drive gearmotor with encoder.

I origially started a thread at RobotShop, but they don't have anything that meets my needs in terms of torque. I am designing a mechanism that needs a Right-Angle gearbox with worm drive. 

I need the following;

Dagu ComMotion Confusion

I purchased a Dagu Scamper to enter the OddBot art contest. Mechanical assemply completed without problems. Trying to get started with the software. Found the ComMotion instruction manual and a package called "ComMotion_Redboard_Demo" which contains four .ino files which compile and load into a Sparkfun redboard.

Tips for having custom parts waterjet cut ⚙

If you have a sophisticated mechanical design for your robot, you may have considered having the parts made by CNC waterjet. But, as with any tool, there are some limitations to this approach. I created thse articles to explain the limitations of this technology and hopefully make it easier to get the custom parts you need from waterjet cutting

Affordable 3D printer? (For small robotics)

Lately I've been getting frustrated with cutting, sanding and drilling wood. It takes lots of time and the quality is low. Im thinking a 3D printer is exactly what I need. Anything from the $300 to $500 range? Cheaper the better? 

Where to start?

So, I'm pretty much a blank slate. I have no knowlege on anything, my question is...where do I start? Is there a how-to guide or something. What is the most basic knowledge I need to know to start? Any direction would be very much appreciated.


Thanks in advance! ^_^

need some info on a humanoid robot for the robo games in the Kung fu event

Hello I'm new to this robot building hobby , my main interest in humanoid bots . I would like to build a bot for the Kung fu event in the robo games in 2017 or maybe 2018 be pending on my robot progress.  I plan to start out with a few kits  like the robots kits with wheels and then when I feel I'm ready get a hexpod bot kit and just working my way up to the humanoid bot .right now I just want to know what I want to know is what do I need to know is what would I need to build the bot for the Kong fu event .


Whats going on with this forum?

Ive been apart of this forum for a while now and ive learned alot from the people here.


Well i had one particular thread asking for help in solving the inverse kinematics which had a lot of good information. Now all that info and comments are all gone. Looks like im asking questions from myself. Every single comment made by anyone but me is gone.


Then i got curious and checked all my threads and they are all that way.


Help needed with Commotion Motor Driver Shield


I am trying to drive 4 motors (pololu.com/product/1445/specs) with the Commotion Motor Driver (https://sites.google.com/site/daguproducts/system/app/pages/search?scope=search-site&q=commotion).

For starters I plugged in one motor, then used the code available here:


And was able to drive the motor two/three times, but could not do that any longer. I am not sure what changed.