Let's Make Robots!

How to hook up two serial outputs to one serial input

Hey all,

 So I'm working on a project where I'm using two processors and one of the things that I want to do is use one bluetooth device and have two microprocs communicate with it or send data through it. Of course this is not at the same time.

One chip would be the main com device, the other would send stored data when instructed to. I don't want to use one device as a passthrough as this would seem a little inefficient. so I came up with a schematic of what I think might work.

How do I control 18 digital servos with a 28x1?

How do I control 18 digital servos with a Picaxe 28x1?

I have the microcontroller board with the 28x1 mounted and I've tried building the "start here" robo. 

 I now would like to know how to be able to control 18 digital servos since I am building a Hexapod :)

All I really need to know is what extensionboard I need.

Thanks in advance :) Please let me know if you need more info.

Peculiar ldr problem...

Hi, well got my robot to follow light, to see if everything was working fine, but the weird thing is, instead of changing direction in real time, it only changes direction when i reset my arduino board, same thing happens if i watch the serial monitor.

 

for example

 

it prints out 500 to the serial monitor

keeps printing 500, even if i change the light source.

SF order on it's way[shipped!]

Since it's been a while since anyone has posted on this forum, just thought I'd post something.

Finally put my order in thats been in the cart on that fateful freeday. added a couple extra things to it as well since I have a mini project going.

Opted to get the polulu trex motor driver as well since my hbridge attempt has yet to work(though I haven't tried to trouble shoot it for a while) .

Got a couple of 20x2's to see what they are like and since they had some sweet hw access. Grabbed a couple of atmel 2313's since they have built in uarts.  

Damn those LCDs

Rightyo, sparkfun 16x2 serial lcd hooked up to 3.3v, gnd, and the tx pin on my arduino. I just want an example of really basic code that will print something on the lcd, i've searched the arduino site and google but none of the tutorials seem to make sense. is the move to x character command necessary? I just want print like the values from a sensor or what not which seems easy if i could just have it print something simple.

 

 this is my code:

Banebots motor mounting

So i have a pair of banebots motors (http://banebots.com/pc/MP-36XXX-540/MP-36064-540)

I was working on the chassis for my latest robot, but, I could not find a suitable way to mount these motors on my plywood chassis. They have mounting holes, but they aren't very deep. Any suggestions?

ADXL335 vs MMA7260QT

Is the ADXL335 accelerometer better (faster, more precise, less noisy...) than the MMA7260QT sensor?

The ADXL335 based solution at my local robot shop is slightly more expensive, and judging from the product description it's "the holy grail". The MMA7260QT BoB on the other hand has a build in voltage regulator so it's usable with 5V which could come in handy. Though I'm primarily going to use it with an Arduino which seems to be able to provide 3.3V so that might not be a problem either way.

Project: graphing with graphical LCD using microcontroller

anyone knows what LCd best suits my project?.. the project goes like this: An LCD will dipslay a graph of temperature profile of a heater -- that is, a thermocouple connected to the heater sends signals to the microcontroller and the microcontroller must send signals to the LCD to graph the temperature versus time line graph.

If anyone knows, how should the program go?..please help me

Help...Need to build wireless robot

hi all. I'm a beginner.

i need to build a robot driving to wheels.

controlled wirelessly through a laptop 

and need to have atleast 4 channels 

transmit video from 2 cameras to the laptop(range 100m) 

 

presently i'm using arduino to control the robot.

please suggest me what i can use to make those above possible.

i lesser range will do. 

 

 

Controlling 2 lcds

How would i control 2 16x2 lcds using a arduino mega? I know how to control 1 but i do not understand how to control 2 of them. Edit: i want to control them separately and i would hope i could just use the normal, non serial ones. That is i want to be able to use the liquid crystal library but that from what i can tell only controls one because when you lcd.print you are not saying to which one to print. I understand arduino mega has multiple serial lines so i guess maybe that would make it possible to use multiple serial lcds but i am not sure.

Navigation with (2) sonars Update 2 (with data)

*****Update 2.16.10*****

Got some data to start thinking about, guys. My thoughts of getting nice, even packs of 4 or 5 is a little out the window. To be honest, I tried to forget that I could see where the robot was facing and tried to make a decision where to go based on just the readings. I couldn't . Please note that I was seeing the readings on a LCD so left was above right not in a straight line. --Now that I think of it, I have no idea why I didn't line them up as it is a 16x2 display. Huh.

All readings were taken L to R

L293D motor driver and Tamiya 70097

hi all i bought a Tamiya 70097 Twin-Motor Gearbox but the motors don't spin when used with a L293D driver IC but it works ok when it connects directly to the barrery (5v). i have a different 6v motor which works fine with the driver IC so i know it should work.

crash question

how do you awoid that your robot drive over the cleff, or down the stairs?

Cant find any solution, as it have to know that the edge is there in time to either stop, or drive around it. And right now i cant see any way that ultrasonic, IR or any other sensor that can detect that kind of ting from a distance.

Any1 know how to solve this?

servo misbehaving without a control signal... :(

hi all, I'm trying to control some servos (Turnigy TG9e) using an Arduino. I use external power for the servos (5V, 3Amp), and keep the grounds together.

 the problem is that during RESET (or startup), the servos jumps fast to an out-of-range dangerous zone...

I tried adding resistors any many places (from the control pin to the ground, in between the control pin and the servo, and even between the control pin and the positive terminal) - didn't help.

Scary robots

If you hade the time and money, how would you construct the scariest robot possible?

 

I think I'd go for a sugary cute doll robot, stuffed with hidden evil electronics :) Using a tiny camera and face regognition, the robot would wait idly until there's only one person nearby and then slowly turn it's head and eyes to look at him/her. Unless it turned out too cheesy the robot would also say stuff like "seven days" (and because of the face regognition it could maintain individual counters for it's victims) or just laugh diabolically.

Servo torque question

I'm planning to build a robotic arm and need to know what servos to use.
Can someone tell me if my math is correct here?

When i take a servo that has a torque of 240 oz-in (17 kg-cm) and use that as shoulder joint.
A 20 cm long arm would be able to lift a maximum of 17 / 20 = 0.85 kg ?

 

Ultrasonic sensors and pets

Hey all. I'm thinking about building my first robot. Was hoping to build some kind of wheeled monstrosity with lots of sensors, but I beginning to think using ultrasonic sensors might not be a good idea with a cat in the apartment. Does anyone know how pets react to the ultrasonic signals?

picaxe and l293d

if i got this right using a picaxe 28x1 project board (http://www.rev-ed.co.uk/docs/AXE020.pdf) and a l293d motor controller i can control  only 2 motors. For my robot i will need to control 6 motors. What can i do? is there a way to connect more than one l293d to my project board? (all motors must be able to move both directions) 

Problem on Picaxe 28X1

Hello I am trying to do http://letsmakerobots.com/start project. I got Pixace 28x1 . I am amature with soldering. However I tryed soldering motors into my project board. The thing is that the one motor doesnt work.