MajorAlvega

Hi again. Another project I showed live last weekend at PLUG Braga BRInCKa 2016 - a LEGO Laser Harp: It uses a Mindstorms EV3 to read the light intensity on 8 color sensors. Each color sensor has a 1mW red laser pointing to it so my instrument has 8 "strings" or "chords" (I use two 3-to-1 input multiplexers in order to achieve 8 sensors). All 8 lasers are controled from one EV3 output. I started with 8 LEGO Power Function LEDs and it worked fine... at dark. But at a live show room I knew it would be impossible to use the LEDs (unless for very very short distances) so I opted for lasers. The EV3 runs ev3dev, a linux distro for the EV3. A python script controls the lasers and reads the sensors, sending their state to a linux laptop where another python script plays the notes on a software MIDI synth (EV3 with ev3dev can play MIDI but has not enough power to polyphonic sound so I had to use this client-server configuration). This allows the "instrument" to scale out so I can had more EV3 and more "strings". I don't know now how to play so during the exhibition my wife, when present, played some 8-note children tunes for the public. I have no live video but I have this one at home, still with LEDs and just 7-chords: Sound still needs some improvements (I'm not controlling note length) and hopefully in a later version I will read hands distance to control note amplitude. I will also use some kind of Human Interface Device to change the MIDI soundfont intrument "on the fly" so the artist can change from an harp to a piano or a drum whenever he/she wants (I'm planning to use LEGO Dimensions ToyPad since I can already read NFC tags with it on the EV3). Some technical details (and code) at my blog.

I like when people mention me but honestly I don't expect they do that, sometimes I even feel surprised when they do. And I always try to give credit to people that inspire me. When they are reachable (a blog, a youtube channel...) I try to give them feedback. And if I'm using their code I always inform them, even when it is clearly open sourced - I think everybody deserves to feel proud about their work.

Thanks. I don't mind if this is not considered Technic and moderator changes it to another place. I presented it as Technic and people at the exhibition who asked about it learned something about pneumatics, mechanics, motors, physics... so my goal was reached no matter how it is categorized.

Hello. Last weekend we had our major exhibition at the North of Portugal, PLUG Braga BRInCKa 2016. Me and my wife showed this LEGO aquarium, "As Sereias e a Cidade Perdida" ("The Mermaids and the Lost City"): Water (near 15l) of course, is not LEGO. All other parts are LEGO except some nuts I used: - 2 small M3 nuts inside the shell to force it to go down when air escapes (I'm also not sure if pneumatic tubes are LEGO or not, I got them at bricklink some time ago). Those 2 nuts could probably be replaced with LEGO magnets but I don't care much for purism. - near 140 M5 nuts inside the large green bricks at the bottom to increase weight and prevents all bricks from floating around (could use boat weight bricks, have enough for that but would take lots of space The air compressor is from Sariel - two pumps generate the curtain's bubbles, one pump is for the shell movement and the fourth pump is for the pyramid. There's also a Power Functions Light - one LED inside the pyramid and the other near the shell, behind the dolphin. The idea came after Paredes de Coura Fan Event, in June, where I attended Oton Ribic "Water" presentation. All those blue slopes came from Paredes de Coura and I had to do something with them. For the exhibition I used a few drops of a sodium hypochlorite solution to prevent algae and other micro-organisms to grow. So no real fish could be shown but I used a small Nemo electro-mechanical toy fish that swims a few seconds each time someone knocked the aquarium glass (sorry, forgot to record). A few more photos at flickr

Hehe! Very funny (and clever)

Thanks for the details about the controller. The video that show the difference between native and yours is very interisting, I wonder if it is possible to do the same in python (or include it somehow). I got curious about the pneumatics, I have no experience with pneumatics. Can you detail it further?

Great project! I still remember, some months ago, how it seemed so "organic" when "just" tracking an object... now it seems something from a Terminator movie. And yes, I would appreciate more details.

@JopieK few EV3 sensors are I2C, most are UART (http://www.ev3dev.org/docs/sensors/) But that's great because it allows us to use them in any linux system (not just the Pi, see this post) because the ev3dev project released the drivers as a standalone linux package. So as long as you can connect WeDo/NXT/EV3 devices to your computer, you can use them. WeDo is easy (USB), EV3 UART require a FTDI cable and NXT I2C devices require a I2C adapter. BrickPi is similar to your HAT idea - it's not an HAT, just an add-on board (with an ATMEL inside) that uses the Pi UART and a few other pins. Unfortunately that also means that firmware is needed and the BrickPi firmware doesn't support all NXT/EV3 devices. I've used some touch sensors, the NXT ultrasonic sensor and the NXT motors.

"something" is in the works, but it will take a while... if ever. The ev3dev project is now much more than "only" an operating system. And it is not only for the EV3, as you found out it can also run on Raspberry Pi and BeagleBone - I use the Raspberry Pi with the BrickPi add-on so I can use some NXT/EV3 sensors and motors. One of the thing they're doing is trying to bring something similar to the EV3 environment to run over the operating system. The lms2012-compat, a subproject of the ev3dev, tries to achieve compatibility with the original EV3 software. That would allow us to develop in something like RobotC or LabView. The project is open source and the community is still small. Every help is welcome.

Hi all! About an year ago, while tinkering with lasers and fog, I had this crazy idea of building a laser harp. It finally reached a level where one can actually play it, so I'm showing it here: It's not a great LEGO MOC - just a framework to hold 7 EV3 color sensors and 7 Power Function Lights (to be replaced with 7 red 1 mW lasers in the future). I use 2 Mindsensors multiplexers to connect 6 of the color sensors to 2 of the EV3 inputs. The 7h sensor is connected directly to a third input. The fourth input is reserved for an ultrasonic sensor, I hope to read hands distance to control notes amplitude. The 7 PF Lights are connected to one output port so I can control brightness. A second output port will be used to control a fog machine. I'm running ev3dev (Debian linux for the EV3). It has some support for music but not [yet] for MIDI. I decided to use MIDI because it allows polyphonic sounds and also choosing different instruments so I'm sending the notes to my linux laptop to be played by a software MIDI synthesizer there. Software is very basic, just two python scripts (one at the EV3, the other at my laptop). For those who might be interested, I'm publishing some more details (and the code) at my blog.

They are for Mindstorms NXT or EV3. You can convert LEGO Mindstorms (NXT or EV3) motors to Power Functions with 2 LEGO cables connected in serial: - Converter Cables for NXT (8528) - Power Functions Extension Cable but since I have no Firgelli actuators I cannot assure that it also works with them (most probably it will). If you are in a hurry, you can made your own adapter, connectectin C1 and C2 wires from a Power Functions cable to Motor Power 1 and Motor Power 2 wires from a NXT/EV3 extension cable:. http://www.josepino.com/lego/hacking_lego_nxt

It doesn't work. You have an ordinary Bluetooth dongle, not sure if it supports BT 4.0 BLE commands, but even if it does it will not work - for this to work you do need the BLED112. The BLED112 has a programmable microcontroller on it so it's possible to insert some firmware on it that makes it work as a «broker» between Scratch and the SBrick. It's also the same with LEGO WeDo 2.0.

Not at *that* level but it might interest you since you refer the Pi and the Arduino. I've been testing a light protocol, MQTT, to create a mesh of devices: my laptop, a couple of Mindstorms EV3, a couple of Raspberry Pi's, an Arduino-like (NodeMCU) and my Android phone. I made a very simple tutorial for the ev3dev site: http://www.ev3dev.org/docs/tutorials/sending-and-receiving-messages-with-mqtt/ One advantage I see of using MQTT is using Node-Red on a laptop or a Pi to "coordinate" everything very easily.

So it's not quite just tank length but the tank area? That would explain something that has been puzzling me: Oracid tank uses 4 XL motors and a PF LiPo battery that never clips current. I use smaller tank with just 2 XL motors but when using PF AA battery box with good batteries it clips whenever I force the tank to much. There are other differences in our tanks (mostly suspension) but width seems to be main one.

Olá André! Nice to have another portuguese fellow around here, hope you enjoy.

Hi. I bought a Power Functions 8293 set today, in a Toys R Us here in Portugal. It's the box with the Medium Motor, the Switch, the Battery Pack, the Lights and some gears and axles. The switch doesn't have the reverser switch. But the images printed on the set's box still show a switch with the reverser.

«I was kind of hoping I could get some kind of app to help automate the sbrick but from what everyone says its pretty limited, but I'll see when I get it» SBrick has only outputs for motors (it has also an internal temperature sensure and a voltage meter, useless for this purpose). Most people are using the Vengit native apps (Android, Windows Phone and iOS) but Vengit release information that allows everyone to make their own programm to control it. Unfortunately they didn't release an API so you have to do it all by yourself. I am using python scripts in Linux to control the SBrick. Since EV3 can run linux (ev3dev project) I've used a Raspberry Pi, a laptop and an EV3. I saw recently someone also using my code with a Raspberry Pi, at the Eurobricks trains forum. And there is someone at the Technic/Mindstorms forum doing an Android App that allows using a bluetooth gamepad with the Android to control the SBrick. So there's hope for using the SBrick.

The EV3 motors are more like servo motors - normal motors with tachometer inside. But unlike servo motors, there isn't a closed control circuit, that's up to the EV3. So you can use the motors as normal motors, running continuously, but also as servo motors AND as stepper motors. But as legolifty said, you cannot trust only in the steps/rotations you ordered the motors, there is always something sliping/skewing so sensors are essential in the long run if you don't have/want some kind of periodic recalibration. Of course Mindstorms EV3 isn't the only option. You can do the same with WeDO (first generation works with PF motors) and a computer. But EV3 is more powerful so if you were already considering buying one and money isn't a problem [and for the size of that MOC I would say it isn't] go for it!

Great MOC! You can use the PF motors with the EV3 (I've been using the 8528 cable adapter + PF extension cable solution suggested by KamalMYafi). The EV3 can control 4 independent motors, so if you are using one PF motor to move the cabin and another PF motor to slide the door you need 2x8258 cable adapter and 2x PF extension cables. If you also want to control PF lights you can do the same but for that configuration (3 floors) you will lack 1 EV3 output so it's better to use some kind of mechanical switch at each floor to control the lights instead of using the EV3. For the sensors you may also use touch sensors instead of the color sensors (costs ~ half), just need a more complex program to understand in what floor the elevator cabin is (and maybe forcing the cabin to go to the first floor at start-up).

Unless you modified your LEGO battery, you can't get much more than 800 mA from it so the internal overcurrent protection is triping. The SBrick can handle short peaks of 3.5A per channel and VERY SHORT peaks of 6A total but you need a custom battery like those used in RC hobby models. Sorry, there's another possibility... is the battery really shutting off or is just the SBrick shutting off or even just loosing connection? My Android (Sony Xperia Z1) had some bluetooth connection problems with the SBrick. Things got much better with firmware upgrade (4.2b to 4.8) and even better with last App upgrade.

I didn't point the SBrick because he wants 16 motors. Even the SBrick cannot deal with that. The App can associate 2 SBricks, but isn't enough (6A total) for 16 motors. And you can only get 3A if you use a special battery, PF batteries cut at 0.8A.

If you need batteries and purism: use the Power Functions IR as a relay: control a M or L motor to rotate 8 PF switches at the same time, then connect a PF battery and 2 XL motors to each switch. Yes, 8 batteries. If you don't need purism and know some electronics you may try an Arduino with several motor shields and a Infrared shield and a good RC LiPo /LiFe battery that can handle 8A continuous discharge. But I got curious... why so many XL motors? And do you really need full power for all at the same time? If not, you may use less batteries. Uh, sorry, read XL motors. But it's the same solution, just perhaps less PF switches and batteries, maybe 3 L-motors per switch/battery.

Great work!!! (As I don't understand German) how do you control the motors? Several RCX/NXT? By hand?

Eneloop got famous some years ago for their low internal resistant (and not for their capacity). They are NiMH but have a very low discharge rate so are quite good to charge at home and take to an exhibition. The low internal resistance allows very high discharge rates so they perform more like LiPo batteries but can be charged with ordinary AA or AAA chargers. There are other low resistence / high performance brands in the market today, some probably even better. But the name Eneloop is strong in the market and in people memory.

There is some confusion with the PWM pins: you can have PWM function in almost all pins but it seems to be "software PWM" - documentation isn't very clear. NodeMCU functions documentation says "Only 6 pins can be set to PWM mode at the most." But even only 2 PWM can be enough, you can use 2 PWM for 2 motors - 1 for each "enable" pin, and use 2 normal GPIO to control the direction. And if you use modified RC servos (continuous rotation instead of just 0-180 degrees range, sometimes used in robotics) you can use just the PWM pins, no need for direction pins (but code gets more complex).