Android Phone Drives NXT Robot via ADK Board & NXShield

[pcdevltd]

I've only just seen your video, what a neat use of the ADK board, and really great to see you are using my RealMaze app - I didn't know if anyone else had actually used my instructable until I saw this. Just one thing, there's no link to the ADK, my instructable or my RealMaze video (from the comments it looks like it was there before but was inadvertently removed?) are you able to add a link in your description and/or web page? I'm looking forward to seeing more of your projects! Cheers, Paul

[Cloakmolotov]

This is very advanced for someone as young and inexperienced as you, Nayana!

[pygame100]

So you wrote the code in Python?

[ntchil]

@pygame100 sorry I did not see this comment but no the code for this was not written in python. the code on the android is actually an actual apk android app that was made but using the python scripting layer, you are able to communicate with an android via the usb and achieve a similar task.

[hehegirl]

great job with the car!

i noticed on your documentation that you powered everything with a 9.6 V battery, do you know how long this lasts approximately? i am trying to do a project that connects a usb-host device (either IOIO or arduino mega adk, still undecided) with an android phone, and am also thinking of using the phone's hardware (e.g. GPS, accelerometer, etc). the biggest trouble right now is finding a good solution to power everything. i also want the battery to be re-chargeable as well.

[ntchil]

@hehegirl How long the battery lasts depends completely on what you have connected to the ADK board as well as your Android phone. The ADK board charges the Android phone when it is connected to it so this draws some power. If you have just the ADK board and a fully charges Android phone connected, the ADK board will draw about 50mAh of current and an NXShield will also take about 50 mAh with no motors connected.

[ntchil]

@hehegirl So if you have a 9.6 volt battery with like 1600 mAh, it can run these two for about 16 hours. But the minute your phone starts to discharge, it will start to consume some of the power from the battery. I would concentrate more on the capacity of the battery than the voltage. 9.6 volts or around there is fine for the most part but depending on how much power consuming stuff you have connected, you will need a higher capacity battery

[hehegirl]

@ntchil thank you for replying so quickly! one of the requirements of my project is to have the whole unit log about 16 hours of data continuously, and the data includes information from the GPS, accelerometer, and gyro from the phone plus a linear potentiometer that will feed into a microcontroller (either ADK or IOIO). since you have obviously used the gyroscope, did u come across any documentation that indicates how much current it draws?

[ntchil]

@hehegirl No, I have not come across and specific details like that but the current drawn by the sensors and stuff all has to do with the actual phone you are using. If you disable many of the features on your Android phone, the battery should be able to last much longer. If it is just the sensors you are using it should be fine with minimal phone feature usage. Also, is it possible for you to just use a DC power supply?

[hehegirl]

@ntchil thank you again for replying so fast! we're mounting the data-logger onto a wheelchair to track the location, speed, etc of a person, so unfortunately we cannot use a DC power supply...

[ntchil]

@hehegirl I understand. Will the data-logger on the phone store the data internally or will it upload it to a webserver or something? Because if it stores it internally you can go ahead and disable the network and data features and put it in Super power saver mode and then the battery will last longer. Also, if the wheelchair is electric, it will have a battery perhaps you can draw some power from there? If not, a battery with a large capacity should do the job reasonably well I think.

[hehegirl]

@ntchil You have no idea how grateful I am of your input. The phone will store the data internally and also upload it to a server for backup once a day. I am still in the process of learning how to program in Android, so I don't know if you can put into the code to just shut off the service that backs up the data + Wi-Fi once the upload is complete? And the chair will not be electric.

[ntchil]

@hehegirl No problem! Actually, if you are interested, we are currently working on a protocol to communicate with the Arduino through a TCP port opened by the Arduino by acting as an ADB host. This is similar to what the IOIO uses. ADB is a very powerful utility in Android phones and it allows us to open a bidirectional communication line. For this project, we are actually using the SL4A (it is a Python scripting layer for Android).

[ntchil]

@hehegirl So basically you can write code in python (very very easy compared to JAVA and eclipse and all that stuff) and u use the ADB library to talk with the Arduino. The good part of this is that you don't need a newer Android with 2/3/4, any Android will work and it is so much easier to understand and program. You can basically communicate. We are currently working on developing the protocol, I will have a video with a robot using this protocol in a couple of days.

[hehegirl]

@ntchil Thank you very much for all your help, but we have decided to use the IOIO board so we only need to have one big program running. In terms of battery, we are going to first have everything running then see how much current the whole unit consumes. Thank you again! :D

[hehegirl]

@ntchil and i agree with you, as the phone starts to discharge, it would draw some current from the battery, especially when we are also using so many power-hungry sensors on the phone

so yeah have u come across any documentation about how much current these sensors draw?

[francisroan]

hey how do u make the app for the android

[ntchil]

@francisroan  the app used on the android is the RealMaze app (there is a link for it in the description)

This app is meant for a different application but the arduino code was changed to suite this application. I am currently working on documentation for this project and it should be finished in the next week or so and I will upload it and post the link for it here as well.

[ntchil]

@francisroan hey, i put the link of the documentation for this app on the description to this video. This should guide you through how to make the entire project, if you have any questions feel free to comment

[Haldi4803]

USB hm... wont work with Bluethoot?

[ntchil]

@Haldi4803 Google's ADK APIs are actually made to attach additional hardware through the USB and communicate with it as an accessory. You can certainly communicate with the Arduino through Bluetooth by getting a simple Bluetooth shield for the Arduino and using the Bluetooth in the phone however, the USB ADK rout allows for a much lower latency than communicating via Bluetooth.