Aventuras y Desventuras de un hobbyist

Aventuras y Desventuras de un hobbyist....

Line Following Robot

Goal: Build hardware and software for a line follower robot(I think the category is called sniffer)

This robot has to go as fast as possible,  must be able to take sharp turns as low as 90 degrees and it has also to be able to read marks on the side of the main line.

I have started this project a couple of months ago and I have not done as much as I wanted due to work related task taking the most of my time.

For the hardware I am going to use:

UPDATE: first prototype

In the software side I am going to do the programming using C on Atmel Studio v6.

The sensors are going to get analog values from which a "position" will be determinated. The aimed position is going to be the middle point.

In order to drive the motors in a efficient way I am going to use PD control (Proportional and Derivative).

Right now I am working in a telemetry system that allows me to find the best PD performance.

For this I am going to use a small Bluetooth module from DX JY-MCU Arduino Bluetooth Wireless Serial Port Module
and on the PC I hope to make an interface using python that will connect to the COM port and get the values send by the board and display them in a nice graph using smoothiecharts

UPDATE: Telemetry done:

Once the above goals are complete I'll jump to another more specific topics for the line follower such reading marks, taking sharp turns, etc.

So far I am still researching on the best way of programming the robot so I may get one of this this three styles:
  1. Reactive Style or reading sensors and actuating
  2. Behaviour control based on fancy state machines.
  3. Real time programming using a small OS or a basic scheduler.

Arduino Leonardo + Ethernet Shield

Escribo este post a raíz de una pregunta formulada en el foro de Arduino en español.

El problema: 

Los Ethernet Shields no fucionan con la Placa Vinciduino.

El razonamiento:

Los Ethernet shields usan los pines 10,11,12,13 en el Arduino Uno/duemilanove y el pinout es el siguiente:

Pin Arudino Uno pin microcontroller
10 SS
13 SCK

En el diseño de Viciduino o Leonardo boards para aprovechar la mayor cantidad de pines del micro(Atmega32u4) se han movido los pines del SPI al conector ISCP

Y el pin SS ha sido asignado al Rx-LED

Pruebas realizadas:

He conectado los pines del ISCP de Vinciduino con los pines de arduino de la siguiente manera:
Eth Shield Vinciduino ISCP
13 SCK
Ahora bien para poder coger la senal del SS(PB0) del micro he desoldado la resistencia del RXLED para poder soldar un cable y conectarlo al pin 10 del Ethernet shield:

Fucsia = resistencia a quitar
Rojo = pad donde soldé el cable que iría al pin 10 del ethernet shield.

Una vez realizadas las conexiones  me encuentro con que tampoco funciona, y me doy cuenta que el ansia ha podido conmigo ya que no he revisado el código de la librería Ethernet.
##(hacia mucho que no cogía el soldador)

Luego de revisar la librería Ethernet me encuentro con que el equipo Arduino ha editado el archivo w5100.h y han  creado un SS virtual en el pin 10(PB6) de Leonardo/Vinciduino.
Finalmente conecte el pin 10 de Vinciduino al pin1 10 del Ethernet shield y ha funcionado correctamente.

Solución Final:

Simplemente conectar los pines del SCK, MISO,MOSI del  ISCP en nuestra Vinciduino a los pines del ethernet Shield y también el pin  10 de Vinciduino al pin 10 de la Ethernet Shield.
Tal que así:

Vinciduino(Atmega32u4) + LUFA

  1. USB Virtual Serial
    1. Cambiar estas lineas en el makefile:
      1. MCU = atmega32u4
      2. F_CPU = 16000000
    2. Por defecto viene el ejemplo echo.Usando hTerm envio datos y MCU devuelve lo mismo.
  2. USB Virtual Serial ADC
    1. Cambiar estas lineas en el makefile:
      1. MCU = atmega32u4
      2. F_CPU = 16000000
    2. Por defecto viene la lectura analog0 y analog1(PF5 y PF4 en el 32u4)
    3. Edito/anhado la asignación de channels en "USBVirtualSerial-ADC.c".
    4. /*Cambio esto para que coincida con Vinci.
      if ((count = fread(&buffer, 1, CDC_TXRX_EPSIZE, &USBSerialStream)) > 0) {
         // if host sent a 0, send back value of ADC channel 0, if a 1 then channel 1
         // there is only one ADC with multiplexed inputs so only one channel can be converted at a time
         tempByte = buffer[0];
         if (tempByte == '5') {
          ADC_StartReading(ADC_CHANNEL0 | ADC_REFERENCE_AVCC); // start reading channel 0 in the background
          waitingForADCResult = 1;
    5. Finalmente para que coincida con la serigrafia de Vinciduino: 
      1. En hTerm envio 0 -->leo y recibo PF7 en el 32u4--->analog0 serigrafia Vinci.
      2. En hTerm envio 1 -->leo y recibo PF6 en el 32u4--->analog1 serigrafia Vinci.
      3. En hTerm envio 2 -->leo y recibo PF5 en el 32u4--->analog2 serigrafia Vinci.
      4. En hTerm envio 3 -->leo y recibo PF4 en el 32u4--->analog3 serigrafia Vinci.
      5. En hTerm envio 4 -->leo y recibo PF1 en el 32u4--->analog4 serigrafia Vinci.
      6. En hTerm envio 5 -->leo y recibo PF0 en el 32u4--->analog5 serigrafia Vinci.
  3. USB Virtual Serial I2C {pending}
  4. USB Virtual Serial LCD {pending}
  5. USB Virtual Serial SPI {pending}
  6. USBtoSerial {pending}
  7. USB Virtual_FreeRTOS {pending}

nRF24L01 + Arduino

I will keep working on the concept of IOT(internet of things).

Wireless connections are the standard of todays comunications therfore the IOT should follow this path.

Xbee are very reliable way of comunicating wirelessly however this devices are very expensive, I set myself to find a cheap and reliable way of comunicating devices using RF, so after sometime I expend reading on Internet I finally found the nRF24L01 module from Iteadstudio for $ 5.50 nRF24L01 module

They provide a couple of code examples but they pretty poor.
Luckily I found one library in the Arduino website called MIRF and another most powerfull library created named nRFL2401 http://maniacbug.wordpress.com the later the one I am going to use in this write up.

-----Descarga la libreria nRFL2401 ----

First of all we are going to setup the hardware connections;


nRFL01 Arduino nRFL01 Arduino
MOSI 11 SCK 13
CSN 10 CE 9
Vcc 3.3V Gnd Gnd

As per the datasheet specs it is very important to provided 3.3 Volts to the module(Do not provide 5V as it will damage your module)

Once we have the connections set we are going to start by loading the "Getting started" example  from the nRFL01 library.

Once you have loaded the example open up the Serial Monitor on the Arduino IDE a 57600 , if all went OK you should see something like this:

ROLE: Pong back
RX_ADDR_P0-1 = 0xf0f0f0f0d2 0xf0f0f0f0e1
RX_ADDR_P2-5 = 0xc3 0xc4 0xc5 0xc6
TX_ADDR = 0xf0f0f0f0d2
RX_PW_P0-6 = 0x08 0x08 0x00 0x00 0x00 0x00
EN_AA = 0x3f
EN_RXADDR = 0x03
RF_CH = 0x4c
RF_SETUP = 0x07
CONFIG = 0x0f
DYNPD/FEATURE = 0x00 0x00
Data Rate = 1MBPS
Model = nRF24L01
CRC Length = 16 bits
PA Power = PA_HIGH

Si los resultados de las variables son un montón de Ceros "0" revisa tus conexiones porque algo no debe estar conectado correctamente.
Este primer modulo sera el receptor.
Si todo va bien carga el mismo sketch"Getting started" a otro arduino.
y sigue el mismo procedimiento este segundo  modulo sera el transmisor, para ponerlo en modo transmision abre el Serial  Monitor de Arduino y escribe una 'T' y veras que los transmisores empiezan a comunicarse:

Now sending 9369...ok...Got response 9369, round-trip delay: 27
Now sending 10399...ok...Got response 10399, round-trip delay: 29
Now sending 11431...ok...Got response 11431, round-trip delay: 27
Now sending 12462...ok...Got response 12462, round-trip delay: 28

Arduino + WebSockets II

Please read the first part of this serie: http://yopero-tech.blogspot.com/2012/02/arduino-websockets.html

This project describes how to use WebSockets to display data  taken from Arduino and broadcast it to any Browser with WebSocket support. Test your browser here: http://websocket.org/echo.html

First of all we need to decide what data to display and  what to control in Arduino from the  web page .

In this example I am going to control 3 remote controlled relays that you can buy at your hardware store and I want to display the values from 2 temperature sensors.(DS18S20)

This project is composed out of 3 main parts of software apart from the hardware(Arduino Board):

  1. WebSocket  Server:
    1. Python
    2. Autobahn
      1. Twisted
        1. PySerial
  2. MCU (Micro Controller Unit)
    1. Arduino Board(Vinciduino in my case).
    2. Arduino IDE or AVR studio.
  3. Client:
    1. Any web server, I use xampp or python to test as localhost.

The WebSocket server I setup is run under Windows XP:

First thing is to install Python in my case I have used v 2.7

On Python I have installed the following packages:

If you have installed all of the above, download the files of the project from here:
Now that we have the WS server I will jump to the Arduino side of the project, as said above I will control 3 lights interactivity and I will get real time data from 2 temperature sensors.
To accomplish that I have hacked the remote control and connected it to the Arduino
You can see my setup in the video at the end of the post.

The Arduino sketch for my setup at the end of this entry( too long to put  in the middle of the entry)

This sketch sends the values of the 2 temperature sensors with id = 1 or 2 in format JSON
Id  \t value
I would say that this is the most important part of the project, send JSON formated data from arduino to python and then python to digest it and broadcast via WS. 
   celsius = (float)raw / 16.0;
   //Sending JSON 
    printFloat(celsius , 0);    
    //finish sending JSON
later this data is read by the WebSocket server and dispatch to the browser.
def lineReceived(self, line):
         ## parse data received from MCU
         data = [int(x) for x in line.split()]

         ## construct PubSub event from raw data
         evt = {'id': data[0], 'value': data[1]}

         ## publish event to all clients subscribed to topic
         self.wsMcuFactory._dispatchEvent("http://example.com/mcu#analog-value", evt)

         log.msg("Analog value: %s" % str(evt));
      except ValueError:
         log.err('Unable to parse value %s' % line)

In order to display the values given by Arduino and received by the Websocket server I am  using Smoothie Charts; is a really small charting library designed for live streaming data.( http://smoothiecharts.org/)

The final results as you see in the video and screenshots.

In the future I will try to load the WebSocket(C++)client directly to a Arduino with an ethernet shield to avoid the use of a PC, but I am not sure how it will impact the infrastructure side of my LAN(opening ports).

Click "Mas informacíon" to preview the Arduino code

Arduino + WebSockets I


Lately I have been exploring ways of plotting data from a MCU to a web browser, at first I was using arduino and firmata which basically allows you to get nice graphics but implementing it to be connected to a webserver was kind of difficult.
Then we have the option of using Ethernet shields but it lacks of enough memory to write good looking web pages, this can be fixed by using short php commands and the process the rest on a webserver however this solutions only applies to projects that do not need speed and real time connections between server and client/web browser.
An example of that is controlling lights, in this case we only need that the light switches on we do not really care about speed, but imagine if you want to control via web an AUV(Autonomous Underwater vehicle) the scenario changes dramatically because what is needed is accuracy and real time communication between web browser and server which is connected to our MCU via RS232,XBEE,Wireless,Ethernet, etc.(I know this scenario is not very common but hey… this paper and websockets technology is experimental so the scenarios too).
I have also explored Python and Pyserial and  I must say that python is so powerful as you can get lots of things with few lines (although you need first to learn it J)
After exploring Python and some packages such as wxPython, PyQt4, PyGtk you can build nice apps to be run on your computer but it was not good enough for me I really like the look of a webpage so I kept searching until I read something about a real fast technology tested on financial applications, that’s the way I heard about WebSockets and then I thought I may use it with my Arduino.
After looking on internet I found that some people has already used web sockets to communicate with a MCU; people from http://mbed.org/cookbook/IOT uses Tornado a python server but unfortunately it does not run on windows due to a Unix dependency.
As I had my computer already setup with python I went looking for a stand alone websocket package, it took me awhile to find a nice piece of code in http://www.tavendo.de/autobahn/ Autobahn provides client and server implementations of WebSockets for Python and Android.
They have the repocitory in github: https://github.com/oberstet/Autobahn and a google group @ http://groups.google.com/group/autobahnws
After contacting with Tobias O. the owner of this repository I presented him what I want to achieve and he helped me a lot.

Now some theory about WebSockets:

What are WebSockets?

“”WebSockets is a technique for two-way communication over one (TCP) socket, a type of PUSH technology. At the moment, it’s still being standardized by the W3C; however, the latest versions of Chrome and Safari have support for WebSockets.””

What do WebSockets Replace?

Although the real purpose of WebSockets. was not primarily designed to replace any of the things that are already in place and working well. For example, it was not designed to be a low-overhead version of AJAX. The purpose is to provide a bidirectional, low latency, full duplex, communication channel between the browser and server. It's real purpose is to enable a new domain of web applications or to improve current ones that are abusing HTTP to achieve bidirectional communication.
But…..Websockets can replace long-polling. This is an interesting concept; the client sends a request to the server – now, rather than the server responding with data it may not have, it essentially keeps the connection open until the fresh, up-to-date data is ready to be sent – the client next receives this, and sends another request. This has its benefits: decreased latency being one of them, as a connection which has already been opened does not require a new connection to be established. However, long-polling isn’t really a piece of fancy technology: it’s also possible for a request to time-out, and thus a new connection will be needed anyway.
Many Ajax applications make use of the above – this can often be attributed to poor resource utilization.
Wouldn’t it be great if the server could wake up one morning and send its data to clients who are willing to listen without some sort of pre established connection? Welcome to the world of PUSH technology!

Next post I will describe the technical part of this project.

Tennis/Padel Scoreboard II

Aprovechando esta primera semana del año he terminado este proyecto que tenia pendiente.

 He aquí un vídeo de su funcionamiento:

 ..y este link a la primera parte del post Tennis/Padel Scoreboard