michael, Author at MitchTech - Page 2 of 14

Home Posts by michael

Peer Guardian on Raspberry Pi

Posted by michael on Jul 8, 2012 in Raspberry Pi, Tutorials | 11 comments

This tutorial will show how to compile and install Peer Guardian on a Raspberry Pi. The process requires the at least the 2012-06-18-wheezy-beta.zip or newer Debian image (or manual kernel re-compilation). This will NOT work with debian6-19-04-2012.zip since the kernel does not have net filtering enabled. Also, you will need a decent sized SD card (4GB at least) … the dependencies alone require 382 MB.

First, install the required package dependencies. In a terminal on the Raspberry Pi:

sudo apt-get install libnetfilter-queue-dev lsb-qt4 libdbus-1-dev qt4-dev-tools libdbus-1-dev libdbus-glib-1-dev firehol firestarter ufw zlib1g-dev

Next, download and extract the Peer Guardian source archive, then change directory to the root of the tree:

wget http://downloads.sourceforge.net/project/peerguardian/PeerGuardian%20Linux/2.1.3/pgl-2.1.3.tar.gz

tar -xvf pgl-2.1.3.tar.gz

cd pgl-2.1.3/

Now we are finally ready to start the build! To compile, run make, then install Peer Guardian with make install:

make

sudo make install

Finally,

sudo /usr/lib/lsb/install_initd /etc/init.d/pgl

Now reboot the Pi:

sudo reboot

And on start-up you will see the confirmation that it starts:

Starting PeerGuardian Linux: pgld.

Note: this takes much longer than usual for the first boot, be patient!

To start the GUI from the LXDE menu, select Internet -> pgl-gui

The default settings are very strict and you will likely want to change them. It even blocks access to the apt sources, so until you changes the settings, even ‘apt-get update’ will fail.

Arduino Physical CPU Gauges

Posted by michael on Jul 3, 2012 in Arduino, Tutorials, Ubuntu | 0 comments

111

Use Arduino and two hobby servos to control physical servo gauges for cpu activity, memory usage, bandwidth, and more. The script uses the python psutil and pyserial modules. The psutil module provides an interface for retrieving information on all running processes and system utilization (CPU, disk, memory, network) providing service similar to command line tools such as ps, top, iostat, and netstat. The servo control portion of the project is based on Arduino-Python 4-Axis Servo Controlby Brian Wendt, and the Arduino sketch is essentially unmodified from the SerialServoControl Sketch on Sparkfun.

Hardware

Connect the red, power lines of the servos to +5v, the black ground lines to GND, and the yellow signal lines to the desired output pins, 5 and 6 in the example (others can be used, but must be PWM capable

You can download my cheesy gauge overlay from here:

http://mitchtech.net/arduino-physical-cpu-gauges/gauges/

Print it out, cut out the gauges, and poke a hole in the lower center of the gauge. Remove the servo horn, slide the shaft through the hole in the gauge printout, and reconnect the servo horn on top of it.

Software

The first step is to install the python psutil and pyserial modules. The easiest way to install it is using the python pip package manager. If you don’t have it installed already, you can install it using apt-get:

sudo apt-get install python-pip

Then install the psutil and pyserial modules:

sudo pip install psutil pyserial

Next, flash the sketch to the Arduino board. You can download it or copy and paste into the Arduino IDE.

/******************************************************* * SerialServoControl Sketch * Written by Ryan Owens for SparkFun Electronics * 7/15/11 * * This sketch listens to serial commands and uses the data * to set the position of two servos. * * Serial Command Structure: 2 bytes - [ID Byte][Servo Position byte] * ID byte should be 0 or 1. * Servo position should be a value between 0 and 180. * Invalid commands are ignored * The servo position is not error checked. * * Hardware Setup * Servos should be connected to pins 5 and 6 of the Arduino. * 9V DC Power supply is recommended as USB can't always handle powering two servos */ #include <Servo.h> //Used to control the Pan/Tilt Servos //These are variables that hold the servo IDs. char tiltChannel=0, panChannel=1; //These are the objects for each servo. Servo servoTilt, servoPan; //This is a character that will hold data from the Serial port. char serialChar=0; void setup(){ servoTilt.attach(5); //The Tilt servo is attached to pin 5. servoPan.attach(6); //The Pan servo is attached to pin 6. servoTilt.write(90); //Initially put the servos both servoPan.write(90); //at 90 degress. Serial.begin(9600); //Set up a serial connection for 9600 bps. } void loop(){ while(Serial.available() <=0); //Wait for a character on the serial port. serialChar = Serial.read(); //Copy the character from the serial port to the variable if(serialChar == tiltChannel){ //Check to see if the character is the servo ID for the tilt servo while(Serial.available() <=0); //Wait for the second command byte from the serial port. servoTilt.write(Serial.read()); //Set the tilt servo position to the value of the second command byte received on the serial port } else if(serialChar == panChannel){ //Check to see if the initial serial character was the servo ID for the pan servo. while(Serial.available() <= 0); //Wait for the second command byte from the serial port. servoPan.write(Serial.read()); //Set the pan servo position to the value of the second command byte received from the serial port. } //If the character is not the pan or tilt servo ID, it is ignored. }

Then download or copy and paste the Python script:

#!/usr/bin/env python import serial, sys, time, psutil # Assign Arduino's serial port address # Windows example # usbport = 'COM3' # Linux example # usbport = '/dev/ttyUSB0' # MacOSX example # usbport = '/dev/tty.usbserial-FTALLOK2' usbport = '/dev/ttyUSB0' # Set up serial baud rate ser = serial.Serial(usbport, 9600, timeout=1) def move(servo, angle): '''Moves the specified servo to the supplied angle. Arguments: servo the servo number to command, an integer from 1-4 angle the desired servo angle, an integer from 0 to 180 (e.g.) >>> servo.move(2, 90) ... # "move servo #2 to 90 degrees"''' if (0 <= angle <= 180): ser.write(chr(255)) ser.write(chr(servo)) ser.write(chr(angle)) else: print "Servo angle must be an integer between 0 and 180.\n" def main(): while 1: cpu_percent = psutil.cpu_percent(interval=1, percpu=False) mem_percent = psutil.phymem_usage().percent cpu_angle = int(cpu_percent / 100 * 180) mem_angle = int(mem_percent / 100 * 180) cpu_str = "CPU: " + str(cpu_percent) + " % (" + str(cpu_angle) + "/180)" mem_str = "Mem: " + str(mem_percent) + " % (" + str(mem_angle) + "/180)" print cpu_str print mem_str move(0, cpu_angle) move(1, mem_angle) #time.sleep(1) if __name__ == "__main__": sys.exit(main())

That’s it! To run the script:

python cpu_serial_servo.py

Note:If you receive this error:

raise SerialException(“could not open port %s: %s” % (self._port, msg)) serial.serialutil.SerialException: could not open port /dev/ttyUSB0: [Errno 13] Permission denied: ‘/dev/ttyUSB0’

The problem is the default permissions of the /dev/ttyUSB0 (or /dev/ttyACM0) device. This can be fixed by running the command:

sudo chmod 777 /dev/ttyUSB0

Raspberry Pi Physical Gmail Notifier

Posted by michael on Jun 29, 2012 in Raspberry Pi, Tutorials | 43 comments

This tutorial will demonstrate how to easily turn your Raspberry Pi into a physical Gmail notifier, in only 10 lines of python! If the configured Gmail account has unread messages, the LED will be illuminated, otherwise dim. The project was inspired by the Arduino/Mac version by J4mie adapted for use on the Raspberry Pi.

Here is a diagram of the wiring of the LED with a 330 ohm resistor in series (created with Fritzing):

The python script uses the feedparser module to simplify interaction with Gmail and the RPi.GPIO module to control the GPIO pins. The easiest way to install these is using the python pip package manager. If you don’t have it installed, you can install the pip package manager using apt-get. In a terminal on the Pi:

EDIT: For 2012-07-15-wheezy-raspbian.zip and newer, the Python development headers (python2.7-dev) are also required:

sudo apt-get install python-pip python2.7-dev

Next, for pip to work correctly you will need to update to a newer version of distribute using easy_install:

sudo easy_install -U distribute

Then install the feedparser and GPIO modules with pip:

sudo pip install feedparser RPi.GPIO

Once the pre-requisites have been installed, download , or copy and paste the following Python script to the Raspberry Pi:

import RPi.GPIO as GPIO, feedparser USERNAME="username@gmail.com" PASSWORD="password" GPIO_PIN=12 GPIO.setmode(GPIO.BOARD) GPIO.setup(GPIO_PIN, GPIO.OUT) newmails = int(feedparser.parse("https://" + USERNAME + ":" + PASSWORD + "@mail.google.com/gmail/feed/atom")["feed"]["fullcount"]) if newmails > 0: GPIO.output(GPIO_PIN, True) else: GPIO.output(GPIO_PIN, False)

The final step is to configure the script to run every minute as a cron job. To do so, open the global crontab for editing:

sudo crontab -e

Then add this line to the end of the file (adjust to the location of the python script):

* * * * * python /home/pi/raspi_gmail.py

That’s it! From now on, cron will execute the script once every minute. If you have unread messages, the GPIO pin will be pulled high, lighting the LED, otherwise, it will be disabled, dimming the LED.

Arduino USB HID Keyboard

Posted by michael on Jun 24, 2012 in Arduino, Tutorials, Ubuntu | 114 comments

138

Turn your Arduino UNO into a USB HID keyboard, and make buttons that do whatever you want. Make it a useful tool, with new buttons for Cut/Copy/Paste or Volume+/Volume-/Mute, or annoy your friends and colleagues by setting the keyboard to perform random keypress after random delays!

The USB HID keyboard conforms to the standard USB specification, so is functional on all modern operating systems. All this is made possible by the use of the Arduino Device Firmware Update (DFU) function.

Arduino Device Firmware Update (DFU)

The Atmega8U2 chip on the Arduino UNO can be programmed directly using the special USB protocol called Device Firmware Update (DFU). This is completely independant of the ‘normal’ method of flashing sketches to the board using the Arduino IDE.

This process is normally used to update the firmware to a more recent version, as explained in the offical Arduino guide, Updating the Atmega8U2 on an Uno or Mega2560 using DFU. Note: If your board is NOT an Arduino UNO SMD you’ll need to solder a 10k resistor (Brown-black-orange) at the back of your board as shown on the Arduino site.

However, in addition to the ability to flash standard USB Serial firmwares, we can also flash alternative firmwares as well. This allows the device to be recognized as many other device types, including keyboard, mouse, joystick, midi device, etc. This is made possible in part to the wonderful open source LUFA (Lightweight USB Framework for AVRs) USB stack, and keyboard HID firmware from Darran.

In this demonstration, we will flash generic USB HID keyboard firmware. The USB HID protocol provides manufactures the generic specifications to interact with nearly every operating system in existence. For more info, check out the USB HID Spec sheet.

Before you start, install the required packages. On Ubuntu and Debain systems, in a terminal run:

sudo apt-get install dfu-programmer dfu-util

For Windows and Mac instructions to install the dfu-programmer tool, consult the official Arduino DFU documentation.

Then download these two firmware files:

Arduino-usbserial.hex
Arduino-keyboard-0.3.hex

The first step is to make sure you are able to flash the standard arduino firmware. This will confirm that the programmer and the environment are both functional. NOTE: There is no chance of ‘bricking’ the device using this method. The Arduino bootloader firmware can always be updated using the DFU protocol!

sudo dfu-programmer at90usb82 erase
sudo dfu-programmer at90usb82 flash --debug 1 Arduino-usbserial.hex
sudo dfu-programmer at90usb82 reset

Plug cycle the Arduino, then open the Arduino IDE and ensure that you can still upload a sketch. Assuming everything flashes normally, we can move forward with flashing the HID keyboard firmware.

sudo dfu-programmer at90usb82 erase
sudo dfu-programmer at90usb82 flash --debug 1 Arduino-keyboard-0.3.hex
sudo dfu-programmer at90usb82 reset

NOTE: The Arduino can only be flashed with skectches through the Adruino IDE if the Arduino-usbserial.hex bootloader is active. So, to develop a USB HID device, the process becomes:

Flash Arduino-usbserial.hex bootloader with dfu-programmer (erase/flash/reset)
Plug cycle the Arduino
Flash firmware sketch using Arduino IDE
Plug cycle the Arduino
Flash Arduino-keyboard-0.3.hex bootloader with dfu-programmer (erase/flash/reset)
Test and repeat

Now that you understand how the process works, you can try out some of these keyboard samples. The easiest example is the random keypress with random delays, since it doesn’t require any components connected to the Arduino.

Random Key/Random Delay

/* Arduino USB HID Keyboard Demo * Random Key/Random Delay */ uint8_t buf[8] = { 0 }; /* Keyboard report buffer */ void setup() { Serial.begin(9600); randomSeed(analogRead(0)); delay(200); } void loop() { int randomChar = random(4, 130); long randomDelay = random(1000, 10000); delay(randomDelay); buf[2] = randomChar; // Random character Serial.write(buf, 8); // Send keypress releaseKey(); } void releaseKey() { buf[0] = 0; buf[2] = 0; Serial.write(buf, 8); // Release key }

The following two examples both use three buttons connected to the Arduino. The code can easily be changed to make the buttons perform other actions, by consulting the mapping tables in the USB HID documentation. Here is a diagram of the circuit, (created with Fritzing):

Volume+/Volume-/Mute

/* Arduino USB Keyboard HID demo * Volume+/Volume-/Mute keys */ uint8_t buf[8] = { 0 }; /* Keyboard report buffer */ #define PIN_VOLUME_UP 5 #define PIN_VOLUME_DOWN 6 #define PIN_MUTE 7 int state = 1; void setup() { Serial.begin(9600); pinMode(PIN_VOLUME_UP, INPUT); pinMode(PIN_VOLUME_DOWN, INPUT); pinMode(PIN_MUTE, INPUT); // enable internal pull-ups digitalWrite(PIN_VOLUME_UP, 1); digitalWrite(PIN_VOLUME_DOWN, 1); digitalWrite(PIN_MUTE, 1); delay(200); } void loop() { state = digitalRead(PIN_VOLUME_UP); if (state != 1) { buf[2] = 128; // Volume up key Serial.write(buf, 8); // Send keypress releaseKey(); } state = digitalRead(PIN_VOLUME_DOWN); if (state != 1) { buf[2] = 129; // Volume down key Serial.write(buf, 8); // Send keypress releaseKey(); } state = digitalRead(PIN_MUTE); if (state != 1) { buf[2] = 127; // Mute key Serial.write(buf, 8); // Send keypress releaseKey(); } } void releaseKey() { buf[0] = 0; buf[2] = 0; Serial.write(buf, 8); // Release key }

Cut/Copy/Paste

/* Arduino USB Keyboard HID demo * Cut/Copy/Paste Keys */ #define KEY_LEFT_CTRL 0x01 #define KEY_LEFT_SHIFT 0x02 #define KEY_RIGHT_CTRL 0x10 #define KEY_RIGHT_SHIFT 0x20 uint8_t buf[8] = { 0 }; /* Keyboard report buffer */ #define PIN_COPY 5 #define PIN_CUT 6 #define PIN_PASTE 7 int state = 1; void setup() { Serial.begin(9600); pinMode(PIN_COPY, INPUT); pinMode(PIN_CUT, INPUT); pinMode(PIN_PASTE, INPUT); // Enable internal pull-ups digitalWrite(PIN_COPY, 1); digitalWrite(PIN_CUT, 1); digitalWrite(PIN_PASTE, 1); delay(200); } void loop() { state = digitalRead(PIN_CUT); if (state != 1) { buf[0] = KEY_LEFT_CTRL; // Ctrl buf[2] = 27; // Letter X // buf[2] = 123; // Cut key: Less portable Serial.write(buf, 8); // Ssend keypress releaseKey(); } state = digitalRead(PIN_COPY); if (state != 1) { buf[0] = KEY_LEFT_CTRL; // Ctrl buf[2] = 6; // Letter C // buf[2] = 124; // Copy key: Less portable Serial.write(buf, 8); // Send keypress releaseKey(); } state = digitalRead(PIN_PASTE); if (state != 1) { buf[0] = KEY_LEFT_CTRL; // Ctrl buf[2] = 25; // Letter V // buf[2] = 125; // Paste key: Less portable Serial.write(buf, 8); // Send keypress releaseKey(); } } void releaseKey() { buf[0] = 0; buf[2] = 0; Serial.write(buf, 8); // Release key delay(500); }

Arduino on Raspberry Pi

Posted by michael on Jun 14, 2012 in Arduino, Raspberry Pi, Tutorials | 13 comments

Connecting an Arduino to a Raspberry Pi is simple. In a terminal, install the Arduino IDE:

sudo apt-get install arduino

This will take a while to download and install all of the dependencies. Once completed, you can start the IDE from the terminal:

arduino

Or, from the LXDE menu, Electronics->Arduino IDE. ~~Note: This is IDE version 0018, and does not seem to recognize boards newer then the Duemilanove.~~ Update: The IDE version in the package manager has been updated to version 1.01 and should work with newer boards like the Uno and Leonardo now as well.

The 1 amp power supply I have connected to my Raspberry Pi was not sufficient to power both the Pi and the Arduino through the USB port, so I connected the Arduino through a powered external USB hub. ~~This may not be necessary with a larger power supply connected to the Pi.~~ Update: A larger power supply will not overcome this limitation; the micro USB port on the Raspberry Pi is fused with 1100mA. –Thanks cavebeat

Alternatively, the 5V GPIO R_Pi Pin can be used to power the Arduino. Just connect the 5V GPIO pin on the Raspberry Pi to the VIN pin on the Arduino, and respectively GND from one board to the other.

This eliminates the need for the externally powered USB hub, but can make development more of a chore due to the USB port restriction: the keyboard and Arduino will need to be swapped in and out to flash the Arduino.

« Older Entries

Next Entries »

Peer Guardian on Raspberry Pi

Arduino Physical CPU Gauges

Hardware

Software

Raspberry Pi Physical Gmail Notifier

Arduino USB HID Keyboard

Arduino Device Firmware Update (DFU)

Random Key/Random Delay

Volume+/Volume-/Mute

Cut/Copy/Paste

Arduino on Raspberry Pi

Recent Posts

#INCLUDE STD_DISCLAIMER

Live Chat

Peer Guardian on Raspberry Pi

Share this:

Arduino Physical CPU Gauges

Hardware

Software

Share this:

Raspberry Pi Physical Gmail Notifier

Share this:

Arduino USB HID Keyboard

Arduino Device Firmware Update (DFU)

Random Key/Random Delay

Volume+/Volume-/Mute

Cut/Copy/Paste

Share this:

Arduino on Raspberry Pi

Share this:

Recent Posts

#INCLUDE STD_DISCLAIMER

Live Chat