Raspberry Pi with a 1.8″ TFT shield

I’m using a shield from Texy to attach my TFT to my Pi.

TFT Shield TFT shield

This is soooo much easier then connecting up the cables individually, which requires me to always refer to the wiring diagram… and it always takes me two or three goes to get it right.

This just requires a quick snap onto the top of the GPIO pins. It also includes wiring to use 3 buttons on the GPIO pins not being used by the TFT.

Look here to find out where you can get one;
http://www.raspberrypi.org/phpBB3/viewtopic.php?f=59&t=40674







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Automatic login between two Raspberry Pi hosts

If you have multiple Raspberry’s or even multiple Unix hosts , you will start to get frustrated at constantly having to enter a password every time you copy files between them or access these devices from another Unix host.


There is an easy way to disable this with RSA key pairs.

  1. On each host, enter ssh-keygen
  2. Hit enter to keep the default directory.
  3. Passphrase.  Leave blank and hit enter
  4. Your keys are created under .ssh/

Now you need to copy over your key to all the other hosts with;
ssh-copy-id -i .ssh/id_rsa.pub username@serverip



Once this is done, you should now be able to copy files or access each device without having to use passwords.

You still need to enter a password when trying to connect from a host that hasn’t got a key.


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Raspberry Pi with a 2.2″ TFT

 

Notro has done some great work with developing drivers for different models of TFT displays for the Pi.
He successfully created one for the Adafruit 2.2″ TFT . This is a great little display and is very clear.

Notro’s Wiki with instructions can be found here.

As with the 1.8″ TFT from Adafruit, this device can be used to display video, images and your own data with easily using pygame.

A couple of images from my Pi running the 2.2 TFT;

photo2.2TFT

PiTFT22-1

 

 
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PiBBot – Robotic Project – Phase 2 – Prototype

Here is my first attempt at getting PiBBot balanced.

This is a very early prototype, confirming that all the hardware works and the I can get the time of the main loop down to 20ms, which was easy.
This prototype also helped me get my head around the code and math need to balance.

 

 

I am waiting on the delivery of some hardware to build my final and larger version.  Which will have a battery pack placed up high, this will help a lot with the balancing.

1stBalance2

 

The main components used to balance this prototype;

  • MinIMU-9 v2 Gyro, Accelerometer, and Compass (L3GD20 and LSM303DLHC Carrier)
  • Solarbotics GM6 120:1 Mini Gear Motor Offset Output
  • Dual H-Bridge Motor Driver
  • 315MHz RF M4 Receiver
  • 12v battery

The receiver allowed my to change the PID values in real time.

There is also a lot of other components on the breadboard, but they are not needed to balance. Eg TFT, 8x8Matrix, Temp monitor…



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Setting up VNC on Raspberry Pi

I run my Pi headless and every now and than I need to access the GUI.
Rather than connecting up a monitor, keyboard and mouse, I use TightVNC.

Below are some quick instructions on how to get this working.



– Install TightVNC

pi@raspberrypi ~ $ sudo apt-get update
pi@raspberrypi ~ $ sudo apt-get install tightvncserver


-To start VNC. When running it for the first time you will be asked for a password.

pi@raspberrypi ~ $ vncserver :1 -geometry 1200x768 -depth 24



-To connect to your Pi from another PC, use TightVNC viewer.
VNC viewer






-To stop TightVNC on your Pi.

pi@raspberrypi ~ $ vncserver -kill :1

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PiBBot – Robotic Project – Phase 1 – Testing Components

This is the first phase on my Balancing Robot project.
Which I think I will call PiBBot. (Pi balancing Bot)

I want to test all the components first before I put them in their final position on the frame for my balancing robot.

Components2
Components1

Hardware list;

  • Raspberry Pi rev 2
  • Two breadboards
  • 1.8″ TFT, connected via SPI
  • Three 8×8 led matrix’s connected via I2C
  • One MinIMU  (Accelerometer, Gyro & Compass) all connected via I2C
  • H-Bridge to control the motors
  • Temperature sensor connected via I2C
  • 315Mhz RF Receiver
  • One LED

Click the image below to see the components named on the breadboard;
Breadboard with Labels

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Raspberry Pi and an 8×8 LED Matrix, using C.

Below is some information on how to get an 8×8 led matrix working on your Raspberry Pi using C.
I have also included the code needed to get text scrolling.

The matrix I am using is this one from Adafruit. This matrix uses a HT16K33 controller chip and communicates with the Pi via the i2c bus.


Adafruit has very good and detailed tutorials on how to solder it up and get i2c working between your Pi and the Matrix.
http://learn.adafruit.com/adafruit-led-backpack/
http://learn.adafruit.com/matrix-7-segment-led-backpack-with-the-raspberry-pi/configuring-your-pi-for-i2c


In brief;

  1. Scan the i2c bus for your device.
  2. Download the code needed.
  3. Compile.
  4. Run.



1. Scan i2c bus

Adafruit have some great instructions in the links above on how to do this.
When using i2cdetect to scan my bus, 0x70 was returned for the address of my matrix.
I am using a Rev B board and my bus is 1. If you get nothing back, check bus 0 with i2cdetect -y 0.

pi@raspberrypi ~ $sudo i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: — — — — — — — — — — — — —
10: — — — — — — — — — — — — — — — —
20: — — — — — — — — — — — — — — — —
30: — — — — — — — — — — — — — — — —
40: — — — — — — — — — — — — — — — —
50: — — — — — — — — — — — — — — — —
60: — — — — — — — — — — — — — — — —
70: 70 — — — — — — —
pi@raspberrypi ~ $




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Blip, blop, bloop…