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.
- On each host, enter ssh-keygen
- Hit enter to keep the default directory.
- Passphrase. Leave blank and hit enter
- 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.
Continue reading Automatic login between two Raspberry Pi hosts
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;
Continue reading Raspberry Pi with a 2.2″ TFT
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.
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…
Continue reading PiBBot – Robotic Project – Phase 2 – Prototype
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.
-To stop TightVNC on your Pi.
pi@raspberrypi ~ $ vncserver -kill :1
Continue reading Setting up VNC on Raspberry Pi
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.
- 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;
Continue reading PiBBot – Robotic Project – Phase 1 – Testing Components
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.
- Scan the i2c bus for your device.
- Download the code needed.
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 ~ $
Continue reading Raspberry Pi and an 8×8 LED Matrix, using C.
Below is some detail regarding the latest project I have been working on. Which is near completion.
I plan to wire it up permanently, place within a case and wall mount it.
Some of the images don’t come up too great in the video, I have included the actual images used here;
I created a simple one line bash script that polls for the temperature every 5 mins.
The main python program uses pygame to write to the TFT via a framebuffer and Matplotlib is used to create the Graphs.
The display can be changed by either the button on the breadboard or via the remote FOB.
Continue reading Raspberry Pi, 1.8″ TFT, RF Receiver and Temperature Sensor