Friday, April 19, 2013

My Raspberry-Pi Experience

(I haven't written in this blog for long time.
Well, using raspberry pi is kinda linux stuff.  However, my goal is to make it a robot, so let's put what I've experienced here.  These are my baby steps' log. )


Date: 121220 (logged in 2013)

I tried a model B 256MB during 2012 Christmas.  Running Raspbian (build 2012-10-28) on it was surprisingly smooth.  The bottleneck was all about the slow SD card.  Once the programs were loaded up, they ran with good responsiveness.  Raspbian is a modified version of Debian, to support a ARM chip with VFP.  See hardware, and wiki.

Compiling programs on it using GCC is possible but very slow due to its lack of processing power CPU.  Instead, you can cross-compile the applications in linux.


Date: 130415



I ordered a model A-256MB and a model B-512MB.  It took only 2 days to arrive that I was totally impressed.


Model A has half memory, only one usb port and no ethernet port build-in.  I ordered it for its less power consumption, hopefully to extend the battery life if any.  (still not sure if a wise idea)


Date: 130419

First playing with the A board...

Model A couldn't recognize my basic USB hub, the same one that was running okay on the 'B' .  I assume it needs powered hub.  Will get one later.

I also get a WIFI adaptor, TL-WN725N.  A page on eLinux.org said hardware version 1.0 works out of the box.  ie. ver 2.0 needs some .ko file.  Google it if you need it.  Pre-setup the wlan0 on the SD card before plugging into the A board.  Once it power up, it automatically connected to my wireless router.  Nice.  Even better if i can find the command line wlan0 setup... (to be cont..)

I also try hooking up a no-brand linux compatible USB Ethernet Adaptor to A-board's only USB port.  Works right away. 


Date: 130509

ref: http://elinux.org/RPi_VerifiedPeripherals
Extend model A with a powered usb hub: startech.com  ST7202USB, tested in 15 mins:
- power pi A from the hub: YES
- keyboard/mouse: YES
- wifi adaptor: YES
- usb-to-lan adaptor: seems OKAY.  i could see eth0 detected.  not yet actually connected a lan cable though.  will try...
- disconnection: possibly - wlan0 was reset once while i tried to set up using WPS.  will continue monitoring.

in general, i am happy!   :)

Date: 130526

Playing with the GPIO.
Some page warns that GPIO uses 3.3V logic, not 5V commonly in TTL.
It is highly recommended that using protective circuits on all I/Os, eg. zener diodes.
I had been making the breakout board.  Then found out there's breakout board kit available saving you time shopping for different components. 
(tbc...)


Date: 160826

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posted by Ken Seto @ 7:37 PM   0 comments