The plan:
1. Get the BeagleBone powered and figure out how to get the touchscreen working
2. Figure out if the OS for the BeagleBone has python.
3. Study the python code from the demo and glue in tcl/tk file selection dialogs where appropriate to make it more user friendly.
4. Migrate everything over to the Raspberry Pi. Supposedly all the python will be nicely portable.
Notes for each step:
1. Get the BeagleBone powered and figure out how to get the touchscreen working:
Fortunately for me, this was all already working. The hardest part was making sure that I had the polarity of my power chord correct (center positive) and that I was using a supply capable of powering the screen (needed to be 2A). In the end, I am temporarily fudging it with my cut USB chord with power plug wired on that I made for testing the GSE circuit board. The first USB power block that I tried was only 1.2A and this was insufficient, but most dual power blocks supply 2A and one of those runs it just fine. The Beagle Board website actually has very helpful links to recommended power supplies from DigiKey (http://beagleboard.org/peripheral). The Beagle Board powered up fine over USB and I'm able to use my trusty PuTTY to log into it using the default password over the USB cable. With the 2A power to the LCD7, the board finds the screen automatically, and loads a desktop GUI without any fiddling required. It turns out that the microSD card that came with the BeagleBone has a Linux distribution called "Angstrom" that is fully integrated with a Gnome desktop. The only disappointment is that the touchscreen is barely able to control this GUI without a keyboard and mouse. It is possible to drag the mouse pointer around with a finger to the screen, click by pressing, but the resolution of the GUI is so high that it's difficult to position the mouse pointer precisely enough by touch, and there doesn't seem to be an on-screen keyboard (I got an on-screen keyboard in a later Angstrom distribution that I tried, but it's not like an iPhone where it pops up when needed and is optimized for mobile use).
2. Figure out if the OS for the BeagleBone has python.
Once I got a USB keyboard and mouse connected, starting a terminal window and typing "which python" answered the question of whether python was installed. Directly starting python by just typing "python" got me the python prompt. But then, shockingly, "import Tkinter" failed. I could import other standard libraries and execute other python commands, but no Tkinter, tkinter, or _tkinter. Googling has revealed that everybody else has this problem as well. A variety of solutions have been tried, apparently. These include: a) Doing package updates in Angstrom to get Tkinter, but it seems that a simple package update is not sufficient and "rebuilding python" is required! That sounded like way too much, but somebody on a forum thread suggested b) trying out Ubuntu instead. Sadly, I've learned that the BeagleBone distribution of Ubuntu does not come with a desktop interface installed by default like in Angstrom, and its python distribution doesn't come with Tkinter either. However, in the process I learned how to get disk images for both Angstrom and Ubuntu and load them to a microSD card from the safety of my Windows laptop. Notes follow:
b. Get Ubuntu:
I started by first trying to download a new distribution of Angstrom and booting the BB from it, and it worked great. The following link contained perfect handholding for how to get the image file, where to get 7Zip for unpacking it, and where to get a Windows app for writing it to an SD card:
http://beagleboard.org/getting-started#update
Interestingly, the SD card writer app is apparently distributed by Ubuntu. Here is Ubuntu's own page about the App (and other methods of writing SD card images that don't apply to my attempts to do it from Windows):
https://help.ubuntu.com/community/Installation/FromImgFiles
The new Angstrom distribution booted up to the desktop like the original Angstrom distribution that came with the Beagle Board, but still didn't have Tkinter installed.
I was able to repeat the same image installation steps from the above guide while using the Ubuntu image pointed to from here:
http://elinux.org/BeagleBoardUbuntu#BeagleBone_White.2FBlack.2FGreen
Trying it out, I got the familiar screenfuls of grubloader lines on the LCD7, which means that it found the screen. However, no GUI! I logged in using the default password for the distribution, did a "which python" and "python" and to my surprise, still no Tkinter! While I had learned how to get Ubuntu, it hadn't solved my problem, and it turns out that I have to install a gui manually. As far as I can tell, this also means doing the step which I've so far tried to avoid which is putting the BeagleBone on a network. This is something that can't do at work, ironically enough, because of our locked-down IP assignments, and I don't have a Wi-Fi cape for the Beagle Bone, which means the only place I have to plug it into is my router at home.
Here's probably the best link which explains which packages to download and install to get Tkinter in Ubuntu and mentions the command to do the rebuild (the first comment mentions it, but scroll down to the nicer example in the second comment). This thread in particular applies to my case because I noticed that my distribution of Ubuntu had python 2.7 like the OP of this thread:
http://stackoverflow.com/questions/11752174/how-to-get-tkinter-working-with-ubuntus-default-python-2-7-install
This is the link that describes needing to install tk-dev!
The above link points to this sort of unrelated thread which has a very nice reply from someone about the general process for building Python in Ubuntu:
http://stackoverflow.com/questions/6171210/building-python-and-more-on-missing-modules
So, I read a bunch of threads about how to get a GUI for Ubuntu. Most of them agree that for BeagleBone the best one to try is LXDE. Sadly, a lot of people out there trying to make this work are using a Beagle Bone Black which is not what I have and also has on-board flash memory for the OS which I don't have.
Here is a long forum thread with a lot of clues about downloading the LXDE package and getting it to install. The scripts described from the "tools" directory seem to be on the Beagle Bone Black and not on the Ubuntu distro that I have. There's also some warnings about problems with Gnome utilities, which wouldn't affect me trying to install LXDE but I have Gnome in the Angstrom distribution and you never know when a customer is going to try to open something:
https://groups.google.com/forum/#!msg/beagleboard/TtcD9vfOzT8/1stwCBZqNRAJ
This link is mostly about BBB but is hopefully still instructional for my case:
http://elinux.org/Beagleboard:Installing_LXDE
A third option, c, is to try the BeagleBone distribution of Debian from the following link. There might be more of a chance that it will come up with a GUI desktop; BeagleBone's Angstrom distribution which had a GUI comes from the same page, and the Ubuntu distribution actually didn't come from any of BeagleBone's pages. Although reading the comments it seems that the latest Debian image from the BeagleBone page is corrupted so going down this path my end up sucking.
http://beagleboard.org/latest-images
However, when I tried it, the Debian image downloaded and booted fine and went to a GUI. It's a lot faster than Angstrom and looks nicer but doesn't have a lot of applications. It seems to be LXDE. It still doesn't have Tkinter, producing the exact same error message when I try to import it. Supposedly Debian is derived from Ubuntu or vice versa. So I launched into some more online searches:
Keying off of the specifics of the message:
Some search results from the message: File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 42:
This thread which describes the exact message, plus the "Package python-tk has no installation candidate" message I get when trying to do the installation: http://ubuntuforums.org/showthread.php?t=1959073A thread in which somebody solved the problem by installing the library using "Synaptic", and there's also some rage about why they wouldn't just include the library. Note that I don't seem to have Synaptic on my two working Beagle Bone distros: http://askubuntu.com/questions/513981/tkinter-on-ubuntu-14-04-seems-not-to-workA page about How to install Tkinter, however it doesn't seem to mention needing tk-dev as another search seems to have turned up: http://tkinter.unpythonic.net/wiki/How_to_install_Tkinter
Some search results from: E: Package 'python-tk' has no installation candidate:
A thread that describes what I'm seeing exactly, but no apparent solutions. A link to a python man page about Tkinter, some suggestions to check the repository list (which is probably my issue since I'm not even on a network)http://ubuntuforums.org/showthread.php?t=361342
The python wiki page mentioned above, which includes such interesting categories as "Tkinter Folklore"https://wiki.python.org/moin/TkInterAn interesting thread with a newbie in which it is eventually resolved that he's not getting to the mirrorshttp://ubuntuforums.org/showthread.php?t=1629083
Searching for Sneakernet options for doing package updates:
A thread full of different ideas, like using Synaptic, an offline repository program, apt-mirror, using apt-get with some kind of verbose arguments, and other hints: http://askubuntu.com/questions/974/how-can-i-install-software-or-packages-without-internet-offlineA short thread where somebody gives a link to Ubuntu's packages web page: http://ubuntuforums.org/showthread.php?t=1488395A hint which seems to be to run apt-get while navigated to the thumb drive, an interesting idea. Also mentions running dpkg: http://www.linuxquestions.org/questions/linux-newbie-8/install-new-packages-from-usb-drive-using-apt-get-4175417568/Another instructional about using dpkg: http://www.pendrivelinux.com/how-to-install-deb-packages/
So, in the end, I brought the board home and plugged it into my FiOS router with the Debian OS installed; it got a DHCP address immediately and got on the network with no issues. I began following the instructions for doing package updates for Ubuntu using apt-get, and they worked very smoothly. I had to do the following:
sudo apt-get update
sudo apt-get install python-tk
And that seemed to fix it! From within the python prompt, I was able to import Tkinter and launch dialog boxes like I plan to do with my final program. Apparently, rebuilding python as described in the Ubuntu links was not required.
After getting that to work, I was curious to see if I could get it to work for Angstrom. Angstrom doesn't seem to use apt-get, it uses opkg. I did
opkg update
opkg list | grep tkinter
opkg install tkinter
(I have to check that the last line is exactly the one that I did). Anyhow, it didn't work. I also tried:
opkg install tk-dev
It downloaded and installed, but still no love from "import Tkinter". I was unable to "rebuild" python according to the instructions in the one link that explained it because Make failed with some error message that didn't make any sense, and I couldn't find a "configure" script in the python lib directory. It is probably likely that I haven't actually downloaded the python source directory.
Rather than address that problem directly, I decided to turn back to getting a GUI for the Ubuntu distribution, now that I'd overcome my fear of putting the Beagle Bone on my home network and had gotten through a cycle or two of downloading and installing packages. One of the many web searches I'd done had shown some much nicer-looking Tcl/Tk dialog boxes for a Ubuntu desktop which makes sense since Tkinter uses whatever API is native to the OS. After some searching through links like the following:
http://www.makeuseof.com/tag/10-top-linux-desktop-environments-available/
http://www.javacodegeeks.com/2014/02/5-most-awesome-desktop-environments-for-ubuntu.html
I decided that the desktop I saw must have been the "Unity" desktop which is the one that is most often used with Ubuntu anyhow. It looks like this:
http://4.bp.blogspot.com/-K47RqgkByzA/TyqL0svW6oI/AAAAAAAAHmM/86rVanAbLtA/s1600/ubuntu-precise-apps-screenshot.png
So to get Unity, there seems to be a circle of links describing how to install it on an SD card for Beagle Bone. Some of these are for BBB which I don't have, and some talk about "expanding" the disk partition on the SD which again sounds like a lot of work. I guess I should try these though:
http://elinux.org/Beagleboard:Ubuntu_On_BeagleBone_Black#Ubuntu_Precise_On_Micro_SD
http://elinux.org/Beagleboard:Desktops_On_Ubuntu/Debian#Ubuntu_Precise_On_A_microSD_With_Ubuntu_Desktop
I'm not sure yet what the difference is between Unity and Precise. Unity is supposedly the default desktop, while the links mention Precise, and they both look the same in Google image searches.
Here's an instructible about installing Ubuntu with LXDE, presumably the procedure for installing Unity would be similar. Since I apparently already have LXDE with my Debian install, my interest is in trying to experiment with something visually different:
http://www.instructables.com/id/BeagleBone-Ubuntu-OS-LXDE-GUI/
