Hi Steve,
I have the same problem with my BBB and 4DCAPE-70T. Initially my BBB came
with Debian 3.8.13 bone47. I have a GUI program that I developed on a PC
and then moved it to the BBB where it worked fine with the 4DCAPE, no
errors at all. The GUI has a animated graph along with buttons and text
entry and display boxes. However I was trying to use the Adafruit BBIO for
a PWM output and ADC inputs and was having trouble getting that to work, so
I installed newer Debian distros and now am using the Debian 3.8.13 bone50
distro. Now I cannot run the simplest graph such as shown by Sendex
(https://pythonprogramming.net/matplotlib-intro-tutorial/), getting the tcl
no $DISPLAY error like you.
I don't know if the newer distro is the problem or possibly I am making
some mistakes in the installation of matplotlib etc.
Have you figured out a solution to the no $DISPLAY error?
I haven't tried connecting a keyboard and mouse to the BBB, since the BBB
and 4DCAPE once worked fine without the kbd and mouse attached but I will
do so now.
Please let me know if you have a solution.
Thanks,
John
On Saturday, May 23, 2015 at 2:31:43 PM UTC-7, Steve Plant wrote:
>
> Hi all,
>
> First off, I'm a newbe to the BBB, and more familiar with electronic
> hardware than software programming but thought I would give it a go.
>
> I have a BBB which I have updated with the latest Software
> BBB-eMMC-flasher-debian-7.8-lxde-4gb-armhf-2015-03-01-4gb.img.xz
>
> I would like to develop an application on the BBB with a 4D Systems 4.3"
> LCD Cape. Part number 4DCAPE-43T which will run a simple GUI to control a
> VSD and motor.
>
> Having connected the display which works perfectly, and downloaded the USB
> drivers I'm able to connect to the BBB and view its webpage. Found the IDE
> which is loaded onto the Debian image called Cloud9 and decided to give
> this a go.
> All was going well, using the example python programs, making changes and
> by simply hitting the RUN button it would flash LED's on the GPIO ports etc
> - no problem I thought "this is the easiest development board I have played
> with in a long while"
>
> I began to read up on a suitable GUI to use and for starters decided to
> try TKinter. having downloaded a few sample pieces of code I have hit a
> problem.
>
> If I try to run any code from Cloud9 which references TKinter, it will
> come up with the following problem, I have copied the sample code as well.
>
> Program******************************************
>
> import Tkinter as tk
>
> counter = 0
> def counter_label(label):
> counter = 0
> def count():
> global counter
> counter += 1
> label.config(text=str(counter))
> label.after(1000, count)
> count()
>
>
> root = tk.Tk()
> root.title("Counting Seconds")
> label = tk.Label(root, fg="dark green")
> label.pack()
> counter_label(label)
> button = tk.Button(root, text='Stop', width=25, command=root.destroy)
> button.pack()
> root.mainloop()
>
>
> Cload9 terminal output******************************
>
> Traceback (most recent call last):
> File "/var/lib/cloud9/examples/blink.py", line 14, in <module>
> root = tk.Tk()
> File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1712, in __init__
> self.tk = _tkinter.create(screenName, baseName, className,
> interactive, wantobjects, useTk, sync, use)
> _tkinter.TclError: no display name and no $DISPLAY environment variable
>
>
> I have found a work around, which is to write the code in Cloud9 as usual,
> it will flash up that it has saved all the changes automatically, then
> using a keyboard plugged directly into the BBB and a terminal open on the
> LCD cape, I can run the code directly on the BBB and it will work fine.
> If I have to, I will continue to develop my project like this, as I've had
> to do much worst in the past on other boards!! but I'm sure that there must
> be an easy fix to this so I don't need the extra keyboard attached to the
> BBB. it would also increase my "code/run/fix" cycle.
>
>
> Another option would be to develop directly on the BBB. Can I run a HDMI
> monitor from the BBB at the same time as the LCD cape? (its too small a
> screen to develop anything on the LCD cape itself)
>
> Any help would be much appreciated
>
>
> Steve.
>
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