Displayotron 3000 no text


#1

I recently bought a displayotron. Yesterday I downloaded the software via the Learn portal. Every thing loaded ok but none of the example software that included text worked. The examples to change the backlight do work.
I’m using a Rpi 2.
Any help would be much appreciated because I’m a complete novice on the software front!
Thanks in advance for all (any) replies.
Regards
John Wiggins


#2

When you say they don’t work, what happens - do you receive errors or the disolay simply stays blank?

… I assume that by downloading the software from the learn portal you mean, you have used the one-line installer as indicated in the getting started article?


#3

Hi
Yes I used the one line installer.
No text appears on the display.
I’ll fire up the RPi and see what message appears on the monitor when the program stops running, which is almost immediately after i have run it.

John


#4

Could be that the text is being printed but the contrast hasn’t been set. Or the buffer is not updated. Either way, please post the code, or at least the example you are running.


#5

When I run the program ‘hello_world.py’ nothing appears on the LCD.
On the monitor, when I run the program it says 'this example shows a basic “Hello World” on the LCD. You should see "Hello World " displayed on your LCD!

Press CTRL+c to exit.

But it exits the program straight away without pressing CTRL+c.

John


#6

Hi I’m back!
Just reinstalled the displayotron software.
Hey presto it works…almost!
The text is only just visible and the H of Hello is not appearing!?

John


#7

Yes, the ‘missing’ front of text is a recurrent issue. I’ve been meaning to look where it would be best to address (technically it should be in the parent library controlling the display chip itself, but it is used in several products, so care needs to be observed).

Anyhow, try adding time.sleep(0.1) just after you call the lcd.clear() method, that should cure it.

For your other issue, that is highly dependent on the lighting condition. See the API reference doc and the lcd.set_contrast(val) method specifically.


#8

Thanks for your very quick response.

Regards
John