20x2 using A.0 for output to LCD

[smeagol]

Hi all,

Using a 20X2 for a project with the standard download circuit, using AXE027 download cable.

I need to send output to an LCD using AXE132 Serial LCD driver.

Are there any problems with using A.0, the SEROUT pin, to send data to the AXE132?

When the programming cable is disconnected I can see no problems as A.0 is normally left floating.

When the programming cable is connected am I likely to disrupt the download, or send rubbish to the LCD?

Cheers Gavin

 

[nick12ab]

I've tested it properly and when downloading a program, the OLED display fills with mean symbols (x&#773.



ADDED: I used the AXE033 rather than the AXE133 (I don't have any of those yet) so identical behaviour might not occur on the AXE133.

 

[smeagol]

So I just need to ensure the program clears the display at the start, something like:

Pause 500
serout A.0, N2400,(254,1)
Pause 30


Cheers

 

[Captain Haddock]

I've had both oled and lcd connected to A.0 on a 20x2 with no problems, the screen prints a load of gibberish when downloading but doesn't affect the operation at all, just make sure the first thing the prog does is clear the screen.

 

[nick12ab]

So I just need to ensure the program clears the display at the start, something like:

Pause 500
serout A.0, N2400,(254,1)
Pause 30


Cheers

Yes,

or

if the program immediately displays text on the entire display at the beginning of the program, this will overwrite it without requiring the screen to be cleared.

No clear required example:

    serout B.0,N2400,(254,128,"   Welcome to   ")
    serout B.0,N2400,(254,192,"  Winstar OLED  ")

Clear required example:

    serout B.0,N2400,(254,131,"Welcome to")
    serout B.0,N2400,(254,194,"Winstar OLED")

 

[hippy]

So I just need to ensure the program clears the display at the start

It depends. You may get lucky but the state the LCD / OLED / Driver is in will depend on what it has previously received and that could be 'anything' during the download.

You should ideally issue a full reset and configuration sequence to the LCD / OLED so you know you are in a known state.