[En-Nut-Discussion] ethernut board 3.1 LCD support

Paul Govers p.govers at triple-it.nl
Wed May 12 09:12:16 CEST 2010

Hi Ulrich,

Thats a good reminder that most of the IO is not 5volt tolerant!
Iam happy that i yesterday have not read from the Dispay :-) 
I succeeded to control the display in 4-bit mode, yesterday only one
character but the rest would be simple!

I will have a look at the CPLD, because i want to read the display to
know if the LCD is busy or not and i will take a look at level-shifters

Does someone know ready for use/Plug and play level-shifters? (maybe a
good product for in the egnite webshop!)


Met vriendelijke groet / with kind regards,

Paul Govers

-----Original Message-----
From: en-nut-discussion-bounces at egnite.de
[mailto:en-nut-discussion-bounces at egnite.de] On Behalf Of Ulrich Prinz
Sent: Tuesday, May 11, 2010 7:55 PM
To: Ethernut User Chat (English)
Subject: Re: [En-Nut-Discussion] ethernut board 3.1 LCD support

Hi Paul!

Am 11.05.2010 10:30, schrieb Paul Govers:
> Hi Ulrich,
> Thats great that you working on an LCD driver for the ethernut 3.1
> i will try tonight to get my LCD display working with my Ethernut 3.1
> i have read the documentatie about the HD44780 and it seems not to
I replaced the driver for AT91, it is not specialized on the EN 3.1 but 
it should work with all AT91 devices.
It uses GPIO for all signals and, in this release, will not support 
reading from the display. And this is something you might want, as the 
CPU on the EN 3.1 has no 5V tolerant pins. Reading without 
level-shifters will destroy the CPU if the display is driven with 5V. On

the other hand you might use the CPLD as a level shifter, it is 5V 
tolerant even driven with 3.3V or less.

I think I don't have time tonight for checking in my driver, but I will 
do it tomorrow night for sure. I actually think for adding another 
access method, the memory interface. I didn't check the data sheets of 
all AT91 if they can be programmed for such slow memories and if they 
are able to drive an active-high chip select.

Best regards, Ulrich

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