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Subject: Re: External Serial LCD Display / Keypad

Re: External Serial LCD Display / Keypad

From: BlueChip <>
Date: Fri, 06 Aug 2004 01:18:15 +0100

We have one readily available serial pin, but it can be toggled between Rx
and Tx.
This means that you will need to think carefully about the protocol you design.

Serial data can be driven at any voltage.
RS232, by example, uses -15V for a zero and +15V for a one.
This voltage can be easily generated with a Maxtium MAX232 chip and a
couple of pump capacitors.
TTL generally drives well at about 0/5V ...check the individual chip specs.

I too have debated the idea of a video output, TV-Out would be cool for
home use (along with a remote control.) Various PPUs are available to such
end, but you are very likely to need an external PSU to drive the unit whoch point, the voltage output by the jukebox is not relevant, as
you could drive a simple darlington-pair to step the voltage quite simply :)


>Hi all,
>I was curious to see if anybody has tried using
>Rockbox with an external LCD display...
>It would be really good if I could get it working - it
>has got some nice features - "General Purpose Output"
>connectors to control external devices, and more
>interesting - a keypad interface. This basically means
>that I could control my Archos remotely with a keypad.
>This is the model that I own from Matrix Orbital : -
>I am not scared of writing a small bit of C to
>interface to the LCD. However, I have a couple of
>1. The serial interface on the LCD requires 3 cables -
>Transmit, Receive and Ground. I believe that there is
>only one serial data line from the Archos - am I out
>of luck?
>2. The Archos only supplies 3v on this serial line
>from what I am led to believe. Is the normal serial
>voltage 5v? Will I need a small circuit to amplify
>this voltage?
>Thanks in advance,
>___________________________________________________________ALL-NEW Yahoo!
>Messenger - all new features - even more fun!

Received on 2004-08-06

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