LCD-dsp interface timing

Hi there

i have to interface an lcd (hitachi HD44780 based controller) to a dsp
(tms320c6713b from ti).
the problem is that the lcd controller is very slow in accepting data.
in order not to use too much of the dsp resources, i don't want to
introduce any wait states in the dsp.
other peripherals are also connected to the emif, so i don't want to
slow down the emif either.
has anyone an idea how to interface the lcd with the dsp?

thanks a lot for any suggestions, you'd help me a lot. 


gnoemli

gnoemli@gmail.com wrote:

> Hi there
> 
> i have to interface an lcd (hitachi HD44780 based controller) to a dsp
> (tms320c6713b from ti).
> the problem is that the lcd controller is very slow in accepting data.
> in order not to use too much of the dsp resources, i don't want to
> introduce any wait states in the dsp.
> other peripherals are also connected to the emif, so i don't want to
> slow down the emif either.
> has anyone an idea how to interface the lcd with the dsp?
> 
> thanks a lot for any suggestions, you'd help me a lot. 

Yes, how about a latch between ? This could be a 74HC574
parallel latch or a 74HC595 with built-in shift register.

Rene
-- 
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Hi gnoemli,

yes correct, the HD44780 is a nightmare regarding its timing. Most people
use software based delay routines between writes to the HD44780. However,
the most efficient way of talking to the HD44780 is to read back the control
register of the controller after having written anything to the
date/controlregister. As long as the highest bit is set the controller is
busy with the last character / function. Unfortunately the controller has no
hardware pin to signal this information, so you will have to make yourself a
routine that checks the controller say every 1 millisecond or so for being
ready.

regards
Ulrich

<gnoemli@gmail.com> schrieb im Newsbeitrag
news:1152860741.677531.42510@p79g2000cwp.googlegroups.com...
> Hi there
>
> i have to interface an lcd (hitachi HD44780 based controller) to a dsp
> (tms320c6713b from ti).
> the problem is that the lcd controller is very slow in accepting data.
> in order not to use too much of the dsp resources, i don't want to
> introduce any wait states in the dsp.
> other peripherals are also connected to the emif, so i don't want to
> slow down the emif either.
> has anyone an idea how to interface the lcd with the dsp?
>
> thanks a lot for any suggestions, you'd help me a lot.
>
>
> gnoemli
>