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> From: Rafael Coello Paria <larisac@MAIL.COSAPIDATA.COM.PE>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: ISD CHIP AND OPTREX DMF50140 LCD HELP
> Date: Wednesday, May 28, 1997 9:43 AM
>
> Hi ,
>         This is the fisrt time I use this but I've been following some
time. I
> finally receive a PIC START PLUS and want to convert some code from PC
asm
> to PIC asm, its about driving a ISD25120 sound chip, .....

We just completed a project with the ISD2590.  We use the '44 driving shift
registers which address the ISD chip and then use a Philips amplifier
(TDA7052?) to drive a speaker.  We had difficulty at first with the PD pin
(popping) and finally got information from ISD that the chip does not
behave like the old ISD series.  We struggled for a while then we worked
the bugs out.  We also use PWM for the volume control and make sure the
volume is down before we address the chip and then turn the volume up.  We
are using it to play back 1 of 65 messages and not  the fast forward modes
as you describe.  One word of caution, if you cannot guarantee a good power
up reset, you might consider a recording of "nothing" at address 00000000
and then an EOM at 000000xx so the chip will accidently play nothing and
then see the EOM and stop.  We struggled with the reset issue and was
forced to add a pull-up capacitor to yank on a pin with VCC rise.

Craig R. Autio
cautio@equinox.shaysnet.com