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Re: Connecting IO to the devel boards



Perhaps you can use one of the parallel ports as an 
"address bus" to select a group of 8 I/O and the other as 
"data bus" ?
(Every "address" must select either input or output pins)

/Johan

----- Original Message ----- 
From: Mikael Starvik <starvik@xxxxxxx.com>
To: 'Bart Duchesne' <bduc@xxxxxxx.com>
Sent: Thursday, March 08, 2001 08:10
Subject: RE: Connecting IO to the devel boards


> Hi!
> 
> What performance do you need? If you need high
> performance it would be better to connect the FPGA
> to extern DMA and have a simple decoder in the FPGA.
> 
> It is simple to get 16 IO pins using the data bits on the 
> parallel ports. 16 additional bits is available on port
> A and B (if not used is some other way). Then there are
> some pins that can be used if the interface is not used
> (such as the pins for serial port 2 and 3). If some of
> your pins can be dedicated as input or output you can 
> find ever more available pins. In most applications
> you can get 40-50 IO pins from Etrax to an external
> device.
> 
> Best Regards
> /Mikael
> 
> -----Original Message-----
> From: owner-dev-etrax@xxxxxxx.com]On">mailto:owner-dev-etrax@xxxxxxx.com]On
> Behalf Of Bart Duchesne
> Sent: Wednesday, March 07, 2001 1:58 PM
> To: dev-etrax
> Subject: Connecting IO to the devel boards
> 
> 
> Hi guys,
> 
> I have the ETRAX development board her before me and I want to connect
> alot of IO to it.
> 
> I only need digital IO on a TTL level (between 48 and 96 bits or more). 
> (the final output drivers are allready present on other boards)
> 
> Ideally I would like to build this system around a single FPGA : one
> FPGA chip to the parallel ports of the etrax and a lot of IO with little
> routing. (I have no FPGA experience at this moment, are there FPGA's
> that are in PLCC package so that routing and experimenting with them is
> easy ? Tools ? )
> 
> Another alternative is to use a couple of 8255 and connect them with a
> little bit of glue logic to the etrax parallel ports (complexer design
> for routing)
> 
> Does anyone have any other ideas or comment ?
> 
> 
> 
> -- 
> 
> regards,
> 
> Bart Duchesne
> Dynamic Data Consulting BVBA
> Gijmelbergstraat 19
> B - 3201 Landorp
> 
> bduc@xxxxxxx.com
> Tel + 32 16 57 25 79
> Fax + 32 16 57 25 81
>