Hello
I need to interface 4MB of DRAM to a motorola DSP56364 and want to do it
as cheaply as possible with the minimal amount of components. My first
idea was to use an off the shelf (surplus) 4MB 30 pinn simm that you can
pick up for a few bucks. The socket takes up minimal PCB real estate.
The problem is they are 5V and the 56364 is 3.3V
Any suggestions on interfacing the two. What would happen if i ran the
simm from 3.3V?
Or is there another route i should be considering.
Maybe there is an off the shelf 4MB 3.3V dram chip i don't know about.
Thank you in advance for any suggestions and advice you can give.
Best regards
Scott
DRAM to DSP56364, best route?
Started by ●December 14, 2005
Reply by ●December 14, 20052005-12-14
Scott,
I believe the 56364 is 5v tollerant on the EMI interface. Also,
depending on the DRAM, most likely the DSP's output high voltage level
will be high enough for the DRAM to consider it a "1". So the interface
should be pretty easy. If I'm wrong on the 5v tolerance then all you
need are some simple voltage translation buffers...
--
dB
--- scott@scot... wrote:
> Hello
> I need to interface 4MB of DRAM to a motorola DSP56364 and want to do
> it
> as cheaply as possible with the minimal amount of components. My
> first
> idea was to use an off the shelf (surplus) 4MB 30 pinn simm that you
> can
> pick up for a few bucks. The socket takes up minimal PCB real estate.
>
> The problem is they are 5V and the 56364 is 3.3V
> Any suggestions on interfacing the two. What would happen if i ran
> the
> simm from 3.3V?
> Or is there another route i should be considering.
> Maybe there is an off the shelf 4MB 3.3V dram chip i don't know
> about.
> Thank you in advance for any suggestions and advice you can give.
> Best regards
> Scott
>
__________________________________________________
I believe the 56364 is 5v tollerant on the EMI interface. Also,
depending on the DRAM, most likely the DSP's output high voltage level
will be high enough for the DRAM to consider it a "1". So the interface
should be pretty easy. If I'm wrong on the 5v tolerance then all you
need are some simple voltage translation buffers...
--
dB
--- scott@scot... wrote:
> Hello
> I need to interface 4MB of DRAM to a motorola DSP56364 and want to do
> it
> as cheaply as possible with the minimal amount of components. My
> first
> idea was to use an off the shelf (surplus) 4MB 30 pinn simm that you
> can
> pick up for a few bucks. The socket takes up minimal PCB real estate.
>
> The problem is they are 5V and the 56364 is 3.3V
> Any suggestions on interfacing the two. What would happen if i ran
> the
> simm from 3.3V?
> Or is there another route i should be considering.
> Maybe there is an off the shelf 4MB 3.3V dram chip i don't know
> about.
> Thank you in advance for any suggestions and advice you can give.
> Best regards
> Scott
>
__________________________________________________
Reply by ●December 14, 20052005-12-14
Hi
According to the datasheet port A is not 5v tolerant.
In order to go down the simm route I would need to try one of the
following
1. run the sim at 3.3V
2. use level shifting logic
I would rather option 1 as it would be easier but I don't know about the
reliability???
The other option is using 3.3V dram. Anyone have recommendations?
Best regards
Scott
-----Original Message-----
From: dbaudiopro [mailto:dbaudiopro@dbau...]
Sent: 14 December 2005 18:16
To: scott incz; motoroladsp@moto...
Subject: Re: [motoroladsp] DRAM to DSP56364, best route?
Scott,
I believe the 56364 is 5v tollerant on the EMI interface. Also,
depending on the DRAM, most likely the DSP's output high voltage level
will be high enough for the DRAM to consider it a "1". So the interface
should be pretty easy. If I'm wrong on the 5v tolerance then all you
need are some simple voltage translation buffers...
--
dB
--- scott@scot... wrote:
> Hello
> I need to interface 4MB of DRAM to a motorola DSP56364 and want to do
> it as cheaply as possible with the minimal amount of components. My
> first idea was to use an off the shelf (surplus) 4MB 30 pinn simm that
> you can pick up for a few bucks. The socket takes up minimal PCB real
> estate.
>
> The problem is they are 5V and the 56364 is 3.3V Any suggestions on
> interfacing the two. What would happen if i ran the simm from 3.3V?
> Or is there another route i should be considering.
> Maybe there is an off the shelf 4MB 3.3V dram chip i don't know about.
> Thank you in advance for any suggestions and advice you can give.
> Best regards
> Scott
>
__________________________________________________
-------------
Check out our new 6 Band broadcast processor the 'DSPXtra' integrating the award winning 'Ariane' RMS leveller.
More information on our processors can be found at
http://www.broadcastwarehouse.com/search?searchtext=dspx
According to the datasheet port A is not 5v tolerant.
In order to go down the simm route I would need to try one of the
following
1. run the sim at 3.3V
2. use level shifting logic
I would rather option 1 as it would be easier but I don't know about the
reliability???
The other option is using 3.3V dram. Anyone have recommendations?
Best regards
Scott
-----Original Message-----
From: dbaudiopro [mailto:dbaudiopro@dbau...]
Sent: 14 December 2005 18:16
To: scott incz; motoroladsp@moto...
Subject: Re: [motoroladsp] DRAM to DSP56364, best route?
Scott,
I believe the 56364 is 5v tollerant on the EMI interface. Also,
depending on the DRAM, most likely the DSP's output high voltage level
will be high enough for the DRAM to consider it a "1". So the interface
should be pretty easy. If I'm wrong on the 5v tolerance then all you
need are some simple voltage translation buffers...
--
dB
--- scott@scot... wrote:
> Hello
> I need to interface 4MB of DRAM to a motorola DSP56364 and want to do
> it as cheaply as possible with the minimal amount of components. My
> first idea was to use an off the shelf (surplus) 4MB 30 pinn simm that
> you can pick up for a few bucks. The socket takes up minimal PCB real
> estate.
>
> The problem is they are 5V and the 56364 is 3.3V Any suggestions on
> interfacing the two. What would happen if i ran the simm from 3.3V?
> Or is there another route i should be considering.
> Maybe there is an off the shelf 4MB 3.3V dram chip i don't know about.
> Thank you in advance for any suggestions and advice you can give.
> Best regards
> Scott
>
__________________________________________________
-------------
Check out our new 6 Band broadcast processor the 'DSPXtra' integrating the award winning 'Ariane' RMS leveller.
More information on our processors can be found at
http://www.broadcastwarehouse.com/search?searchtext=dspx
Reply by ●January 9, 20062006-01-09
Hi Scott,
just in case that you haven't found a solution already:
The EMI of the '364 is not 5v tolerant. The cheapest solution to interface 5V peripherals is using a 74lvx245 bus transceiver for the 8-bit databus (you don't need level-shifting for outbound signals), supplied from the 3.3V power rail. This bus transceiver has 5V-tolerant inputs but adds a 5-7ns delay to the bus signals, which is usually no problem for 50-70ns DRAMS. Otherwise you could use a 74cb3t3245 lelvelshifter from TI, also inexpensive and with '245 pinout.
Regards,
Christian.
just in case that you haven't found a solution already:
The EMI of the '364 is not 5v tolerant. The cheapest solution to interface 5V peripherals is using a 74lvx245 bus transceiver for the 8-bit databus (you don't need level-shifting for outbound signals), supplied from the 3.3V power rail. This bus transceiver has 5V-tolerant inputs but adds a 5-7ns delay to the bus signals, which is usually no problem for 50-70ns DRAMS. Otherwise you could use a 74cb3t3245 lelvelshifter from TI, also inexpensive and with '245 pinout.
Regards,
Christian.
