External SRAM on uPSD3234

[danilo2399]

Posted on April 24, 2003 at 05:54

External SRAM on uPSD3234

[danilo2399]

Posted on May 17, 2011 at 11:53

Is there someone woking with external SRAM attached to the uPSD3234 ?.

I´m having some dificulties to understand how to make A12 to A15 lines available outside the uPSD chip.

[yu-jun]

Posted on May 17, 2011 at 11:53

if some addresses are not used In uPsd32××, you can use the remainder address to link other IC not affect the uPsd32××'s register.

[simonharrison9]

Posted on May 17, 2011 at 11:53

Hi,

You need to use PSD outputs, PB, PC etc

Configure a pin each for A12, A13, A14, A15 as chipselect, active high.

Then in the next part, Chip Select Equations, enter the signal for the chip select in the Logical AND box

example:

A12 , no start address, no end address, a12 in the Logical AND box

hope this helps

Simon

[ This message was edited by: sjh on 12-11-2003 16:20 ]

[joseph2399]

Posted on May 17, 2011 at 11:53

Address lines a12 - a15 used for the xRAM can be brought out externally by using ports pb0 - pb3 of the uPSD. Just set these pin to ''Combinatorial'' CPLD output, then write an I/O Logic equation for each of the a12-a15 pins, (e.g. a12_x=a12, a12 output enable=Vcc). After the *.obj is loaded to your uPSD, pb0 will become your address line, a

[irawan1]

Posted on May 17, 2011 at 11:53

Dear all,

Any hints how to protect external SRAM attached to uPSD in data retention mode (battery backup mode)?