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How to connect slow peripheral to AD-Bus in mixed-voltage-designs?

Question asked by Stefan Opitz on May 2, 2014
Latest reply on Jun 25, 2014 by Fang Li

I´ve got the netburner module with Coldfire 54415 and i have to connect the TNT4882 Controller from NI.

 

This results in a mixed voltage design - Processor 3,3V, Peripherie 5 V.

 

I will use this one in a mode with 8-bit non-multiplexed AD- bus, /IRQ, /Reset, /CS, /RD and /WR signals.

 

My problems are:

a) What is a smart solution for generating /RD and /WR signal? My actual idea is, to generate these signals with NAND

74LVC132: /RD = !(!RD/WR & /CS), /WR = !(RD/WR & /CS)

b) I need a mixed-voltage driver for databus. An idea is 74LVC245A, but I cannot find a fitting signal for G (Enable).

c) Regarding contol-signals: I cannot interpret the timing of /BE[0..3]. Is it similar to /CS? Perhaps this one could fit.

 

Do You have a reference-design for connecting such a device in mixed-voltage-environments?

 

Thank You very much in advice,

Stefan

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