PIN multiplexing in LPC

painofab — Thu, 30 Jun 2011 16:04:53 GMT

Hello everybody,

I'm supporting our hardware engineer for our design which uses MPC5125, and we are dealing with the LPC (Local Plus Bus Controller).

We need to connect 8 peripherals on this bus, and some of them are 128 MByte Flash memories, so we need this bus configuration:

Data Bus: 16 bit
Address Bus: 26 bit (probably short-addressing mode, but may also be byte-addressing mode)

I saw that there are 8 Chip Select signals (CSx), but some of them are multiplexed with the LPC Address Signals, so only a subset is really available.

Does anybody know how many Chip Select signals are available in this configuration (16 + 26)?

I also noticed that the CS0 signal, which carries the information about the boot device, is multiplexed with the ACK/BURST signal, do you know if the LPC works properly even without the ACK/BURST signal?

We are using NOR Flash devices, so we can't use the NAND Flash Controller, which could be very useful in this case, but this choice is out of my scope!

Thanks in advance to everybody who could help me on this matter.

Regards,

Fabrizio

Re: PIN multiplexing in LPC

TomE — Fri, 01 Jul 2011 12:12:47 GMT

You may need to use external address decoders to "fan out" one or more of the chip-selects.

Tom

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PIN multiplexing in LPC

Re: PIN multiplexing in LPC