EBI bus interface in MPC5777C controller

[shalakashinde]

Hi,

I have confusion on how to configure the data and address lines in EBI of MPC5777C controller.

I want to use Muxed-32 bit mode (with two 1Mx16 MRAM chips (20 address lines) and two 64Mx16 NOR Flash chips) with chip selects 0 and 1 for MRAM and NOR flash respectively.

As shown in the table above, Address [9:15] are dedicated address pins and functionality will always be address irrespective of mode settings.

D_ADD_DAT[0:15] pins are multiplexed for Add#ress[0:15] and Data[0:15].

First of all, in pin-out of the controller, this name is not mentioned on these pins and it is mentioned as D_DAT[0:15].

1. Are these pins really multiplexed? or only function is data?

2. If they are multiplexed with Address[0:15], then Address[9:15] is getting duplicated at two places.

Will it be generated at two set of pins?

3. Address[9:15] can also be configured as GPIOs.

If I do so, will address duplication affect the function of my GPIOs, in case answer to question 2 is yes?

Also,

how pins D_OE, D_WE0, D_WE1, D_WE2, D_WE3, D_RD_WR are supposed to be used for different chip selects?

Thanks,
Shalaka

[marcellobellini]

I already use this configuration with 32-bit bus and it works.
It work not on burst mode in my board

[davidtosenovjan]

1) Yes, it is marked confused way but these pins can works as D_ADD_DAT[0:15] in multiplexed mode. I will suggest documentation improvement.

2) These are duplicated but D_ADD[9:15] contains only address thus they may not be buffered.

3) Yes, you can use these pins as GPIO if you don’t need it for EBI purpose.

4) D_OE, D_WE0, D_WE1, D_WE2, D_WE3, D_RD_WR will be shared for all devices connected (if all used, flash memories typically don’t need all WE lines). Only CS lines distinguish between connected device.

[shalakashinde]

Thanks David.

I have one more question on this:

In 32-bit muxed mode, will ADD[9:15] be dedicated address lines? Will the address be valid throughout the write or read cycle?

I am basically latching only ADD_DAT[16:31] signals and connecting ADD[9:15] directly to memory to avoid using another latch for ADD_DAT[0:15] signals.

Will this work?

Thanks,

Shalaka

[davidtosenovjan]

Yes, it is correct.

[shalakashinde]

Thank you for the confirmation.