Behavior of AM335x GPMC_BEn1 during XIP(MUX2) non-muxed 8 bit boot

g.f.

Hi,

I have a question about AM335x GPMC_BEn1 during XIP non-muxed(MUX2) 8-bit boot mode.

At my customer board, NOR Flash are connected to GPMC_CSn0 for XIP boot.
And other memory are connected to GPMC_CSn2.

As written in TRM(spruh73m) page.4930 Table 26-9, I understood that
GPMC_CSn2 and GPMC_BEn1 terminals are driven in MUX2 mode with the BE1N signal.

In 8-bit memory access I guess GPMC_BEn1 won't be used,
so we are thinking that this caution can be ignored as far as 8bit boot XIP boot mode are used
if GPMC_CSn2 will be driven to High during XIP 8-bit boot mode.

Does GPMC_CSn2 will be driven to High during XIP non-muxed(MUX2) 8-bit boot?
Or is it unknown state and need to take care the GPMC_CSn2 during boot?

best regards,
g.f.

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi g.f,

In my opinion it would be best to move GPMC_CSn2 to another GPMC CS signal, or isolate it at boot time, as unpredictable behavior could prevent the board from booting properly.

0 g.f. over 9 years ago in reply to Biser Gatchev-XID

Guru 15520 points

Hi Biser,

Thank you for the reply.

My opinion is same as you.
But I need to answer to my customer about GPMC_CSn2 state during non-muxed 8bit XIP(MUX) boot.
Can I answer as that GPMC_CSn2 might be in unknown state?

best regards,
g.f.

0 Biser Gatchev-XID over 9 years ago in reply to g.f.

TI__Guru**** 393215 points

In XIP non-muxed(MUX2) boot mode GPMC_CSn2 will be configured in muxmode 1 (as GPMC_BEn1) by ROM code, and it could be driven by ROM code software regardless of 8-bit mode being selected. In my opinion this is what you should answer to your customer.

0 g.f. over 9 years ago in reply to Biser Gatchev-XID

Guru 15520 points

Thank you for the reply.
I uderstood.

best regards,
g.f.

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Behavior of AM335x GPMC_BEn1 during XIP(MUX2) non-muxed 8 bit boot