AM335x: few questions for adding a nand device.

Manuel Martinez Guillen1

Hi,

We still working in our custom design based on the schematics of the starter Kit. We need some support for adding an async 8bit 3.3V nand flash.

1. For the rail VDDSHV1: Can we use any 3.3V LDO of the TPS65910A3 (VMMC, VAUX2, VAUX33)? We've thought in using VMMC.

2. For nand booting (config bits):

A. CLKOUT no matter. Am I wrong?

B. We don't understand the difference between the ECC handled by processor or by the nand?. We'll use the following nand or equivalent:

http://www.hynix.com/datasheet/pdf/flash/HY27UF(08_16)4G2B%20(Rev0.4).pdf

Thanks,

Manuel.

over 12 years ago

0 Biser Gatchev-XID over 12 years ago

TI__Guru**** 393215 points

Hi Manuel,

1. You can use each of the LDO's you listed, just take care that you don't exceed the LDO rated current.

2A. Yes, this is correct, but anyway you should tie SYSBOOT5 to GND if you don't need CLKOUT1.

2B. I don't have an answer for this, perhaps someone else will join and answer.

Please note that there is a new AM335X datasheet on the TI product page, as of yesterday.

0 Manuel Martinez Guillen1 over 12 years ago in reply to Biser Gatchev-XID

Intellectual 270 points

Thanks by your quick response.

1. This is what worries me. I don't want to use VAUX33 since this LDO sources the VTT regulator (theorically peaks upto >0.5A if all the resistors would sink at time). We have a beaglebone but no a starter kit so can't we measure what LDO sources more current: VAUX2 or VMMC. On any case I just see that only one LDO sources all VDDSHVx rails with 200mA in the beaglebone, so I think VMMC should source from VDDSHV1 to VDDSHV5 with 300mA even suppliying also about extra 30mA for the nand device.

2A. Ok.

2B. We'll wait for someone else give us a hint.

Regards,

Manuel.

0 Biser Gatchev-XID over 12 years ago in reply to Manuel Martinez Guillen1

TI__Guru**** 393215 points

Hi Manuel,

Do you plan to use an SD Card? If not, VMMC should have enough power for your needs.

0 Manuel Martinez Guillen1 over 12 years ago in reply to Biser Gatchev-XID

Intellectual 270 points

Biser,

Yes: there's an SD socket installed. Do you recommend me to use VAUX2 (only supplies VDDSHV6: LCD&MCASP0&UARTS&SPIOs etc. ) instead of VMMC?. I'm in time to redo the routing.

Manuel.

0 Biser Gatchev-XID over 12 years ago in reply to Manuel Martinez Guillen1

TI__Guru**** 393215 points

Hi Manuel,

My concern was that some SD cards can draw quite high current during write operations. Yes, you could use VAUX2. The absolute max. current for VDDSHV6 is 100mA according to datasheet (real current should be quite lower), and VAUX2 can provide up to 150mA continuous current.

0 Manuel Martinez Guillen1 over 12 years ago in reply to Biser Gatchev-XID

Intellectual 270 points

Thanks a lot Biser,

awesome: TI's support is like a chat: it takes 5 minutes to get an answer :-).

Best regards.

Manuel.

0 Biser Gatchev-XID over 12 years ago in reply to Manuel Martinez Guillen1

TI__Guru**** 393215 points

Thanks for the kind words Manuel. As to 5 minutes, that's as long as we are in near time zones :)

0 Manuel Martinez Guillen1 over 12 years ago in reply to Biser Gatchev-XID

Intellectual 270 points

I found this wiki:

http://processors.wiki.ti.com/index.php/Raw_NAND_ECC

It doesn't mention anything about the AM335x but I can guess that since the AM335x doesn't support 1bit ROM ECC and the nand we will install has internal 1bit ECC (also the datasshet doesn't recommend even 2 external ECC: is an old part) we will have problems if we try to boot with ROM ECC.

On any case I will let the chance to override the config bit.

Best regards,

Manuel.

0 Biser Gatchev-XID over 12 years ago in reply to Manuel Martinez Guillen1

TI__Guru**** 393215 points

Hi Manuel,

I agree, it will be best if you are able to configure SYSBOOT9 either high or low.

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AM335x: few questions for adding a nand device.