AM335x VREF_CTRL Register

g.f.

Guru 15520 points

Hi,

I have a question about DDR_VREF and VREF_CTRL Register of AM335x Control module.

I saw the following TI wiki and have questions.

processors.wiki.ti.com/.../AM335x_EMIF_Configuration_tips

1. Is external circuit for DDR_VREF required and must VREF_CTRL value always be 0x00000000?

If answer of question #1 is Yes,

2.What is VREF_CTRL register for?

If answer of question #1 is NO,

3.Can the customer use the VREF_CTRL register for DDR_VREF without external circuit?

best regards,

g.f.

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

Hi g.f,

An external reference voltage on DDR_VREF pin is always required, except for LPDDR. Please check the reference schematics in section 7.7.2 of the AM335X Datasheet Rev.H. Register VREF_CTRL value should be left as recommended in the wiki page you refer.

0 g.f. over 10 years ago in reply to Biser Gatchev-XID

Guru 15520 points

Hi Biser,

Thank you for the reply.
I understood that DDR_VREF is required and VREF_CTRL value must be 0x00000000(recommended in the wiki page).
So, what is VREF_CTRL register for?

best regards,
g.f.

0 Biser Gatchev-XID over 10 years ago in reply to g.f.

TI__Guru**** 393215 points

It's part of the EMIF, but is not used in this device.

0 g.f. over 10 years ago in reply to Biser Gatchev-XID

Guru 15520 points

Hi Biser,

Thank you for the reply.

I'm sorry but let me ask again because my customer are setting this VREF_CTL register.
So, setting the value except 0x00000000 to VREF_CTL have no meaning and doesn't affect to device operation , is it correct?

best regards,
g.f.

0 Biser Gatchev-XID over 10 years ago in reply to g.f.

TI__Guru**** 393215 points

Please ask them to follow the wiki recommendations.

0 g.f. over 10 years ago in reply to Biser Gatchev-XID

Guru 15520 points

Hi Biser,

Okay , thank you.

best regards,
g.f.

Processors

Processors forum

AM335x VREF_CTRL Register