AM335x Nand timing optimization

Wonjae Chang

Prodigy 80 points

Hi all,

now I'm trying to optimizing my am335x custom board.

my nand flash chip product name is TC58NVG1S3HTA00

there is one thing I wonder.

there is the register field called RWACCESSTIME / WRACCESSTIME on GPMC_CONFIG5 AND GPMC_CONFIG6.

My board not use attached memory device.

Then, could I don't care about the WRACCESSTIME field?

WRACCESSTIME field is explained Delay from StartAccessTime to the GPMC_FCLK rising edged used by the attached memory for the first data capture.

My board doesn't use GPMC_CLK, only use GPMC_FCLK.

If anyone knows about this issue please let me know.

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

All bitfields in the GPMC configuration registers must be filled in correctly for proper operation of the interface.

0 Wonjae Chang over 9 years ago in reply to Biser Gatchev-XID

Prodigy 80 points

Then, if I don't use any other attached memory device and GPMC_CLK, could I set 0 in that field?

Thanks,
Wonjae

0 Biser Gatchev-XID over 9 years ago in reply to Wonjae Chang

TI__Guru**** 393215 points

I suggest you set it to the value required by the NAND device even if you will not write to the memory.

0 Wonjae Chang over 9 years ago in reply to Biser Gatchev-XID

Prodigy 80 points

then what should i do if I cannot find about the exact value of WRACCESSTIME value.
would you please explain about that field?
I already read TRM of AM335x but I can get clearly about that field

Best Regards,
Wonjae

0 Biser Gatchev-XID over 9 years ago in reply to Wonjae Chang

TI__Guru**** 393215 points

Read the whole section 7.1.3.3.12 in the AM335X TRM Rev. L.

0 Wonjae Chang over 9 years ago in reply to Biser Gatchev-XID

Prodigy 80 points

Actually I already read that part.. but I didn't get exact concept about it.
Would you mind explain about it?

0 Biser Gatchev-XID over 9 years ago in reply to Wonjae Chang

TI__Guru**** 393215 points

NAND memories have a specific access protocol. They are accessed through the data lines only. For example, to read data from the NAND you have to issue a read command, typically followed by the read address. Both of these are written to the NAND, so there is no way you can control the NAND without programming the write timings. You have to take the write access time from the NAND datasheet and program the GPMC accordingly.

0 Wonjae Chang over 9 years ago in reply to Biser Gatchev-XID

Prodigy 80 points

The problem is no where I can find the value of access time. For example, there is the value of Read Access time max 20.
but I can't find the value of write access time.
It could be possible the value of Write access time same with Read access time?
Even in AM335x TRM, there is no diagram about write access time.
If you know where is it in TRM would you mind let me know?

Best Regards,
Wonjae

0 Biser Gatchev-XID over 9 years ago in reply to Wonjae Chang

TI__Guru**** 393215 points

See sections 7.1.3.3.12.1.3 and 7.1.3.3.12.1.4 in the AM335X TRM Rev. L. There should be similar timing diagrams in your NAND datasheet.

0 Wonjae Chang over 9 years ago in reply to Biser Gatchev-XID

Prodigy 80 points

I also know about that diagram, but there is no information about WRACCESSTIME.
In your opinion what WRACCESSTIME value in that diagram?

Best Regards,
Wonjae

0 Biser Gatchev-XID over 9 years ago in reply to Wonjae Chang

TI__Guru**** 393215 points

See section 7.1.3.3.9.8 and subsections under it for definition of RDACCESSTIME and WRACCESSTIME.

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AM335x Nand timing optimization