SDRAM_CONFIG Register in AM3352

Hi GSR,

The information in this wiki is valid for all AM335X processors. There are also two other links which you will find useful:

http://processors.wiki.ti.com/index.php/AM335x_EMIF_Configuration_tips

http://processors.wiki.ti.com/index.php/Sitara_Linux_Training:_Tuning_the_DDR3_Timings_on_BeagleBoneBlack

Hi Biser,

Thank You for the reply.

The URL's are useful for SW Levelling and Calculating Initial Ratio Seed Values and Timing Values.

Still I do not find information related to some fields in the SDRAM_CONFIG register such as reg_ddr_term, reg_dyn_odt and reg_sdram_drive.

What about ZQ_CONFIG is it a constant value always which is nothing but 0x50074Be4

Regards,

GSR

for additional information see section 7.3.5.3 in the AM335X Technical Reference Manual Rev. J.

Hi,

I understand this old thread.

I referred the section 7.3.5.3, but it has description as following

For DDR3, set to 1 for RZQ/4, set to 2 for RZQ/2, set to 3 for RZQ/6, set to 4 for RZQ/12, and set to 5 for RZQ/8.

How do I know what value do I have to set in the TRM. In the DDR3 datasheet it is given that RZQ is 240 with 1% tolerance.

Also how do I have to decide what value needs to be used for Dynamic ODT, is it suppose to be RZQ/4 or RZQ / 2?

Best Regards,

GSR

The value selected should match your trace impedance. If traces are 50 Ohm, which is typical, use RZQ/4.

Hi Biser,

Thank You for your reply and the support.

So if trace impedance is 50 ohm then do we have to use the following values?

SDRAM_CONFIG.REG_DDR_TERM[26 : 24] = 1 (RZQ / 4)

SDRAM_CONFIG.REG_DYN_ODT[22 : 21] = 1 (RZQ / 4)

SDRAM_CONFIG.REG_SDRAM_DRIVE[19 : 18] = 0 (RZQ / 6)

Also how do we configure ZQ_CONFIG register is it always 0x50074BE4 for DDR3?

Thanks for your time.

Regards,

GSR

This thread: http://e2e.ti.com/support/arm/sitara_arm/f/791/t/395205 gives some more details. As for ZQ_CONFIG register, all register that are not mentioned in http://processors.wiki.ti.com/index.php/AM335x_EMIF_Configuration_tips and http://processors.wiki.ti.com/index.php/AM335x_DDR_PHY_register_configuration_for_DDR3 should be left at their default values.

Hi Biser,

Thanks for the reply.

I understand what you are saying, as ZQ_CONFIG register is not listed in the above URL, we shouldn't program this register.

But, why the  AM3358 StarterKit GEL File programming the ZQ_CONFIG (Offset: 0xC8) register with a value of 0x50074BE4?

Am, I missing anything.

Regards,

GSR

What I mean is that you should leave it as it is and not modify it.

Hi Biser,

Thanks for your reply.

I have one doubt we are using 2 DDR3 chips and total RAM size is 1 GB.

After entering into values in ratio seed, I see some strange value for WR DQS, can you check these values once? I had attached the RatioSeed_AM335x_boards.xls file. In this file we modified Customboard_DDR3 sheet.2821.RatioSeed_AM335x_boards.xls

Also in the following URL: processors.wiki.ti.com/index.php/AM335x_DDR_PHY_register_configuration_for_DDR3_using_Software_Leveling  it describes that we need to run CCS .out file to do software levelling. Can we run this file on our custom board also or else any modifications required for this .out file?

Thank You for your time.

Regards,

GSR

About the CK trace lengths, have you entered trace length from AM335X to DDR3 for each chip? The other thing you can try is using PHY_INVERT_CLKOUT=1.

About the .out file, the whole procedure and necessary modifications are described step-by-step here: http://processors.wiki.ti.com/index.php/Sitara_Linux_Training:_Tuning_the_DDR3_Timings_on_BeagleBoneBlack

Hi Biser,

Thanks for the reply.

I had gone through this URL. My doubt is under 

Configure the Development Environment --> Prerequisites it is given Executable CCS .out file DDR3_slave_ratio_search_auto.zip package.

To perform software levelling on our custom hardware (2 DDR3 chips and total capacity is 1 GB), do I need to modify the binary file inside this zip package?

Regards,

GSR

Please read the entire tutorial. The .out file will prompt you to enter values from the Excel chart and then should display converged values.