topic Re: i.MX1060 SDRAM issue in i.MX RT Crossover MCUs

i.MX1060 SDRAM issue

donghua_chen — Tue, 02 Feb 2021 04:52:21 GMT

Hello,

I want to change the setting of “DLL delay chain clock“.

In Rev 1 of the IMXRT1060RM, this can be done via DLLSEL and DQSSEL field of MCR register.

However, they are removed from Rev 2 of the reference manual.

Please advise where we can set SDRAM read clock source to “DLL delay chain clock” and add more delay? thanks !

Re: i.MX1060 SDRAM issue

jeremyzhou — Tue, 02 Feb 2021 05:59:27 GMT

Hi,

Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
1) However, they are removed from Rev 2 of the reference manual.
Please advise where we can set the SDRAM read clock source to “DLL delay chain clock” and add more delay? thanks!
-- Actually, the SEMC module doesn't contain the DLLSEL and DQSSEL bits area, so they're removed in the updated version of RM.
Hope this is clear.
Have a great day,
TIC

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Re: i.MX1060 SDRAM issue

donghua_chen — Tue, 02 Feb 2021 06:13:45 GMT

Hi jeremyzhou,

Thank you for your quick reply.

if so, how to add more delay?

Re: i.MX1060 SDRAM issue

donghua_chen — Wed, 03 Feb 2021 06:29:01 GMT

Hello,

Would like to check when DSQ mode (DSQMD=1) is configured to loopback from DSQ pad (B7) shown below,

Is capacitor C76 meant to control the read strobe delay?
What is the formula to calculate the delay?

Re: i.MX1060 SDRAM issue

jeremyzhou — Wed, 03 Feb 2021 07:10:46 GMT

Hi,
Thanks for your reply.
1) Please check the datasheet to figure the impact of DSQ mode on the SEMC timing specification.
1) How to add more delay?
-- What kind of delay or time do you want to add?
Have a great day,
TIC

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Re: i.MX1060 SDRAM issue

donghua_chen — Thu, 18 Feb 2021 06:39:38 GMT

Hi,

We are looking at delaying of DQS similar to FlexSPI input operation shown 1.jpg.

For SEMC/SDRAM input operation, the datasheet only specified the data input setup and hold time. It does not mentioned how to configure the delay of DQS. I cannot find any text on the capacitor connected to the DQS pad.

Please point me to the right paragraph that explain how the capacitor works when DQSMD = 0x01.

We hope to add delay of 1 to 3 ns to SEMC_DQS by using the right value of capacitor.

thanks !

Re: i.MX1060 SDRAM issue

jeremyzhou — Thu, 18 Feb 2021 10:00:13 GMT

Hi,
Thanks for your reply.
Actually, NXP recommends Flexspi_DQS and SEMC_DQS pads both be floating and do not used for other functions if external memory has not this DQS dedicated pin, and it's useless to connect the capacitor to the DQS pad of the above memory chip to add the delay time.
So I think you'd better refer to the datasheet of the external memory which has the DQS pin if you want to try to add the delay time, it may provide some guides to make it.
Have a great day,
TIC

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Re: i.MX1060 SDRAM issue

donghua_chen — Fri, 19 Feb 2021 04:05:07 GMT

Hi,

Our design and SDRAM selection were done based on the design of NXP RT1060 EVB. Both SDRAM from ISSI and Winbond selected by NXP do not have DQS pin.

When DQS pin of i.MX RT1060 is recommended to be left floating, please confirm DQSMD should be set to 0x1 or 0x0?

We need to check the TIS spec accordingly. When DQSMD = 0x0, TIS of 8.67ns (> Tclk166mHz 6.01ns) does not make sense.

Re: i.MX1060 SDRAM issue

jeremyzhou — Fri, 19 Feb 2021 08:42:46 GMT

Hi,

Thanks for your reply.
1) When DQS pin of i.MX RT1060 is recommended to be left floating, please confirm DQSMD should be set to 0x1 or 0x0?
-- You can set the DQSMD to 0x01 to achieve the maximum speed.
Have a great day,
TIC

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Re: i.MX1060 SDRAM issue

donghua_chen — Mon, 22 Feb 2021 03:46:25 GMT

Hi,

Setting DQSMD to 0x01 will not work with our design using the Winbond SDRAM at all. Note that the same SDRAM was also used in i.MX RT106F vision solution.

About 8-10 months back, it was NXP FAE who told us to set DQSMD to 0x0 when we first tried to turn on this Winbond SDRAM.

Lastly, please comment that on TIS of 8.67ns when DQSMD is set 0x0. How will 8.67ns work with Tac (5 to 5.4ns) of any SDRAM in CAS 3 read operation?

The timings do not tally on paper but it worked with Winbond SDRAM when DQSMD is set to 0x0.

Re: i.MX1060 SDRAM issue

jeremyzhou — Mon, 22 Feb 2021 06:49:00 GMT

Hi,
Thanks for your reply.
TIS is used to demonstrate the input timing, so it's not fit for reading operation actually (as Fig 1 shows).

Fig 1

In further, after checking, the pins of W9825G6JB-6I is almost compatible with IS42S16160J-6BLI, and the SEMC can access the IS42S16160J-6BLI successful when DQSMD is set to 0x1, maybe you can give a try.
Have a great day,
TIC

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