RT1176 - flexSPI DQS connection for max R/W speed

[nickwallis]

Hi,

We are using RT1176 with external octal (hyper) flash, the same as the EVK board schematics.

There is a note in the schematics (and in the reference manual) that says the DQS pin (GPIO_SD_B2_05 on ball E14) must be left floating to achieve maximum flexSPI RW speed.

My question - this signal (FLEXSPI1_A_DQS) is also available through the pinmuxing on GPIO_EMC_B2_18 (ball N3) - if we use this pin for the DQS signal and leave pin GPIO_SD_B2_05 on ball E14 floating, will we be able to achieve the maximum flexSPI RW performance.

The same question applies to the SEMC_DQS signal on GPIO_EMC_B1_39 (ball J2).

thanks

-Nick

[yosri_c]

hello , i have an issue with our custom board using the RT1176 we are interfacing with a flash NOR IS25LP128 , we could only reach 60Mhz freq , we really need to raise at least to 100Mhz , but we couldnt get there 

is there anything we might have missed or any change we need to do 

[jeremyzhou]

Hi,
Thank you for your interest in NXP Semiconductor products and for the opportunity to serve you.
1) My question - this signal (FLEXSPI1_A_DQS) is also available through the pinmuxing on GPIO_EMC_B2_18 (ball N3) - if we use this pin for the DQS signal and leave pin GPIO_SD_B2_05 on ball E14 floating, will we be able to achieve the maximum flexSPI RW performance.
-- For the Octal Flash, it has the MQS pin, so it needs to connect FLEXSPI1_A_DQS to achieve maximum performance.
2) Regarding SEMC_DQS, it is recommended to be floating to achieve max speed.
Have a great day,
TIC

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[nickwallis]

thanks @jeremyzhou but that didn't answer my question

Yes, we need FLEXSPI1_A_DQS signal to connect to octal flash DQS pin.

My question - does it make any difference to performance if we use RT1176 pin GPIO_SD_B2_05 for this, or if we use RT1176 pin GPIO_EMC_B2_18?

The EVK schematics say if you want maximum performance, then do not use pin GPIO_SD_B2_05.

But what is the performance if we use pin GPIO_EMC_B2_18?

-Nick

[jeremyzhou]

Hi,
Thanks for your reply.
1) Does it make any difference to performance if we use RT1176 pin GPIO_SD_B2_05 for this, or if we use RT1176 pin GPIO_EMC_B2_18?
-- It can't use the GPIO_EMC_B2_18 instead of the GPIO_SD_B2_05 as the FLEXSPI1_A_DQS to connect the octal flash.
2) But what is the performance if we use pin GPIO_EMC_B2_18?
-- Below note is used to remind the customers that use the QSPI as the boot device, however, you use the octal flash and please just ignore it.

Have a great day,
TIC

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[nickwallis]

thanks @jeremyzhou 

1. Why? I think reading the RM it can be GPIO_EMC_B2_18?

2. OK thanks, I didn't realise this note does not apply to octal flash.

-Nick

[jeremyzhou]

Hi @nickwallis ,
Thanks for your reply.
Actually, FlexSPI1 2nd DQS is not actually supported in BootROM, Doc team will remove this pin from bootROM pinmux table in the next version of RM.
Hope this is clear.
Have a great day,
TIC

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