IMXT 1170 FLEXSPI LUT table issue and know how

[Desmond_lim]

Let’s start from the NOR Flash IC spec, which is similar to the SDK (ISSI). Let’s pick one command (0x9F). This command will return 3 bytes (MF, ID2, ID1). Please refer to the diagrams below.

1. As you can see from the second diagram (MF = 0x9F; ID1 = 0x18; ID2 = 0x60)

1. I was using the LUT table from the SDK. Please refer to the diagram below too. I didn’t change this because it seemed working but when I tried to get the last two bytes (ID1 and ID2), it is giving me some troubles.

1. Using the SDK code, I managed to read MF = 0x9D. (Same as the ISSI spec), then when I read the other two bytes, I got (0x00, 0x00) or (0x00, 0x61).

I don’t know why calling the same command will give me different outputs at different time. Another problem is that both outputs are completely wrong!

I found that the SDK is also _NOT_ outputting those two bytes for some reasons.

1. I tried to change the LUT command.

1. I changed the (….., 0x9F, .., kFLEXSPI_1PAD, 0x04) to the (….., 0x9F, .., kFLEXSPI_2PAD, 0x04) è MF = d9, ID1 and ID2 same (wrong)
2. I changed the (….., 0x9F, .., kFLEXSPI_1PAD, 0x04) to the (….., 0x9F, .., kFLEXSPI_4PAD, 0x04) è MF = fd, ID1 and ID2 same (wrong)
3. I changed the (….., 0x9F, .., kFLEXSPI_1PAD, 0x04) to the (….., 0x9F, .., kFLEXSPI_1PAD, 0x08) è MF = 9d, ID1 and ID2 same (wrong)
4. Running out of parameters to change. Try to study the other examples but I don’t know whether if the output is correct or not. Only MF and ID1/2 can be verified with the ISSI IC spec.
5. Read the document how to change the LUT, getting more confused. Rather sad because there is completely no documentation to this powerful table.
6. GIVE UP in experimenting!!!!
7. LAST RESORTS:  Ask NXP for help on a few things.
1. How to make this 0x9F work after that?
2. LUT know-how (document, tutorial or anything available) and how I can change it in case we change the NOR Flash IC to some other brand.

That’s all from me.

This is urgent to us and it could be at your fingertips. Please help. Thank you.

[Desmond_lim]

I found what my problem already and it is basically the mistake in the other part of the code. I managed to fix that part and it works. The problem of following the SDK code blindly.

Anyway, the solution is not in the LUT but in another part of the code.

Having said that I still need to understand this LUT table and how to change it because

1. Fully understanding of the LUT will prevent us changing the wrong thing in the future.
2. Obviously, I cannot comprehend fully the LUT and hence this investigation happens.
3. Need some documentation on the LUT or some tutorial in case I need to change the table for new NOR flash IC with different brand.

Please help me to understand this LUT. I think it is a very powerful table and it is a shame that I still don’t know how to use it well.

[jingpan]

Hi @Desmond_lim ,

The most detailed information about LUT and FlexSPI is reference manual. There are some AN you can refer to, include AN12239, AN12183, AN12108.

If you can read Chinese or use interpretation software, you can refer to 

https://www.cnblogs.com/henjay724/p/14839206.html

https://www.cnblogs.com/henjay724/p/16702648.html

https://www.cnblogs.com/henjay724/p/14723615.html

Regards,

Jing