Which type of flash can be connected to EMI

henk · ‎2005-07-27

Posted on July 27, 2005 at 14:12

henk · ‎2005-07-10

Posted on July 11, 2005 at 08:00

I am designing a board using the STR710FZ2 and want to use a flash memory connected to the EMI. Now there are several types of flash available. Do I have to use NOR flash or can I also use NAND flash on the EMI? Which types are used on the 'official' evalution boards?

Thanks.

henk · ‎2005-07-12

Posted on July 12, 2005 at 11:04

Thanks for your answer. It is too bad that the search function does not work properly. After I had gone manually through all pages, I found that this item had brought up before in May 2004. There reference was made to an application with the EMI of an ST9 which is using NAND flash. I have not found it yet on the site (again a properly working search function would help).

I still doubt though that NAND flash can be used since NAND flash uses a multiplexed (combined) data and address bus and I see nothing in the reference manual about this. The datasheet that you included is of a conventionel NOR flash with separate data and address buses just like also RAM and ROM memories use.

Thanks and regards

alok2 · ‎2005-07-12

Posted on July 13, 2005 at 02:36

Dear Revox,

I am not an expert of STR7x but in general, Flash interface to micro depends on your application. If you want to store lot of information in NAND flash, then this management has to be done by you in the firmware. If you want to use NAND for boot up, even this is possible. (see NAND flash with auto-page0 load options).

NAND flash is IO device, so address+data management is done on same data-bus using different control signal like ALE, CLE etc..This is very well achieved by EMI and these control signals can be connected to IOs. EVen EMI signals can be used and read/write can be done choosing specific address which will toggle the ALE,CLE.

As per my understanding from different forums, the refernces to ST92163 have been removed from internet because the product is no more promoted by ST. The ST9-NAND flash interface was done for mass-storage application. you can check with your ST marketing interface.

bye

Alok

henk · ‎2005-07-14

Posted on July 14, 2005 at 13:56

Dear Alok,

Thanks for your answer. I know that you can consider a NAND flash as an I/O device and that besides the multiplexed data/address bus there are some control signals like CLE and ALE. If however you need to control this via software, this is not an easy task to perform since the timing requirements are quite severe. That is why in memory cards for example there is a piece of hardware that interfaces between the NAND flash and the microcontroller. The external memory interface in the STR7 can be considered to be such a piece of hardware, however, I can only find the in manuals that it is usable with SRAM, Flash (NOR flash) and ROM. These pins are multiplexed with general purpose I/O's and of course, if you choose to not use the EMI but just the GPIO's and you connect NAND flash to it, then probably after a lot of hard work it is possible to interface with it. This is my understanding, correct me if I am wrong. If however I use SRAM or NOR flash, I can use the EMI and 'automatically' all the timings etc are correct if I choose the right memory devices.

It would be interesting though to find more detailed information about the ST92163 application that you mentioned before.

By the way, do you or someone else, happen to know the type number of the SRAM devices used on the STR710 Evalution board that ST supplies?

Regards,

Revox

alok2 · ‎2005-07-14

Posted on July 15, 2005 at 02:59

Hi Revox,

i dont believe that there are no IOs available for ALE, CLE in your design. For transfers on NAND, in terms of toggling the IOs ALE is only required to be put high when Address are out. So, 4/5 bytes that's it. for CLE 2-3 bytes. So IOs can be used.

Timing constrains are on minimum side, The NAND flash is quite fast there are hardly any issues when using EMI.

If you want to use EMI signals for ALE, CLE the best option is to define particular addresses. For example if you choose 0x8000, 0x4000 address from EMI, it will cause A15, A14 to be high respectively when data is output on the address 0x8000 & 0x4000. Just connect A15 to ALE, A14 to CLE and whenever you need to write command write on 0x4000. WHen you need to write Adrress write on 0x8000. FOr normal data read/write write on any other address less than 0x4000. This will cause the appropriate signals to be high when required. I did the same on ST9 for different interfacing !!

henk · ‎2005-07-27

Posted on July 27, 2005 at 14:12

Thanks for the further explanations. Clear and very useful.

Thanks again.

Revox