NAND flash hangs

Please help...

I'm trying to access a Samsung K9K4G08U0M NAND flash device with an Altera Cyclone II.

The NAND flash requires some setup signals do to a read from flash, ie. CLE, nCE, nWE, ALE, nRE, and IO. After I have setup these signals, the device's R/nB signal goes low, as expected, but it never goes high again!!! It just stays in the Busy state indefinitely!

The R/nB signal should stay low for a maximum of 25us for a read according to the data sheet.

Even when I execute the Reset command to the flash, the flash hangs in the Busy state.

I have already checked the hardware for shorts, the power rails for noise, and I have even replaced the NAND flash chip. I have checked the timing requirements for the setup signals and I have tried slowing everything down to half speed.

I think my setup signals are correct, because the flash responds to them, but I may be wrong.

Does anyone have any experience with this problem or advice for me? It would be greatly appreciated. Thanx Eric

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Loading thread data ... schrieb:


I just connected NAND flash to Xilinx OPB_EMC (sram-flash IP core) and I had no issues.

CLE to A0 ALE to A1 nCE GND

and it seems to work. you must keep nCE low during all transfer except for special "CE DONT CARE" option NANDs

hum your chip seems to be "CE DONT CARE" so you can connect nCE to the CS of the controller as well

Antti PS the best testing is - connect it to GPIO and test, then later connect to the system memory controller

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Are you sure there is a pull-up on the R/nB signal? It's an open drain signal.


Reply to
Marc Battyani

Yep, needs a pull-up.


Reply to
Andy Peters


It needs the pull up resistor! I can't believe that I missed it!

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