On Wed, Mar 30, 2016 at 3:14 PM, Steve Miller <stevem@tanisys.com> wrote:

Hi,

I have the code built and running on a Raspberry PI. Unfortunately, the target part I am trying to program is a Micron N25Q256. I don’t see that part in the list. When I execute the program with –VV it seems to scan lots of devices. I see activity on CLK, CS, MOSI with an oscilloscope. But MISO remains logic low. When the program terminates, it just tells me No EEPROM/Flash device found.

Stupid Noob Questions:

1. Is the static level on MISO to be expected? Or should it at least toggle?

You should definitely see some activity on MISO. Flashrom sends identification instructions (RDID, REMS, etc) to the chip and the chip should respond with its JEDEC-assigned manufacturer ID and vendor-specific device info.

That said, the N25Q256 is not currently added in upstream flashrom. There is limited support in the Chromium branch, though.

2. Is there any hope with this device? Can I perhaps force it to think the chip is smaller?

Yep, that's what we currently do in the Chromium branch*. The chip uses 24-bit addresses unless either a bit in a nonvolatile config register is set or alternate instructions which accept 32-bit addresses are used.

*Full 4-byte address support should be ready soon, I just need to find a few spare cycles to finish up what I have written...

David Hendricks (dhendrix)
Systems Software Engineer, Google Inc.