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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks David for the very quick feedback. For others that might see a similar symptom of MISO not toggling, here is what I did wrong. This part is a QSPI.
It can work in a number of modes, for single bit SPI, up through four bit SPI. On the board, there were some missing pullup resistors. MISO, #HOLD, and #WP did not have pullups. When I added 4.7K ohm pullups to those three pins, the MISO started toggling
and flashrom reported that “This flash part has status NOT WORKING for operations: PROBE READ ERASE WRITE “ This is to be expected, as the N25Q256 is not supported.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">On this Micron part, the #HOLD, and #WIP pins are dual function. In four bit mode, they are data bits. Therefore, the need for pullups is not obvious.
However, until I added them, the part was dead as a mackerel. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I could not find the Chromium branch, so I could not try that version. I did try the latest release candidate, but it operated the same. However, we don’t
really need that large a PROM, so we have N25Q128 chips on order for delivery tomorrow. I believe that one is supported, so we should be able to program after swapping the chip. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> David Hendricks [mailto:dhendrix@google.com]
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<b>Sent:</b> Wednesday, March 30, 2016 06:11 PM<br>
<b>To:</b> Steve Miller<br>
<b>Cc:</b> flashrom@flashrom.org<br>
<b>Subject:</b> Re: [flashrom] Programming N25Q256 ?<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Wed, Mar 30, 2016 at 3:14 PM, Steve Miller <<a href="mailto:stevem@tanisys.com" target="_blank">stevem@tanisys.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Stupid Noob Questions:<o:p></o:p></p>
<p>1.<span style="font-size:7.0pt"> </span> Is the static level on MISO to be expected? Or should it at least toggle?<o:p></o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">That said, the N25Q256 is not currently added in upstream flashrom. There is limited support in the Chromium branch, though.<o:p></o:p></p>
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<p>2.<span style="font-size:7.0pt"> </span> Is there any hope with this device? Can I perhaps force it to think the chip is smaller?<o:p></o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">*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...<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">David Hendricks (dhendrix)<br>
Systems Software Engineer, Google Inc.<o:p></o:p></p>
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