One of our boards has a problem while reading the device id of S25FL064L. Design is consist of the multiplexer, ethernet controller, nor flash, and spi header. We can select either an ethernet controller or spi header. When I selected to spi header, nor flash does not respond to the manufacturer id etc. I can read only 00 from spi emulator.
When I selected to ethernet controller, the MOSI pin seems weird. You may see that the signal level is about 1.6V. Flash also drives the MOSI pin. I think that nor flash was wrongly configured. ( I do not know how it is) It may be in QSPI flash mode.
Is there any way to exit from this mode using normal spi reading or writing?
1) Can you please share the waveform of the command sent by the controller to the Flash?
2) After resetting the Flash, does it start again QPI mode?
Also, Can you please let us know if in any operation the QPI_NV bit of the Configuration Register 2 non volatile is changed? If so you need to use a QPI communication to reset the bit to make the SPI protocol default in the Flash.
MUX selection is through to Header.
1) I sent the 0x9F command to read manufacturer id. There is no information from the flash device. (spi_1_000.png)
2) Yes, I try to tie the 7th pin of Flash to the ground. It is still not responding. (spi_1_000.png)
MUX Selection is through to Ethernet PHY. You may see that it tries to read something from Flash. The level of MOSI is weird. (spi_1_008.png)
When I tried to reset the Flash, MOSI changed. (spi_1_009.png)
I sent the different commands such as 0x05, 0x07, 0x35, 0x15, 0x33 from spi emulator. None of them did work. MISO is still ground level.
EDIT: I could not add my oscilloscope images. Can you share your email address, I can share it with you from there.
Can you please let us know the reason for you thinking that Flash went inside the QPI mode? Was there any part of your application that switched the flash to QPI mode?
Also, as you mentioned that only one board failed, Can you please try to use another Flash chip to check if the part under question is not a good device?
Can you please let us know out of how many boards did this one board failed?