Winbond W25M512JVFIQ serial Flash
The Winbond W25M512JVFIQ is a stacked SPI Flash, meaning it consists of two seperate 256 MBit SPI Flashes. Both SPI Flashes share the same Pins and by default always Die #0 is selected for access. To select the second SPI Flash die #1 it is necessary to send special command to the SPI Flash, after sending the command you access die #1 similar to accessing die #0 before.
Selecting second Flash die of Winbond W25M512JVFIQ serial flash
The following initsteps show how to reconfigure the serial flash to select the second die of the stacked SPI Flash