I observed the waveforms of the external Flash when runCommand() is issued: In the case of the QSPI connection, “0x05” is added and the status register is read, as in “0x05”+“0xB9” and “0x05”+“0xAB”. In the case of SPI connection, however, “0x05” is not added and only “0xB9” and “0xAB” are observed.
In both cases, the enter or release command will cause a large current to flow through the external Flash. I have no idea why the behavior is different between onboard Flash and external Flash.
Also, I am wondering if it is possible to use QSPI connection for the external Flash since the onboard Flash is already connected to QSPI.