V4 - Serial flash communication issue
Due to the mux (SN74LVC1G97DBVR) and depending on the clock
communication with the M25P32 flash memory might not work as expected.
The mux adds a delay to the clock signal, while the data line from the memory doesn't have a mux.
As a result the data appear to change a the rising edge instead of the falling edge of the clock.
See attached presentation extract.
In addition, the data line is floating when the chip is not selected.
Therefore, adding a pull-up/down should be considered.
This issue has been reported by Magnus Vik Sundal and Heiko Damerau.