Hi,
Once we drive the GPIO4_IO16 (N19) high or low or as input (high or low), after that SPI NOR Flash does not communicate. We have to reset the board to get the NOR Flash working again.
For NOR flash, we have used following pins:
ESCPI3_SCLK (P24)
ESCPI3_SS0 (P21)
ESCPI3_MISO (P23)
ESCPI3_MOSI (P22)
During this test we have not observed SPI clock and data. In PCB traces from P21 to P24 and N19 are in opposite direction, so there is no doubt of cross-talking.
With regards
Lalit
