nRF52840 Preview DK v0.9.x

External memory

The nRF52840 Preview DK board has a 64-Mb external flash memory. The memory is a multi-I/O memory supporting both regular SPI and Quad SPI.

The memory is connected to the chip using the following GPIOs:

Table 1. Flash memory GPIO usage and connecting solder bridges
GPIO Flash memory pin Solder bridge for memory use (default: shorted) Solder bridge for GPIO use (default: open)
P0.17 CS SB15 SB25
P0.19 SCLK SB11 SB21
P0.20 SIO_0/SI SB12 SB22
P0.21 SIO_1/SO SB13 SB23
P0.22 SIO_2/WP SB14 SB24
P023 SIO_3/HOLD SB10 SB20
To use the GPIOs for a purpose other than the onboard external memory and have them available on the P24 connector, six solder bridges (SB10SB15) must be cut and six solder bridges (SB20SB25) must be shorted. See Figure 1 for details.
Important: If debugging the QSPI communication is needed, the SB20SB25 can be shorted without cutting SB10SB15, but the pins should not be driven externally.
Figure 1. Configuring GPIOs for external memory

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