nRF52840 DK v1.0.0

External memory

The nRF52840 Development Kit (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 SB13 SB23
P0.19 SCLK SB11 SB21
P0.20 SIO_0/SI SB12 SB22
P0.21 SIO_1/SO SB14 SB24
P0.22 SIO_2/WP SB15 SB25
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 the following figure for details.
Note: 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
PCA10056 board: Configuring GPIOs for external memory

By default, the power supply of the external memory is coming from the VDD domain and it is controlled by the nRF only switch (SW6). In the nRF only mode, there are two optional power sources for keeping the external memory powered, VDD and VDD_nRF. If VDD_nRF is selected, the power consumption of the external memory will be added to the nRF52840 current measured on P22 or P23. See the following table for configuration:

Table 2. Flash memory power source configuration
Power source Solder bridge Default state
VDD_PER SB16 Shorted
VDD SB17 Open
VDD_nRF SB18 Open