nRF54L15 Application: Using SPI Flash (4-wire) instead of QSPI for External Storage

[Anthony Yuan]

Hi Nordic Support Team,

I am working on a Matter application using the nRF54L15, and I have a few questions regarding the external flash configuration.

I noticed that unlike the nRF52840 examples, the nRF54L15 sample DTS (e.g., in the Matter accessory examples) uses spi00 instead of qspi for the external flash interface.

But the DK connected 6 wires to flash (For sQSPI? But the Matter sample seems not using it, am I correct?)

I am considering using a standard SPI Flash (4-wire) connected to the nRF54L15 instead of a full QSPI setup. Before I finalize the hardware design, I would like to clarify:

1. Compatibility: Is it fully supported to run Matter (including OTA/FOTA) using a 4-wire SPI flash interface on the nRF54L15?

2. Performance Impact: What are the practical implications of using SPI vs. QSPI? Specifically, how much will this impact the FOTA (Firmware Over-the-Air) speed or the time required for image verification and swapping?

Thank you for your guidance!

Yuan Bo

[Einar Thorsrud]

Hi,

Compatibility: Is it fully supported to run Matter (including OTA/FOTA) using a 4-wire SPI flash interface on the nRF54L15?

Yes. External SPI flash is supported.

Performance Impact: What are the practical implications of using SPI vs. QSPI? Specifically, how much will this impact the FOTA (Firmware Over-the-Air) speed or the time required for image verification and swapping?

For the same SPI clock speed, QSPI will be 4 times faster than SPI. This will impact the performance during verification and swapping. During transport over 802.15.4/Thread I do not expect you will see a noticeable difference, as the network will be the limiting factor.

PS: The nRF54L15 implements a Software based QSPI peripheral that runs on the VPR CPU. See sQSPI and the overlay file for SQSPI in the spi_flash sample.