I am currently in the scoping phase for a product that saves high frequency data to an external SPI flash chip and dumps that data over Wi-Fi once it returns to an area covered by an Access Point. For power efficiency reasons, it is desirable to complete this dump process as quickly as possible so we can disconnect from the network ASAP. We wish to use a nRF54L15 paired with a nRF7002 to achieve this. Each dump is likely to contain > 4MB of data, making internal RAM caching impossible.
Based on the WiFi throughput docs, the maximum throughput that can be achieved is approximately 16 Mbps.
Sending 16 Mbps of data over UDP implies reading at least 16 Mbps of data from the flash chip.
This eliminates the option of using one of the 8 MHz SPI buses for either the Wi-Fi or the flash chip.
Trying to connect both devices using standard SPI @ 32MHz would require 100% bus utilisation, which is not realistic (even ignoring overheads).
Unfortunately based on my reading of the data sheet, the QSPI and SPI both use the same pins for 32MHz operation, so we cannot operate both at the same time on independent pins.
Is it possible to run both external flash and nRF7002 together on the shared QSPI bus (which would provide 128 Mbps of throughput)?
Or to run the QSPI and SPI buses in a time-multiplexed fashion on the same pins (which would provide ~96 Mbps assuming a 50/50 split)?
Alternatively, is there some other setup that I have missed for this particular use case which would enable maximum Wi-Fi throughput?