RE: case about nRF54L15 QSPI

Marte Myrvold — Tue, 01 Sep 2026 08:01:37 GMT

Hi,

1. The nRF54L15 software QSPI can run up to 64 MHz. In 4-bit mode, that is roughly 256 Mbit/s raw, which means about 32 MB/s usable data rate before protocol overhead.

2. If the flash and display are on separate interfaces, then yes. If you are using the same QSPI bus for both at the same time, it cannot be done simultaneously, as one QSPI peripheral cannot serve two masters at once.

3. With a 240x320x16-bit screen, one frame is 240 x 320 x 2 bytes = 153,600 bytes. At 64 MHz, QSPI in 4-bit mode delivers about 32 MB/s raw throughput, which would give a theoretical max FPS of 32 MB/s / 0.1536 MB/frame ≈ 208 FPS. However, the actual FPS will be lower due to flash command overhead, DMA setup, display timing, and panel/controller limits. So 60 FPS is a more common practical target. Please also note that this assumes that the screen and flash are not on the same interface.

Best regards,
Marte