Waveshare ESP32-S3-Touch-LCD-3.5: LCD SPI clock 80 MHz - #303
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ThomasFarstrike merged 1 commit intoSep 28, 2026
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Measured on hardware: a full 480x320 RGB565 frame pushed straight through the bus takes 74.6 ms at 40 MHz (4.8 MB/s) and 41.4 ms at 80 MHz, with a clean panel by eye. The ESP32-S3 SPI master divides 80 MHz by an integer, so 60 MHz silently rounds down to 40; 80 is the only step up. This raises the full-screen refresh ceiling from 13 to 24 fps. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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Sweet! I can't wait to try this out on other boards as well! |
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Change
SPI_FREQfor the Waveshare ESP32-S3-Touch-LCD-3.5 board file goes from 40 to 80 MHz.Measurements (on the board)
Pushing the driver's own 30 KB DMA strips straight through
lcd_buswith LVGL paused (so no rendering cost, no queueing):Panel output was inspected by eye at 80 MHz across several boots: no noise, tearing or shifted rows. The LCD pins (SCLK 5, MOSI 1, MISO 2) go through the GPIO matrix and 80 MHz still worked.
Note for anyone tempted by a middle value: the ESP32-S3 SPI master divides 80 MHz by an integer, so a 60 MHz request silently becomes 40 MHz (measured identical to 40). The only step up from 40 is 80.
Caveat
The ST7796's datasheet write-clock limit is 62.5 MHz, so this runs the panel above spec; it has been stable on the one board tested here. If a unit shows artefacts, the fallback is the previous value.
🤖 Generated with Claude Code
With thanks to the scientists and engineers who did the hard, unglamorous work that got us here.