Richard Bamford

Yes i'm looking to do high speed transfers, so SDMMC might actually be slower?

> > > I forgot one other disadvantage. The SDMMC controller causes the SD to need to copy data from partial filled flash pages so there are occasional writes with...

Have you tried a device with built in SDMMC hardware? https://www.st.com/content/ccc/resource/training/technical/product_training/0d/2d/cc/55/55/a6/42/12/STM32L4_Peripheral_SDMMC.pdf/files/STM32L4_Peripheral_SDMMC.pdf/jcr:content/translations/en.STM32L4_Peripheral_SDMMC.pdf

> I suspect you could go directly in STM32Cube and make a faster SPI driver for SdFat. Here is an example, [UserSPIDriver.ino](https://github.com/greiman/SdFat/blob/master/examples/UserSPIDriver/UserSPIDriver.ino), that shows how. > > If you want...

Using normal .write() with the SDMMC interface, i can get speeds of 33192B/s, i am just integrating it with the buffers now to see what it is like

> > > I tried another idea for a better SPI driver. I was able to get 1946 KB/sec on a Nucleo F446RE. > > Here are the two files....

wow that is awesome results, i don't quite fully understand how to configure the 2 SPI ports but i will definitely look into it. i'll need to reconfigure the USART...

> All data rates are all for DEDICATED_SPI. > The second and third port on STM32F446RE run at 22.5 MHz max. I get 1206 KB/sec on those ports. > The...

Hmm, i'm using a 32,768 bytes FIFO buffer, 16,384 cache buffer for writing to the sd card. Samples are gathered at 16KHz and put into the fifo buffer, when there...

> > > I suspect the SDMMC controller/driver with STM32SD library will never work. > > Which STM32 chip are you using? What device are you collecting samples from? How...