Bill Greiman

There is nothing you can do to make an SD go not busy. Once the SD needs to program flash it will go busy. When it finishes, it will go...

Have you tried other SD cards? Consumer grade cards have limited flash endurance. TLC (Triple-Level Cell) flash, commonly found in consumer-grade cards, typically has around 500 write cycles per physical...

> how much data i can write once before closing a file With exFAT, which is the file system for SD cards larger than 32GB, you can log the entire...

> can i use both O_TRUNC and O_SYNC I removed use of O_SYNC long ago. It does nothing. Also it is not recommended in Linux. It is still defined in...

Could you try [SdFat-beta](https://github.com/greiman/SdFat-beta). It has support for RP2350B. Edit: I am still making major changes to SdFat-beta so it would be helpful if you tried the attached version. Unzip...

I just tried another SD with the Metro RP2350 board. Looks like the problem was the SD I was using. Here is the bench example at 200 MHz: > Type...

> Curiously, changing the clock divisor didn't seem to have any impact to the benchmark results. Something is wrong, your speed is nowhere near what I would expect for PIO...

It may be your SD socket/module or wiring. SdFat uses a much higher default SPI clock than SD.h. SD.h is based on an old version of SdFat that I wrote...

> What is a good value for SPI_CLOCK? I don't know where this is defined, as I had to add my own #define SPI_CLOCK to get it to compile. See...

Looks like a card not certificated by the SD Association. Reading the card size failed. Since the SdInfo example read the card size I suspect your setup/card has a problem...