Bill Greiman

I tried a slight optimization using the current SERCOM driver. I get this result: > FreeStack: 28008 > Type is FAT32 > Card size: 32.01 GB (GB = 1E9 bytes)...

Got a bit more with inline. > FreeStack: 28008 > Type is FAT32 > Card size: 32.01 GB (GB = 1E9 bytes) > > Manufacturer ID: 0X1B > OEM ID:...

I also tried similar optimizations. Next I looked at the datasheet for SAMD21 SPI. It has lots of buffering that is not used here. > The SPI uses the SERCOM...

I deleted all the failed or poor attempts to optimize` transfer(const void* txBuf, void* rxBuf, size_t count)`. Here is what I hope is the final attempt. Add the these lines...

I posted a Discussion on the Arduino site [here](https://github.com/arduino/ArduinoCore-API/discussions/189). I suspect I won't get any results. I looked at mods to the Arduino SAMD SPI driver and no recent pull...

I have not had anything accepted at Arduino or Adafruit about problems with SPI drivers for two years. There are lots of outstanding issues both places. So I have given...

I can't guess what is happening with so little information. The only issue reported with the Nano 33 BLE was slow performance [here](https://github.com/greiman/SdFat/issues/383).

The flash pages on an SD are huge and the buffering and access is designed to be a sequential stream if you seek to a previous sector, I must cancel...

The problem is internal to the SD. When you end a multi-byte write, the SD will program a flash page which contains many, 32 or more emulated 512 byte sectors....

I can't help with software SPI on ESP32. Perhaps someone has a working ESP32 software SPI package and you can use it as [UserSPI](https://github.com/greiman/SdFat/blob/master/examples/UserSPIDriver/UserSPIDriver.ino). There are too many boards for...