Bill Greiman

Thanks for testing. All M0 Arduino boards I have put on a logic analyzer run slower than a Uno at 8 MHz. Uno at 8MHz: ``` write speed and latency...

Great improvement. I think I see the problem with the STM32 SPI wrapper. The SPI controller has a buffer register and shift register for both RX and TX. The loop...

I rearranged the loop in the ST wrapper and made slightly better use of the SPI controller and got a substantial improvement in bench without danger of receive overrun. Here...

I have posted a [custom SPI driver](https://github.com/greiman/SdFat-beta/blob/master/src/SpiDriver/SdSpiSTM32Core.cpp) on SdFat-beta so the default speeds are much faster for higher end chips like STM32F4. It use transfer(tx_buf, rx_buf, count) for send but...

> This probably wouldn't work for receiving, because SD-cards are bitchy if they don't receive 0xFF when being read out and it really depends on the SPI implementation what is...

Software SPI won't work well with the LowLatencyLogger since Software SPI is very slow. > I got a lot of errors What are the errors?

You are on your own. I don't have time to help with mods.

Glad to see you found a fix. I don't have a working ESP32 so I would have never been able to guess the speed problem. I am puzzled why these...

Use [SdFat-beta](https://github.com/greiman/SdFat-beta) on Teensy 4.

> Pretty sure this is a scoping issue but how can I avoid this? I have no idea.