SdFat with SDIO support. #73
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Great! Good news for the Arduino / PlatformIO users. I've retrofitted Arduino compatibility to this library, but prior to that I had never used Arduino, so it was an afterthought. |
Arduino is not for serious projects. I have tried to isolate the core of SdFat so I can use it on systems like ChibiOS. I see you also have used STM32 chips also. I had hope for Arduino in 2008 when I first tried it but it never evolved as I expected. The Arduino guys make lots of money catering to to their huge crowd so it makes good business sense. |
I noticed the
This library actually started as a port from a project on Cypress PSoC, followed by a port from FreeRTOS+FAT to FatFs, when the Pico first came out. Then the PSoC project migrated to STM32. I have learned a lot and found a lot of bugs by open sourcing the code and maintaining it multiple platforms. When I started the PSoC project, years ago, PSoC Creator made it really difficult to use C++, so even though I previously had used C++ daily for 12 years I did everything in straight C. Also, that seemed appropriate for an embedded library; consistent with the Pico SDK. But, SdFat shows me what I was missing. Meanwhile, STM32CubeIDE makes it less painful to use C++, and some is creeping back into my larger applications. |
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I've been thinking that 1-bit SDIO could be a nice alternative for highly pin-constrained projects, like in Hardware design with RP2040. I'll have to study your PioSdioCard.pio. There is pico_sd_card, "but the code is very much a prototype". You'd need no SPI and only three pins: SCK, CMD, and D0, and the pin assignments would be very flexible. I guess performance would be similar to SPI. |
I did a PIO SPI that I could clock at high MHz and got the same rates as 1-bit SDIO - it is really simple. I will look for the code. |
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Here is an "as is" copy of my PIO SPI tests for SdFat for RP2040 from about a year ago. Very rough - in development. The zip has the library and a version of bench setup for a Adafruit Metro 2040. I ran it today with this result:
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This is not an issue, Just to let you know I finally posted a beta version of SdFat with RP2040/RP2350 support here.
My main goal was Arduino users with small transfers. Here are some results from the bench example.
Pico 2 small 64 byte transfers 150 MHz:
Here is the result with 512 byte transfers that avoid cache copies:
Pico 2 512 byte transfers at 150 MHz
Finally large transfers and overclocking.
Pico 2 large transfers at 250 MHz
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