Two SDIOs on RP2040

[Stass48]

Hello! I’m really sorry for the silly question — maybe someone has already asked this (but I couldn’t find it).
1. Could you please tell me if it’s possible to use two SD cards on a single RP2040 (for data copying and other tasks)?
2. Will other PIO-based interfaces, such as I2S, still work properly in this setup?
3. Will there still be any remaining PIO resources available on the controller with such a configuration?

I apologize if my questions seem too basic. I truly appreciate your help and willingness to discuss these topics. I remember our conversation a year ago — you helped me a lot back then. Thank you so much for everything!

[greiman]

1. Could you please tell me if it’s possible to use two SD cards on a single RP2040 (for data copying and other tasks)?

You can use many SPI cards but only one SDIO card. There is not sufficient memory in a PIO block to add support for multiple cards on one PIO controller.

2. Will other PIO-based interfaces, such as I2S, still work properly in this setup?
3. Will there still be any remaining PIO resources available on the controller with such a configuration?

PIO SDIO uses one PIO block. RP2040 has two blocks, RP2350 has three blocks. SdFat checks for free PIO resources and reserves them. Some PIO interfaces libraries do not check/reserve PIO resources and will not work reliably.

[Stass48]

Thank you for your answer 🙏

You can use many SPI cards but only one SDIO card. There is not sufficient memory in a PIO block to add support for multiple cards on one PIO controller.

Does this apply only to the RP2040? Or does the RP2350 have the same issue with a lack of PIO memory?

[greiman]

Does this apply only to the RP2040? Or does the RP2350 have the same issue with a lack of PIO memory?

PIO blocks in the RP2350 have the same amount of memory as the RP2040.

I suspect there could be problems implementing more SDIO features in PIO. I was only able to implement the most basic SDIO features with PIO.

[Stass48]

Thank you, Bill. You're amazing!