NetBurner Community Forum

We have a Nano 54415 on a board connected to a microSD card using four Data0-3 lines plus CMD and clock interface. This is Secure Digital Mode/SDC mode instead of MMC. The Nano Eval board has only a MMC mode using 1 Data line plus CClock and CMD lines, and the software user guide effs_fat262.pdf, Section 7 implies the system only supports SPI mode, even though the Netburner pin-out implies full 4 data line support.

Using the FileSysUtils, on boot up we get :

Mounting drive in USE_MMC mode.
-Drive mount to SD/MMC failed!
-ERROR; EFFS operation error code: F_ERR_TASKNOTFOUND

Scoping the lines, we find CMD, DAT2, DAT3 ares always high, only the CLK and DAT0 and DAT1 are actively pulsing when trying to mount the drive.

Can the Netburner library support the MicroSD card in full 4 bit SDC interface mode, or only the one DAT line, 1 Clock, 1 CMD line that the MMC mode uses? The Nano pin-out has the DAT0-3 pins that seem to support SDC mode, why does the library not support it?

The answer to your question is two-fold.

Yes, the hardware will support an SD driver that runs with the 4 separate data channels.

No, the software does not currently support that feature.

As of this writing, creating a driver for the SD Host Controller to run SD cards is on the future development list but is not actively in progress on our end. If you however wire the SD module in the same fashion as is on the NANO development carrier board (nburn/docs/Platform/Schematics/NANO-ADPT-100CR-SCH-R1p1.pdf for schematic), you will have an SPI based driver that does run. So short answer, if you need something that runs today, use the SPI driver and wire it as above. If you need SDHC performance and want to work on it yourself, the hardware is there, but we don't currently have the software to support it.

If you're trying to use the on-board SD card on the reverse side of the NANO module itself, I believe it's wired for the SDHC module and doesn't work yet. NXP/Freescale unfortunately swapped a couple of the pins so the card can't quite just be wired the same way for SPI and SDHC performance. The on-board card for the NANO was always meant to work with the SDHC once we had it working though.