I’m working on a design of a carrier board for the Jetson Nano module which needs to have microSD card socket.
Jetson Nano data sheet in the section 4.5 SD /SDIO has a note that states: ‘SD Card functionality is not supported on this interface as it has a fixed 1.8V supply.‘
From the Table 16 SD/SDIO Pin Descriptions in the data sheet it’s clear that this interface pins are of CMOS – 1.8V [CZ] type.
Yet, the NVIDIA Jetson Nano Product Design Guide in section 7.0 SD CARD /SDIO on Figure 20: SD Card Connection Example shows a SD card implementation using 3.3V supply voltage.
Hence, my question: is the Jetson Nano module SDMMC interface 3.3V tolerant? If, yes what the note in the data sheet supposed to mean? If no, how the implementation suggested in the design guide could work if most SD cards would use (at least initially) 3.3V signalling voltage.
What is the revision of the Pinmux that show SDMMC3 (3.3V Capable). I have revision 1.01 does not show. Also, what is the grey field indicate in the pinmux file. I checked the “3.3V Tolerance Enable” column for the eMMC pins, they are grayed out. Thanks
‘SDMMC3 (3.3V Capable)’ is the name of the SDMMC interface sections in the Jetson Nano Pinmux 1.0 and more recent 1.01. Both versions have the ‘3.3V Tolerance Enable’ column for those pins grayed out. That could mean the 3.3V tolerance is not user configurable (i.e. can’t be disabled), but it would be better for NVIDIA to explain this.
Also, the JetsonNano_DataSheet_DS09366001v0.8.pdf still says on page 30 ‘NOTE: SD Card functionality is not supported on this interface as it has a fixed 1.8V supply.’
Although Table 15 below in the column ‘Supported Voltages (V)’ lists 1.8/3.3.