Accessing SD card data Teensy 4.1 by alternative means

N

nachoman

Member
Hi everyone,

I am hoping to find out if it is possible, can the SD card be written/read from the Teensy 4.1 without using the USB port. Previously I have been using MTP and had a USB plugged in, but I want access to that USB seperate and to be able to access just the SD card data from another USB or similar connection. I have looked over the forum and seems that people have had no luck - but that was only by using the USB pads underneath from what I could understand.

Has someone managed to use the USB pads to access the SD directly? Or could I use an SPI chip to interface with the SD card externally to read/write? Any suggestions would be great!

Thank you.
 
To answer on a purely technical level, yes, the SD card is fully independent of USB. For example, if you run File > Examples > SD > Datalogger, and you delete the "wait for serial port to connect" part so it starts up without any USB cable connected, it can read the analog inputs and write to your SD card. Of course you have to arrange to power the board without USB, but hopefully you can see the SD card is able to work without USB. For that sort of use, you would just physically remove the card and read it with a computer to get the data. No USB at all.

But to answer from the point of view of an application to meet your needs, well, I just don't quite understand your question. It doesn't sound like you're building a datalogger, like that example. I don't understand why you're asking about the USB pads on the bottom side (which are the same signals as the USB connector) in relation to the SD card.

Maybe if you explain your project and give more context about what you're really trying to accomplish, better advice could be possible.
 
Hi so essentially wanted one USB port that is the native, so I can program from a device. Then I wanted the SD card to be accessable from a different USB port which I'd connect another device to. Is that possible?
 
It's possible only in theory, as in the hardware could do it. But today there isn't software published to do so. The available software for the 2nd USB port only supports host mode, where you would plug in a USB flash drive or hard drive. It does not support device mode on the 2nd port.
 
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