The "Chris Cunningham" YouTube video described an arrangement by which one could connect a datastick and an iphone and read the data from the stick without removing it -- I think. He didn't show the wiring, however, just mentioning a Nomad splitter. I'm not sure that one leg of a "Y" can read data from the other leg of the "Y". Can it? I'd like to know the cabling configuration. With 2 USB ports in my "3", wouldn't I just need a "Y" or hub that enabled one leg (the one with the geekgo adapter) to read from the datastick connected to the other leg? Is the "Y" needed, or do the two ports in the car accomplish the same thing?
Roger
Roger,
Cunningham is _not_ transferring data via cable connection.
The SD card reader he is using (I use a similar strategy) behaves as a typical “Mass Storage USB device” when connected to devices such as personal computers with its USB-A connector (the largest rectangular connector common to the first generations of USB ports on computers), and with a “TeslaCam” directory at the root level of the inserted SD card, serves as a suitable DashCam storage device for Teslas.
In order to read/write to an inserted SD card, the reader must be _removed_ from the Tesla (be SURE to stop TeslaCam by pressing on its icon until its red recording indicator turns off), and then connected to an Android device via USB On-The-Go (OTG) cable, or by plugging its Lightning connector into an iOS device (this requires running a free iOS app downloaded from the App Store).
The USB communication standard doesn’t allow multiple data devices to share the same electrical data connections concurrently. Inside those USB “hubs” which allow users to plug multiple printers/scanners/phones/etc., those multiple concurrent devices are independently moderated with their own controlling circuits, and are NOT sharing the same electrical connections. The somewhat unorthodox “USB splitter” cables we’re encountering now in the Tesla community reflect the unique use-case of: 1) needing additional USB ports for charging, but 2) not necessarily for data. These “Y cables” feed power to the appropriate pins of both of their female USB-A jacks, but only have data wiring to one of the jacks (again, because two USB data devices can’t coexist on the same physical wire). For us Tesla owners, this allows us to connect one USB data (and powered) device _and_ one USB-powered device to each of our two available USB data/power ports (the USB ports at the rear of the Model 3 console are power-only, with no data connection).
While USB hubs can provide charging power, most require an additional power source independent of the host computing device. This is why an AC power supply is often connected to hubs, and why the same kind of hubs wouldn’t be appropriate in our Teslas to solve our charge/data problems without some additional modifications (providing power to the hub from the car’s 12-volt power).
NOTE: While both jacks of these USB splitters can be used for power concurrently, a USB host circuit provides a fixed limit of current, (measured in amps or amperes). Most USB host devices (i.e., computers) will issue warning prompts if the current limit is exceeded. I don’t know how Teslas handle excessive current notifications.
Regards,
Ellsworth 2018 TM3 LR RWD