This is a quick way to add extensions inside the chassis. With a 1x4 usb 2.0 hub, we could host a sound card, a usb-pcmcia adapter, parallel/serial port, etc. etc.
The hub is small:
To connect the hub, one USB port on the EXT board has to be removed:
Note: The pads for the original usb port are not spaced evenly 2.54mm, so I have to break the connector pins into individual ‘needles’ and adjust the position one by one, to fit the 2.54mm cutehub.
I don’t want to leave a hole on the outside, and I want to control the power of individual devices, so I added a few switches where the original USB port was:
The switches turn out to be very useful: Teensy draws about 500mA(!) so when not used, better turn it off.
With switches off:
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 004: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 001 Device 009: ID 1eaf:0024 Leaflabs DevTerm
Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
axp20x_battery-0: 3.941V, 1.002A
With Teensy switch on:
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 011: ID 16c0:048a Van Ooijen Technische Informatica M8
Bus 001 Device 004: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
axp20x_battery-0:3.906v, 1.325A
wrt. schematic: sorry I mostly improvised the connections
anyway the wiring is simple, and the most challenging part is to remove the original usb port… I ended up cutting the “landing pads” which are too cumbersome to unsolder.
After removing the usb port, 4 pads are exposed: 5V, DM, DP, GND.
The EXT board marks 5V as 1 and GND as 4, straightforward.
For power control: connect a switch between hub downlink 5v and device 5v. When 5v is floating, by usb standard the device won’t connect (it becomes unpowered in our case)
Oh, thank you for that pointer - the TinkerBOY looks like an option, albeit a lot more expensive than I was seeing the other board, similar footprint at least. Interesting. Thanks!
I remember back in the day we’d desolder one USB port from an Asus eee, flip it upside down and glue it to the PCB, then wire the PCB pins to a usb hub and then one of the hub ports back to the upside down USB socket so we could still use it, but have some internal USB ports. This looks like a better version of that.
I know the intention was for folks to make their own expansion boards for the devterm, hopefully someone comes along with one that just has an internal usb socket or two so we can do things like put 4g dongles and SDRs inside easily
I’ve been wondering why 1 USB port wasn’t exposed somewhere internally. Not putting an internal USB port on that expansion board was a missed opportunity for the design.
I’ve had a small USB hub (not that small) and thinking about how to get something similar going. Thanks for the post.
I did something similar with my RTL-SDR addition (there’s a thread on it here somewhere), this looks like a much cleaner way to accomplish this; I get the feeling I’ll be ordering one of these to try. I went full caveman and removed the plastic shell off a cheap unpowered hub I had
)
cunning!