HHKB USB power rail mod?

[JunkFace]

I have a question for anyone who may know the answer: I remember hearing the usb on the HHKB2 was unpowered but it provides enough to power my ducky pocket with LED's and LCD powered on.  It won't however power my work mouse (which is a steelseries rival 300).  I'm working right now so I can't use a volt meter to test it but I could have sworn the HHKB had unpowered USB ports.  I don't think it would be impossible for the mouse to use more power than the 10key.

I'm wondering if my issue is a lack of power or it's the data.  The constant polling has to be fairly data-intensive.

You can get USB ports with one male connector that can power a number of devices which makes me think either some hardware or the board controller blocks power.  I've never taken a HHKB apart so I don't know but that's my guess.

If the HHKB's  USB's are  unpowered how tough of a mod would that be?  USB is already designed to supply power so it sounds like bridging the power rails would be fairly straight forward.  I mostly work on big old amplifiers so I have a decent amount of electrical engineering experience.  This sounds like a nifty little mod, I'd like to give it a shot if the consensus is this can be done without too much risk.

[Tactile]

You've seen unpowered USB hubs, which just plug into a USB port. And you've seen powered USB hubs which, in addition to connecting to a USB port, also have a connection for an external power supply - which is usually supplied with the hub. The HHKB USB ports are like the first kind. There is simply a limit to how much power can be pumped through that USB 2.0 cable between the HHKB (or an unpowered USB hub) and the computer.

[JunkFace]

So, in my case you think it's a power issue for the mouse?  The mouse will work with USB ports without external power. 

If the issue is the controller board blocking the power it shouldn't be **TOO terribly difficult to bypass the keyboard almost entirely and go straight off the incoming USB from the PC. 

Like I said, it's able to power a Ducky Pocket which you would think uses more power than a mouse.  I could see if I couldn't power them both at the same time but the HHKB never powers the mouse.  The mouse does work with normal USB ports so the HHKB must be limiting the amount of power makes it there in some capacity.  I think if I were to wire the HHKB up like a multi USB port it may provide enough power. 

[JunkFace]

Okay.  So I got home and busted out the mutlimeter.  I grabbed an old USB/USB B and stripped the end so I could easily get at the power and ground pins, then I used aligator clips to connect them.  Then I got annoyed with that and got proper aligator clips for the multimeter.  I measured the voltage and current from 4 sources: a regular motherboard USB 3.0 and 2.0, a usb hub with power cord, and the HHKB itself. Here are my findings:

Un-Powered USBs

This is a USB 2.0 coming off my motherboard. 

Reading:
5.1VDC .87A





Un-Powered USB 3.0

Reading:
5.1VDC .86A

This is a USB 3.0 coming off my motherboard.




Powered USB 

Reading:
5.17vDC .91A

This is powered USB 3.0 Hub, the 7 port version of the one you linked Tactile.  It has a dedicated wall jack and some kind of transformer and rectifying circuitry.  Reading is ~5.1v https://www.amazon.com/AmazonBasics-Port-2-5A-power-adapter/dp/B00E6GX4BG?ref_=nav_custrec_signin&th=1




HHKB USB

Reading:
.471VDC .81A




As you can see the voltage coming out of the HHKB is an order of magnitude less than the other sources.  I'm not exactly sure how it handles current but I think it would be fairly easy to bypass.  I'll have to look online for some HHKB inard pics because as of now I don't want to open mine up unless I know I can mod it.  I'm not sure if the limiter is hardware on the keyboard's firmware istelling the PC not to send the regular 5.0V to the USB.

If it's hardware we can easily bypass whatever is reducing the amount of current coming in, that shouldn't be too hard.  If its the firmware I'd have to get in and look around.  I know there are people here who know the firmware backwards and forwards...I don't know the first thing about it.  I do have a couple teensies laying around and I've been thinking about using them for remapping but I've yet to do that.  Could be a two birds with one stone type situation but I'd rather not have to learn the firmware if I can help it....

Either way it answers my original question, the issue is with the power the HHKB is providing my mouse.

Unless anyone else knows how the HHKB limits the power I'll probe deeper....

[hasu]

HHKB Pro2 uses NEC USB hub chip µPD720114, you can check its datasheet to know whether you can mod it. This is pic of Pro2 controller, not fine enough to read making on chips though.


By the way, don't you have to use another terminal of DMM to measure current?

EDIT: Z8 is NEC hub controller and Z9 is national semi LM3526 power switch in pic above.

[JunkFace]

HHKB Pro2 uses NEC USB hub chip µPD720114, you can check its datasheet to know whether you can mod it. This is pic of Pro2 controller, not fine enough to read making on chips though.

Show Image

By the way, don't you have to use another terminal of DMM to measure current? :D

EDIT: Z8 is NEC hub controller and Z9 is national semi LM3526 power switch in pic above.

Doh!  You are right.  I originally meant just to test Voltage then thought I'd add in current as an after thought to see if maybe it wasn't supplying enough juice.  I'll have to retest when I get home.

My idea is to take a small USB 3 port apart and strip it down to the PCB.  Fit the female usb's into the USB slots, use the mini USB as the power source, Connect the USB port to the female ports out, probably with a ribbon cable, and connect the HHKB in more or less the same way to another usb port.  If I could preserve the original build as much as possible that would be excellent. 

Due to possible space constraints a teensie might be needed. 

I bet that 100ohm resistor is our culprit.  That resistor is probably protecting some delicate ICs though.

[JunkFace]

Without seeing the traces I'd think it would be super easy to isolate the 1 and 4 pins on the outgoing USBS and run a little cable

[ArchDill]

This may not be relevant but my Pro 2 Powers my Logitech M570 pretty well. It is BT. IT is one of the reasons I love using my HHKB for work. For times that I only have 1 USB slot.

[Tactile]

If you're troubleshooting or otherwise dorking around with USB, this tool can be useful.

[Applet]

I would suggest cutting up a usb extension cable and try powering the mouse from the motherboard and using the communication through the HHKB before you start out, just to verify that the power is the issue

I did a quick measurement, and my HHKB-controller outputs 4.95V on the USB-ports with an input of 4.96V (on the usb-mini).

EDIT: Oh, you have the mouse connected and the powerlimiting kicks in during the measurements? Correct me if I'm wrong, but the HHKB sould be able to power 500mA@5V per port, if it the current is avaliable upstream? I tried connecting my Steelseries Xai and it gets 4.8V but won't work, but that mouse is really picky about what I connect it to, so I'm not really suprised.

Not sure if this is of any help tho

[JunkFace]

I would suggest cutting up a usb extension cable and try powering the mouse from the motherboard and using the communication through the HHKB before you start out, just to verify that the power is the issue

I did a quick measurement, and my HHKB-controller outputs 4.95V on the USB-ports with an input of 4.96V (on the usb-mini).

EDIT: Oh, you have the mouse connected and the powerlimiting kicks in during the measurements? Correct me if I'm wrong, but the HHKB sould be able to power 500mA@5V per port, if it the current is avaliable upstream? I tried connecting my Steelseries Xai and it gets 4.8V but won't work, but that mouse is really picky about what I connect it to, so I'm not really suprised.

Not sure if this is of any help tho

I didn't have anything plugged in when I took the measurements. The picture is of my DMM hooked up to a USB I cut up so I could take the measurements easily.  You have the stock  HHKB?  I have two and they're both stock.  I really doubt the measurements would be different but who knows?  My first HHKB was born on August 2014 and my second one is September 2016.

[Applet]

I measured on the stock controller form my HHKB Pro 2, it is not in the keyboard but that should not matter (I'm running a teensy with TMK in the board itself). I don't know the revision of the HHKB, but I can look it up later if you want.

My guess is that, for some reason, the HHKB is limiting the current during your measurements. If you want to measure current, you have to connect the multimeter in series with some load (like the mouse). If you get <0.5V with no load, I would suspect something is wrong with the controller...