Dawnmist

This is a quick post to record the changes I needed to make to the Bluetooth driver for an Edimax EW-7611ULB wifi & bluetooth usb dongle to get the bluetooth working on the (currently) new Raspberry Pi 4.9.11 kernel. Hopefully it can help anyone else using this adapter when they upgrade their Raspberry Pi.

The original instructions and source for installing the drivers for this adapter are published by Edimax themselves at: https://edimax.freshdesk.com/support/solutions/articles/14000047172-how-to-install-ew-7611ulb-adapter-on-raspberry-pi - but they currently cover installing the drivers for a Raspberry Pi running kernel 4.4. The wifi driver installation documented by Edimax works fine. There is one minor modification to the bluetooth driver source code required so that it will compile properly due to kernel api changes in kernel version 4.9 for the HCI driver interface.

In Section "(II.) Bluetooth Driver Installation", before running "sudo make install -s", you need to edit the file bluetooth_usb_driver/rtk_coex.c. At line 448, change

#if HCI_VERSION_CODE >= KERNEL_VERSION(3, 10, 0)
#if HCI_VERSION_CODE < KERNEL_VERSION(4, 4, 0)
	bt_cb(skb)->req.start = true;
#else
	bt_cb(skb)->hci.req_start = true;
#endif
#endif

#if HCI_VERSION_CODE >= KERNEL_VERSION(3, 10, 0)
#if HCI_VERSION_CODE < KERNEL_VERSION(4, 4, 0)
	bt_cb(skb)->req.start = true;
#elif HCI_VERSION_CODE >= KERNEL_VERSION(4,9,0)
	bt_cb(skb)->hci.req_flags |= HCI_REQ_START;
#else
	bt_cb(skb)->hci.req_start = true;
#endif
#endif

Otherwise, follow the instructions on the Edimax link to get both wifi and bluetooth working properly with this adapter on the Raspberry Pi.

I think I've worked out what my next build-it-yourself project will be...a replacement to a mouse that can be used with fingernails instead of having to hold it. I have an auto-immune condition (Sjogren's Syndrome) that is causing the skin of my hands and feet/legs to burn/sting fairly badly (the Sjogren's is causing Small Fibre Neuropathy). My hands were hurting enough by the end of the day today at work that I couldn't really hold my mouse anymore. Pressure on the skin - particularly against ridged objects like the scroll wheel - aggravates the Neuropathy issues...and between the palm holding the mouse to move it and the scroll wheel and buttons on the mouse poking my fingers it becomes very hard to use the mouse when my skin is feeling like I've skidded on my hands across asphalt. My hands are not like that all the time...yet...but I can see a future when they will be, so I've decided to design/build an alternative device for me to use instead. I've found that typing on my fingernails doesn't trigger/aggravate the pain in the skin of my hands, so I'll design a replacement device for a mouse around being able to use my nails as the primary input device instead.

A thumb-ball trackball wouldn't really work either - you still use the fleshy pads of your fingers/thumb to move the ball, press buttons, etc, and to move the scroll wheel if it has one. It likely wouldn't aggravate my palms as much, but that's about all I could say would be positive about it. A palm-ball variant would be even worse.

So I'm thinking I'll build a box with 5 keys in a cross-shape. Left/middle/right click across the horizontal, with scroll-up above the cross and scroll-down below it. Behind those on a 90-120 degree angle I'll mount a resistive touch sensor - resistive so that it reacts to fingernails - to use to replace the "ball"/movement part of a mouse. About the only thing it wouldn't do easily would be click-and-drag...but that would be more a case of learning alternative finger use/positions than anything else. Or I could use another key as a "toggle left-click"...i.e. it stays "clicked" until pressed a second time. I'll have to think a bit about that...it's an easy solution to the issue.

I know where I can get the keys and keycaps easily, and the controller to use to turn those into a device that any PC will recognise as a USB mouse. I think I could probably use an instrument case (the kind with the angled end for a LCD to be mounted in it) as the box. I just need to find the resistive touch sensor to put on the angled back (there's a lot of cheap ones pre-mounted on TFT screens, but I don't need a screen for a mouse).

My circuit board arrived today, and on initial inspection looks good. I got lucky and received 3 copies of the board. There are one or two minor blemishes in the flood-fill ground copper, but all of them are in large areas and not in places where there were tracks or anything critical, so those won't matter.

Fits nicely in the box, the keys mount properly (not so tight that you have to force them, but firm enough that it takes a bit of pressure and the posts will lock them in place and prevent rotation), the Teensy fits (plugged in from underneath), and the connectors fit well.

Next thing is to actually get the components soldered onto the board - and find out whether I screwed up the circuit...We did try really hard to check it before sending it off to be made though, so I'm hoping it all just works. :-)

I spent most of the weekend (when I wasn't blinded by a migraine) laying out a (potential) circuit board for my home-made keyboard. At the moment, it's still wired up via breadboard taking up a ton of space on my desk - I'd like to finally get it inside the keyboard box. :-)

First attempt was a daughter board for the shift-register part to connect to the existing keys...but wasn't going to fit the teensy & 40-pin screen connector in the space at the end as well, which would still leave some of the keyboard parts sitting outside the box.

Second attempt was a complete replacement of the existing key mount for the 24-key section of the keyboard, integrating them onto a single circuit board so that the teensy & screen could go on the other side of the keys, and the keys could be directly wired to their shift registers instead of needing connectors for them - that looks a *lot* better in terms of wiring, and has all laid out nicely so far. I've still got a few adjustments to make - the joystick needs wiring in, and there's a couple of resistors we need to add as short-circuit protections for the footswitch & spare button connectors, but it's looking like it'll work nicely.

I discovered that circuit board layout is a really interesting and fun puzzle to do...and one that will actually be useful at the end, which traditional jigsaws generally are not! *lol*

I've been doing a lot of work again the last month on my upgrade from using a Teensy 2++ with monochrome screen to a Teensy 3 with Colour TFT + SD Card + Touch, and it's now coming together nicely.

So there's still lots to keep me busy, but in the mean time - the basics are now all there and working together well enough to ditch the Teensy 2++ controller for the keyboard and move across to using the Teensy 3 controller full-time!

I received my Teensy 3.0 controllers in the mail last week, so I could finally start on version 2 of my programmable right-hand gaming keypad (designed to sit under my right hand because my mouse is on the left - my right shoulder doesn't tolerate mouse movements). I got the real time clock working, then the sd card...but for the life of me I simply couldn't get the Tft screen to work.

All that frustration/hair tearing out was due to an incorrect specification of the controller on the tft. Just in case someone else comes across it, if you bought a 3.2" tft from ebay claiming to use the HX8347-A controller and it just won't work, try treating it as the SSD1289 controller instead - it seems that some ebay sellers have been listing their tfts as having the wrong controller chip!