Thursday, October 30, 2014

Wireless chargign

I am tired of plugging the charger in my phone. And I'm afraid the socket is going to break soon, seeing as it's about the fourth cable that has broken on me..
So as a solution I ordered a QI wireless charging set. A Note II receiver that claims to have charging current of 500-1000mA at 5V, works up to 5mm from the reciver at the frequency of 100-200kHz with efficiency of more than 70%.

I also bought 2 transmitters. One nice round plastic disk and the other one a bare PCB with a coil.
They both take an input of 1500mA at 5V and claim a 75% conversion efficiency.

And the other one:

The coils are made of strands of coated wire that are about 0.05mm(45AWG). The whole cable is ~1mm in diameter. That's about 300 strands!
It's stranded to increase the surface area to transmit more power.
Unfortunately the receiver's coil is just a copper track on a flex PCB. And has some surface area but not as much.

The charging rate is just average. Gets 460mA through. Not as claimed but good enough, falls in the 70% of 500mA. (The phone is claimed to charge at up to 2A!)

Tuesday, October 14, 2014

Yubikey Neo

So, I have wanted to buy this nifty little device called Yubikey Neo for a long time now.
It does authentication over USB and NFC. Another layer of security for me.

But there has been a tiny little problem. The website said that they'll be releasing a new version 'soon'.
I checked the site today, as I have done irregularly for the last year or so, and finally found out that "Today, Yubico is releasing its YubiKey NEO with support for U2F and delivering it in two form-factors. This key will hold the promise of a significantly more secure online consumer experience, and a dramatic increase in enterprise security and ease-of-use." That was published October 13, 2014. Yesterday.

Well, it was about time.. Unfortunately all of my money is tied up right now. So that $50 purchase will have to wait..

Wednesday, October 8, 2014

Smartwatch update 1

So, Now all I have to do is wait for the components to arrive.
In the meantime: Pictures!
All of them done by hand. No libraries. This will be purely my personal project. At least for now.
Not finished, will tinker with them a bit more. I'll probably publish all of the project when I get a working device that does at least the minimum that I expect it to do.

Smartwatch update 0

So I ordered a few important parts:

No pictures as of yet, too soon for that. Datasheet links will have to suffice.

The mcu was chosen mainly for the availability. I couldn't get my hands on the newer one at any reasonable price. The Nordic Semiconductors seems to be the industry leader right now. And because I wanted an integrated solution this series seemed like the obvious choice. Not the most energy efficient but it'll do.

I also got a ceramic antenna that looked good enough and was also, available to me at a reasonable price.

The charger and gauge for monitoring and charging, respectively. Because I want it to be a one easy to handle unit.

All of the datasheets will be in a later post uploaded to my own hosting server and made readily available.

I have the major parts chosen for now. I will tell more about the development and my choices in a more detailed future post.

Cost so far: 30.57 USD
That's about 24€ out of my 30€ budget.
Probably could have gotten a few items cheaper... but oh, well. 
If I fabricate the pcb myself, that'll be right on the mark. If not, it'll go over by quite much.

20x Neodymium Disc 1/8" x 1/25" Super Strong Rare Earth Magnet 3x1mm
US $0.99

HTU21D Temperature & Humidity Sensor Breakout Board Module
US $3.89 + US $1.74 shipping

5V/3.3V 240x320 2.4" SPI TFT LCD Touch Panel Serial Port Module with PBC ILI9341
US $6.66

Free Shipping NRF51822 Bluetooth Module / Networking Module / Wireless Communication Module
US $6.69

Walsin RF Product 2.4GHZ Ceramic Antenna 1206 (3216) Size LTCC Multi Layer Chip Antenna - RFANT3216090A0T
US $2.00 / lot of 20

MAX1555 MAX1555E MAX1555EZK MAX1555EZK+T , TSOT-5,electronic components ,ICs, &Free Shipping
US $3.20

TDFN8 MAX17043G + T MAX17043 MAX17043G
US $5.40

Smart-watch, first real steps

So I have this awesome idea: A watch-like device that would show me scheduled notifications. And probably time. And for sure log my temperature!
It's mainly to keep me focused and organized. More like an independent device than a smartphone dependent one. It will of course be paired to my smartphone but that's not the main function.
Yeah, lets get right to Hardware.

I haven't decided on the most important part: mcu, the brains.
But otherwise I will have a temperature and humidity sensor touching my skin, an accelerometer that senses up to 1,5g, to react to me bringing my arm up and tapping the device -- the wake-up gesture.
Also a 2.4" qvga resistive touchscreen lcd with dimmable led backlight :p
So far these are all serial devices. So I won't have to have a huge mcu on it. Just a relatively powerful one.

I want the thing to have Bluetooth, preferably 4.0 low-energy. And I wouldn't mind the mcu being together with the wireless in one chip. It'll keep the footprint smaller.

Right now I have an old 550mAh lipo that has nice dimensions, I'll try to find a new one that's the same and design around that.
I'll have to do a lot of power management to keep the power stable and the requirements really low.
I thought about including wireless charging but that would make the device too bulky.
I have plans to fabricate the pcb myself out of a thin strip of plastic and some copper foil. A two sided sandwich.

I want to have the temperature sensor touching my skin, so on the underside, opposite of the mcu. Then I want the 4-5 magnets in each corner and maybe in the center. So the bottom of the pcb would be routing and ground plane. Every other component will be on the topside.
I want to have the space under the screen divided in half, one side for the battery, other for the pcb..
Out of the same thin copper foil I use for the pcb, I want to make a case. It won't have to be sturdy, just nice looking. Maybe also a thin protective cover for the lcd, I'll see how well the resistive touch plate handles any obscuring objects.

Overall I am expecting it to be around 7mm or less, without the magnets(they'll be only 1mm anyway. With a diameter of 3mm.) We'll see :D

Bought so far:
The display
The temp sensor
The magnets

The accelerometer comes from an old Creative X-fi 2 (The same place as the battery xD)

What I have done so far:
Packages and devices in eagle for all of the mentioned devices. The touch controller, the humid/temp sensor and the accelerometer.
A lot of planning on paper, in my head and modeling out some of the components.

Next time:
Pictures, part names and datasheets.
An mcu announced.
Communications planned out.
A bit of the algorithm done.
Ideas for the user interface.

Monday, October 6, 2014

I got lazy

So, I created this blog to talk about many projects that I have going on,  And apparently I only talked about 2 of them.
So here we go:


I am currently designing a smart-watch for my own purposes. It's going to help me keep organized by me scheduling my days notifications and this device displaying them. It's going to be really intrusive. It'll log my temperature and skin humidity, have a vibrating motor to notify me and a led to shine a bit of light. Maybe also a gyro.. It'll have a 2.4" touch screen, be mounted to my wrist with magnets that I'll at first glue to my skin and then later have 4-5 small titanium piercings that have a flat top (Idea comes from a few years ago here). It's going to have only one button, which wakes it up. Probably a thin self-made pcb and a lipo battery. Interfacing is done by usb and bluetooth. It's going to have a cradle that charges it. Probably also an adapter wire.

old LCD picture frame

So I have this old laptop that broke.. And it's now so broken that it takes more effort to keep repairing it than just scraping it. So I scrapped it and got this nice lcd panel that I am going to turn into a picture frame running android. Basically a tablet, not that I don't have a useless tablet already but this one is bigger and will have a purpose in its life: Picture storage and showcase.
It'll be of course controllable over wifi by another computer or smartphone..

bench-top power supply

I have been using an old 350W atx psu so far.. And it has served me good. But I feel like it's about time to give it a new life as a nice controlled bench psu with all the bells and whistles. A few buttons, rotary encoders, a display, a microcontroller and some control circuitry. Also a nice case :)

three monitor stand

I have been using 3 monitor for the last 3 years and they have always irritated me with their huge bases. So finally I'm going to do something about it. I already have debezeled them, I have nearly all of the components I need and it's just on hold because I'm lazy.

bigger desk

I moved. While moving I got new furniture, And because it was cheap, a cheap desk. It would be perfect for studying, it's 0,5 x 1,23 m ... But I'm a engineer with a workstation,3 monitors and need more workspace. So a new self-made custom desk is in the works.. More like being designed right now. And it'll take some time to actually get to making it because well.. Money.


I have a plan to fit every room in the apartment with speakers. Individually controlled and networked together wirelessly. Probably a server to control them all. Also I want to be able to control all of the lights wirelessly, all of the power outlets and some monitoring of when I'm home and in which room each person is. The system will include also heat control: I have a plan to install an array of fans under each radiator to siphon more heat from them faster. So I could sense the temperature of the room and regulate accordingly.

new soldering iron

I have made do with a really crappy Chinese "soldering station" that has a whooping one knob to "control temperature". So for the longest time I have wished to have a nice new quickly heating and temperature controlled soldering iron.. Unfortunately I am too poor to cash out a few hundred dollars for a real one. So I am going to make one myself. Probably a hakko iron, self made controller and a beefy power supply.. Shouldn't be too hard. I only have a mockup of a pcb so far. I haven't even decided if I want the fancy T-series or a regular 907...

PCB drill press

I am in a need for a really precise drill press that I could drill pcb vias and other holes with. So my only natural solution is to make it myself. Unfortunately it'll be a manual one, I don't have room for a CNC one. I'll make it out of linear bearings, a metal stand with a leaver and of a fairly powerful motor for its size. I'll have to design a custom chuck, probably something like Dremel uses..

And yeah, that's it for now. Not done with the projects list but those were the major ones that I hope to get done sometime for sure. I have a lot of ideas, about a hundred projects on my mind and some written down.. I just can't be bothered to write them all over here.. Maybe sometime in the future I will take time to make a nice list of all of the projects and ideas I have going on.