Cheap power banks and why don’t they charge my Samsung S4 Active

Yesterday I bought cheap iWalk branded power bank to make my Ingress (read – working out) sessions last longer and to my dismay this power bank did not charge my phone while I played Ingress. Since not so long ago I developed this universal USB charger, I am well aware that at large charging currents (1A and more) there is quite a bit of a voltage drop in USB cable and at least modern Samsung phones sense this drop and reduce charging current. I cracked open iWalk and no surprise there, output at USB connector on bank side was 5.06V. Solution to this problem is to bring up output voltage to about 5.2V, which is still within USB specifications, but compensates for the voltage drop caused by thin USB cables.
Luckily iWalk used two easily identifiable adjustable switching step-up converters with resistor voltage divider feedback network, so all it takes to fix the issue, is to replace those resistors with new ones and see if that helps.
Stay tuned while Farnell delivers my resistors, once that happens, I promise to write a new blog post with some images.

Update – apparently that post I promised is not going to happen because there is something fishy going on with that power bank and I do not have time and/or will to figure what exactly.

Magento – Footer links in different languages, how?

This is question many ask and there is non-obvious, yet simple and elegant answer – you can have multiple static blocks with the same identifier – create separate static block with identifier “footer_links” for each store view and you are done.

Lūdzu sagaidiet – Magic Smoke Refill Labs!

Virsraksts visu izsaka – Magic Smoke Refill Labs ir uzņēmums, kura mērķis ir nodrošināt Latvijas “urķiem” vieglu un ātru piekļuvi elektronikas izstrādes platformām un vēlāk arī sniegt ar elektronikas prototipēšanu saistītus pakalpojumus.

Dear Atmel, Texas Instruments, Intel,…

… you all are big companies, you all say you support makers and hackers alike and you all are members of USB-IF. Maker community has a problem with USB-IF, which is probably best described in this blog post by Nick Johnson, so I thought, you, as members of this organisation and as supporters of maker community, could help convince USB-IF executives to be more open-minded and collaborative?

Thank you in advance,
Raivis Rengelis, one of makers

eID + Ubuntu 13.04 + Chrome/Chromium

1. Jāpierunā Ubuntu saprast karšu lasītāju, lai to izdarītu:
sudo apt-get install pcscd pcsc-tools

2. Pārliecinamies, ka karšu lasītāju sistēma atpazīst


3. no savācam un atpakojam sev ērtā vietā (un kāpēc tas nav deb?)

4. no sev ērtās atpakotās vietas zem root nokopējam opt uz /opt

5. atkal jau zem root no sev ērtās atpakotās vietas palaižam
DEBIAN/postinst configure

6. pārliecinamies, ka nekas nestrādā, jo pietrūkst mazliet vecākas libssl versijas, kā ubuntu 13.04 nāk komplektā pēc noklusējuma, tāpēc:
sudo apt-get install libssl0.9.8

7. pārliecinamies, ka nu jau kaut kas strādā

8. un nu to visu beidzot vajag pieskrūvēt Chrome/Chromium
sudo apt-get install libnss3-tools
modutil -dbdir ~/.pki/nssdb -add "eID Module" -libfile /usr/lib/pkcs11/ -mechanisms FRIENDLY

9. importējam LVRTC saknes sertifikātus Chrome/Chromium no

10. lietojam eID parakstu ar Chrome/Chromium visur, kur vien to ņem pretī, piemēram

NB! “User PIN” ir PIN1 un “Signing PIN” ir PIN2

TCS34717 break-out or #SecretProject revealed [updated]

Jayson Tautic of TAUTIC ELECTRONICS LLC has teased his followers on twitter with some #SecretProject for a while and today was the big revelation – that is TSC34717 color/light sensor breakout.
Chip itself is a nice little gem by ams, first, it looks cool, second, it is capable of measuring R, G, B and overall luminosity with 16 bit precision each and has high dynamic range.
But there is a catch – it has weird power requirements, 3V supply and 1.8V I2C bus and it is very small. I made a decision to make the breakout 3.3V-5V compatible, so that it can be used with most popular development boards out there. Yes, I made that decision, because that was me who designed the breakout and pushed Jayson into producing and distributing it. Reason for not doing that myself is that I live in Latvia and small production runs of things like this is way more expensive than doing the same on the other side of Atlantic.
So there you are – 16bit color/light sensor with high dynamic range, compatible with 3.3V-5V hosts and communicating over I2C.
After getting first working prototypes done, joint decision was made to go on tindie with fundriser. That would let us find out if there is interest in this sensor and hopefully fund first production run. Meanwhile, I am working on Arduino library, so that break-out is usable from the day one with ever so popular prototyping platform.

The cool thing about this project is that I live in Latvia, Jayson lives in the USA and we have never met in person. Our only contacts are on internet, on twitter and tymkrs IRC.

the board is now on tindie – TSC34717 break-out fundraiser

Rye bread

Original is from (give credit where credit is due)

0) Acquire rye flour, the coarser the flour, the darker the bread will be

1) Leaven
50gr of flour mix with 50gr of water, leave in warm place for 24h. On next day add 50gr of flour and 50gr of water, leave in warm place for 24h. Repeat for 3-4 days. At the end of 4/5th day you should have nicely fermented leaven.

2) First dough
Take all leaven you have from step 1 and mix with 4 cups of flour and 3 cups of warm water. Leave it to ferment for 5-8 hours, if it is relatively cold in the room, it may take longer. Perfect place for fermentation is heated floor. Dough is ready when it is full of bubbles and raised (check pictures in original post).

When first dough is ready put aside 2 cups of dough in fridge (above freezing temperatures), that will be your leaven for next batch of dough. Leaven can be left in fridge for up to 2 weeks. When ready for next batch, take it out of fridge, let it warm up and start from step 2.

3) Second, final dough
Take dough from previous step (less leaven you put aside), add:
4 cups of flour
6 tablespoons of sugar
2 tablespoons of salt
2-3 tablespoons of honey
2-3 tablespoons of cumin seeds
3-4 tablespoons of sunflower seeds
4-6 tablespoons of linseeds
4-6 tablespoons of pumpkin seeds
All those seeds are matter of taste and you can leave all of them out of recipe or add some other seeds or nuts or dried fruits to your taste.

Mixing it all up – take few tablespoons of water, dissolve honey, salt and sugar in it, add it to first dough, mix in and then add flour.
Leave ready dough to ferment for 3-5 hours. It should fill with bubbles and rise.

From ready dough form two loaves, sprinkle with flour, coat with oil, sprinkle some sunflower seeds on them, put loaves on baking paper.

Baking – preheat oven to 350°F, put your loaves in and bake for an hour and 15 to 30 minutes (experiment here). When bread is ready, take it out, slightly wet it with water using hands, wrap in clean cotton or linen towel, put it in plastic bag for 15 minutes, then take out of bag (but leave in towel) and leave your bread to cool down.

Never eat rye bread hot, it is not as tasty and good that way, in fact, the older the bread, the better it becomes.

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AS3935 breakout and Arduino library on DesignSpark

Thanks to Andrew Back my AS3935 Arduino library and Jayson’s breakout board are featured on DesignSpark (ok, I know, first was the board 🙂 ).
For Prop fans, there is Propeller Object by Randy.

AS3935 Franklin Lightning Sensor™ + Arduino

Just a short post.
1) AMS made a nice lightning sensor chip AS3935
2) Jayson Tautic from TAUTIC ELECTRONICS LLC made even nicer breakout board
3) I made Arduino library to make use of AS3935 easy on this ever so popular platform
4) and tested it on Arduino Mega 2560 and chipKIT MAX32

The code (hopefully) works with most of original boards and clones.

Here is the link again, just in case you missed it –

cheap signal generator? yes please!

Who does not want a VNA and/or Spectrum Analyzer? I do, but those are a bit out of my budget right now. But I still want to play with some loop antennas for the project that is in the works, so I need a way to measure loop antenna parameters. How is it done? Well, you put known signal into loop and measure response, that’s what VNAs and SAs do, but those are expensive…

Cheap AD9850 breakout to the rescue. China made AD9850 breakout boards are available on eBay for ~6USD shipped (I wonder how they do that if chip itself costs ~15USD in 1000 quantities from DigiKey). Those things are capable of putting out 0-40MHz in sub-Hz steps of quite nice and clean sine wave, but you need a way to control them. And so “somewhat useful” Arduino sketch was born. It uses AD9850 library from ELECFreaks, one can set specific frequency with it, make AD9850 sweep through frequencies tracking generator style or sweep through frequencies in oscillating manner – back and forth.

It is probably good for testing AD9850 breakouts too, enjoy – somewhat useful AD9850 Arduino sketch.

A bit of background info. Serial control is used, see the datasheet what pins need to be pulled up and what pin needs to be pulled down to enable that and since there is no information on module available, some nice guy called Andrew Quinn has documented pinout of these little neat boards on his blog.