Saturday, July 7, 2018

Disassembling a Bluetooth speaker

As you may have noticed from my previous post, I am a fan of disassembling devices with the purpose of learning.

I got this nice Bluetooth speaker as a present from Redhat during a conference in Japan. It works by pairing your phone with the Bluetooth speaker to play music. The speaker provides three push buttons (volume down, play, volume up), a USB interface to charge the battery, a power on switch and a microphone.

The speaker's body is made of ABS plastic and covered by a rubbery silicone wrapper with a nice matte finish. The wrapper has a suction cup to stick the speaker to a surface. Let's look inside.

The body is held together with screws. The speaker and the microphone are glued to the top part. The printed board has pads for an extra microphone and LEDs. I suppose they left them there to customize the final product depending on the price. Finally, the lithium battery is glued to the bottom part.

The speaker is connected to the chip at the lower side of the board, an LTK8002D audio amplifier made by LTKCHIP TECHNOLOGY (ShenZhen). The brains of the Bluetooth speaker are implemented using the AC1533D83234, an SoC (System on chip) made by ZhuHai JieLi Technology (Zhuhai City). From what I could see by inspecting datasheets of similar chips, it (probably) contains a 32bit RISC CPU, GPIO pins, PWM, ADC, DAC and Bluetooth capabilities.

Conclusions: the way the Bluetooth speaker works is quite easy to understand. First, the SoC gets its power from the battery through a voltage rectifier (on the top side). The SoC also uses an external oscillator circuit to generate its own clock signals. The 3 buttons (and LEDs) are connected to the GPIO pins. When the switch is on and we press the play button, the SoC will receive audio data from our phone through the Bluetooth antenna which is printed onboard. Then, the SoC will convert these audio data into an analog signal, adjusting it to the current volume level. Finally, the SoC will forward the signal to the speaker through an audio amplifier. The most interesting part from disassembling this device has been finding and reading the website of ZhuHai JieLi Technology (thanks to Google translate!). I didn't even know this company existed. I wonder how many more companies and chips from China are left for me to discover.

Wednesday, July 4, 2018

Pinguchan: Let the game begin!

A year went by since I published my first children's book. Today I am publishing my second one: "Let the game begin!".

This book is quite different from the previous one:
  • I created it completely on my computer, using Clip Studio Paint.
  • The artwork has a very different style and was created under time pressure.
  • It contains 34 pages in total (the previous one had 15).
  • It is distributed with a free license (CC By 4.0). For example, any individual, schools or commercial publishers can freely modify, print and distribute the book as long as they satisfy the "attribution" condition in the license.
  • Anyone can download the book for free in PDF.
  • And more importantly, I got the help of many amazing friends who translated the book into their native languages. One of my goals was to get the book translated into languages with a small speaking community. Those languages aren't usually commercially attractive compared to major languages (e.g.: French or Russian) and for that reason, many families can't read books to their children in their native language. If you are interested in contributing a translation please put a comment below this post or send me an e-mail.
Please, download the book in any of the following languages:
  • Spanish es_ES (PDF), original work by Daniel Sangorrin
  • Japanese jp_JP (PDF), translated by Misaki Sakashita
  • Malagasy mg_MG (PDF), translated by Andoniaina Andriamiandrisoa
  • Bulgarian bg_BG(PDF), translated by Strahil Pastuhov
  • Basque eu_ES (PDF), translated by Borja López Vicente
  • Korean ko_KR (PDF), translated by Hee-joon Woo, reviewed by Song-yi Baek
  • English en_US (PDF), translated by Patty Tiburcio
  • Taiwanese zh_TW (PDF), translated by Liya Su
  • Polish pl_PL (PDF), translated by Tytus Wojtara
  • German de_AT (PDF), translated by Tytus Wojtara
  • Uzbek uz_UZ (PDF), translated by Sherzod Zakirov
  • Portuguese pt_BR (PDF), translated by Koichi Aizawa
  • Chinese zh_CN (PDF), translated by An Haixing
You can see below a few pictures from the creative process and some initial sketches with characters that never made it to the final book:

I am a volunteer for a local group that promotes multiculturality by reading children's books in multiple languages. For example, here I am reading "The very hungry caterpillar", written by Eric Carle, in the Spanish language.

 Being able to read your own book and see the reactions of children is an amazing experience.

Conclusions: first, I would like to thank my friends for their altruist translations. By comparing different translations I could learn many words and realized that all the effort spent in the translations was really worth it. Second, despite the time pressure, I think I managed to deliver a nice children's book. It is true that I cheated sometimes and copy-pasted some of my artwork multiple times, but overall I think the result is good. I have to say that I am really enjoying the experience of reading my book in front of children and families. Finally, it would be really great if the book was used by schools or individuals around the world. I want to promote the minor language versions as much as I can.