$10 China Handset

[oakkar7]

Last year, I saw Bunnie’s blog post about a cheap $12 Gongkai handset from Mingtong Digital Mall in Shenzhen.  Gongkai means “Open” in Chinese and it’s the term alternative of “Open Source”. Mingtong Digital Mall is one of the famous digital gadget’s malls from Shenzhen especially cheap and copy items. I wondered how these cheap handset could be sold in this low price when I saw his blog post.

www.bunniestudios.com/blog/?page_id=3107

And Dave tear down  $5 Mobile Phone Teardown - LG800G,

https://www.eevblog.com/forum/blog/eevblog-514-$5-mobile-phone-teardown-lg800g/

Yesterday, one of my colleagues showed me a GSM handset with a surprised price tag, 10000 MMK (I live in Myanmar).  It is about $10 (1$ = 986 MMK). I quickly checked specs and my curiosity leaded me to bought one and tear down it.





The brand is Soloking and model is T176. I quickly searched google for more info.
superfone.en.alibaba.com/product/1807438912-215027443/T176_1_8inch_soloking_china_mobile_phone_cheap_price_celulares.html

Platform                       : coolsand 8851
Operation System      : Mstar
Build in memory        : 32+16 Mbt
Frequency                    :  GSM 900/1800   optional   850/9001800/1900
Multi Media                 : MP3/MP4/3GP/FM Radio / Bluetooth Camera 0.3 Mega Pixels
Multi Function Torch : Alarm ,Calendar ,Calculator ,Audio recorder ,Video recorder
Flash Card Support     : T-Flash Card Max support to 8GB
Languages Multi language : Arabic,French,Turkish, Thai,Vietnam,Russian, English, Hindi, Indonesian, Spanish etc

Other are usual parts such as speaker, mic,  SIM holder, SD slot, small camera, FM antenna and 2 x LEDs for torch. The phone is controlled by all in one chip.  The back side Speaker housing is attached with multi-band antenna.

- LCD, this must be a friendly 1.8" SPI TFT, LCD  (ST7735 controller ) from hobby shop around the world. I even ordered these LCD from elecfreaks
http://www.ebay.com/itm/1-8-Serial-128X160-SPI-TFT-LCD-Module-Display-Screen-PCB-Adapter-w-SD-Socket-/200764741074

- There is a EMI shield which covered the chip but google infos and some partially label can able to guess  me the main chip. It is RDA8851 from RDA Microelectronics, one of chip manufacturer from China. In short, it’s all in one chip which doo everything for phone such as baseband, interface, Bluetooth, FM, camera, Flash (32Mb build in), UART, SPI, I2C etc. Here is the links to chip datasheet.
www.rdamicro.com/products/Detail_238.aspx

- Firmware is Mstar from MStar Semiconductor, Taiwan . From  Wiki , MStar is often referred as “Little-M” in Chinese community, as a contrary part of the bigger company “Big-M”, MediaTek.
www.mstarsemi.com/
www.mediatek.com/

Final thought:

- First, I don’t expect much from this phone but the price is really amazed for me. It is a bare phone without no contract and unlocked. It exported from china to Myanmar. What will be local retail price and how much it can be lower?

- The cost of the phone is the parts and production costs plus a little export costs. There will be absolutely NO licensing, copy cats fee and seem no certification.

- Everybody talks about SAR. But I think the RDA chip can take care of this in a basic level. The package label state that SAR Head : 0.342 W/Kg(1g) and body : 0.429 W/Kg (1g).

- I know that designing a mobile phone is not that hard. I designed my own DIY mobile phone recently with a basic functions like this phone with the same LCD. Even LCD it self costs about $6.4  in some ebay retail shops. What will be the lowest bargain price of this LCD? (I believe the LCD must be the most value part in this phone. Any idea?)

- For the chip, I don’t know how much cost for this RDA chip in volume and in retail. Bunnie said that MT6250 chip from his Gongkai Phone in retail price is $2.1.

- If someone knows about these, let me know and also share your thought.

More detailed in my blog,
http://okelectronic.wordpress.com/2014/10/03/10-china-gsm-phone/

[SeanB]

You forgot dual sim card operation as well. Not a bad phone, like the now out of production Nokia 1100 I was using for a while, which was $15 retail when I bought it. That though did not have colour LCD or a camera, but had single sim and no expansion memory, but had the FM radio and the torch.

Those would be perfect here, simple, long battery life and a FM radio ( lacking in all US phones though the receiver is in there and is software disabled for some reason I cannot fathom) along with simple VGA camera and video capability and a way to play non DRM music, with enough space for a few weeks of songs. fits the market price point as well.

[oakkar7]

Yes SeanB,

- Dual SIM, actually it is dual standby

And more,
- like many budget phone, it supports java
- camera is mentioned that >3M pixels but quality is sucked  but it is acceptable in this price tag
- GPRS Class 10

RDA8851 is an interesting SoC chip. Everybody said about SAR but IMPO the chip can take care of this in a basic level. The chip supports (not my handset)
- USB 1.1 Device
- Touch
- 1.5W differential output stereo amplifier for loudspeaker, Class K
- Battery charger (from USB or AC charger)
- Triple SIM controller with integrated level shifters 
- Support LCD module interface with 8 bit parallel interface or SPI series interface  Support up to 480X640 resolution
- 4-layers blending graphical engine capable of resizing and YUV2RGB conversion
-  Proprietary 16/32-bit digital signal processing engine to improve computation performance
-  2 UART interface (i am thinking of tapping one and making a hacked GSM/GPRS shield 

The phone is working well comparable in this price line. The only flaw is it's charger. It voids all safety rules. No protection in both Hi/Lo sides at all, not even a fuse.
It is no need claim in this price but I used it only with a another charger.