$10 China GSM Phone

We have seen how new Iphone shakes the market. How about low tech phones  and how much a handset cab be cheap? 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.


I lived in Myanmar, yes a green land opened it’s door recently. The government released telecom sector and has given the two new operators, Telenor and Ooredoo. Just a clarification, some may don’t know how Myanmar telecom sector is squeezed before 2000. I bet you will wonder how much it will cost for a mobile SIM card before 2000. It was cost about $5000 (Please up your jaw, I am not kidding :D). In last decade, owning a mobile phone was a trade mark of being a “boss” in Myanmar. Most people used a public pay land lines phone booth in every sight of cites. Seem these will soon be a history. But for now, news operators are moving and it costs  about only $1.5.

Have you ever seen people queuing for a cheap SIM card?


Yesterday, one of my colleagues showed me a GSM handset with a surprised price tag, 10000 MMK.  It is about $10 (1$ = 986 MMK). I quickly checked specs and my curiosity leaded me to bought one. It is a normal low price GSM handset with basic functions. I saw many cheap China handset but non are not lower than $20. This is the cheapest handset I have ever seen. Note that Bunnie’s Gongkai Phone is $12 at China, main land but I bought my $10 phone from local retail shop from Mandalay, Myanmar. More surprising fact is that my friend told me wholesale price is >$9. If this is right, how much it will be the ground cost of these handset in it’ts origin, China!! Unbelievable. Here is my cheapo handset. It is just ordinary phone but specs are even a little higher than Bunnie’s phone come with a box, handset, a battery, charger and a hands free earpiece.

DSCN7341 DSCN7344


The spec and functions listed on the box,

  • Touch
  • FM Radio
  • Music Player
  • Video player, recorder
  • MicroSD
  • Camera
  • Bluetooth
  • Multi languages
  • 1.8″ Display
  • Dual SIM (Dual standby) , Stereo Speaker (Really, only one Speaker), Games

DSCN7342 DSCN7343


The brand is Soloking and model is T176. I quickly searched google and searched 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

I installed battery, SIM and power up the phone.



Tested basic functions call, menu, camera, FM etc. DSCN7352 DSCN7356 DSCN7359

– FM


– It supports Java.


It even include Myanmar language support. Changed and tested it but some menu were not properly show 🙂 .

DSCN7357   DSCN7358

Finally, I teared down to check how these cheapo was made.

DSCN7363 DSCN7345

Just removed 4 x small screws, everything disassembled.

DSCN7366   DSCN7374     DSCN7369 DSCN7372


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  last a few months ago.
  • 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.

– The only weakness of this phone (in comparable this price) is it’s charger. I also opened and checked the charger design. It voids all of safety rules. Manufacturer should include a more safe charger with a buck. The stock charger is one of the simplest and reduced version without any protection of it’s line. The design includes 13001 NPN Epitaxial Silicon Transistor,  1 IN4001 diode rectifier, small SMPS transformer, 5V zener, 3 capacitors and some resistors, that’s all. The output voltage is about 6V.


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.

Last :

Again, it is not rocket science to build a mobile phone. This is my DIY GSM mobile phone prototype which I recently developed for fun and hobby. Some basic functions such as call, sms, GPS are done and still working for a complete prototype. But, you may not defeat China at least in quantity and cost :D. Thanks for visiting.


By oakkar7


GTP-USB-Lite Programmer re-flsahed as USBPICProg

I bought this programmer from local supplier a few years ago. This is a GTP-USB-lite programmer clone and beautifully build as sandwich  style.

USB-PIC_Prog (2)


USB-PIC_Prog (3)

Some drawbacks of this programmer are:

  • I noticed that this programmer don’t work with some PC/Laptop USB port for unknown reason.
  • Don’t support Windows 7
  • Not opensource,


Anyway, GTP-USB programmers are the best and DIY friendly at their age. Mostly, I used PicKit2, PICKit3 as main programmer. So, I leave this programmer in a corner of my desk for a while. Last week, I noticed a post in DP forum about hacking aka flashing this programmer.


The original blog post here.


At the last weekend, I try to flash my GTP-USB-Lite programmer with new firmware and to use new software. The procedure is very simple.

– GTP-USB-Lite and USBPICProg are very identical hardwares, USB interface, PIC18F2550, the same charge pump, same programming header’s pin.

– The difference are;

  • GTB-USB lite used 8MHz crystal and USBPICProg uses 12 MHz crystal
  • LEDs are connected at PIC pins 11,12 and 13 in USBPICProg and pins 27,28 at GTP-USB-Lite.

GTP-USB-Lite hardware circuit

USBPICProg hardware , firmware, PC software (The best thing is  all are opensource :D)

– First, to take off and flash programmer’s PIC18F2550 with boot loader and to change 12MHz crystal in circuit

USB-PIC_Prog (4)



– Download and installed PC software and install it.

– Download last firmware and  attached programmer. The PC will detect bootloader and install bootloader USB interface driver. Launch the PC programmer software and  bootloader is activated and update firmware.

– USBPICProg-0.6.0-software –> Updated Firmware

– Then, remove programmer from USB port. Connect PGC pin (RB6 , Pin No 27 of PIC18F2550) to ground to de-activated the bootloader and activated USBPICProg programmer mode. The PC USB port will detect and installed new device (USBPICProg) driver.

Before final launch, I simply cut the trace between LEDs and  RB7,RB6 (pin 27,28) and connected LED’s resistors to Pin 11,12. LED shows signal now.

USB-PIC_Prog (1)


For now, I can use reborn USBPICProg as a backup programmer. I renamed it USBPICProg because it is no more GTP-USB Lite.






Microchip Advanced Parts Selector and other handy tools (Online/Offline/Mobile vers)

I used PIC as my primary development platform for years. Selecting a right MCU and checking features while developing is a time consuming task sometimes. Last week, I noticed handy tools in Microchip website.

The first tool is Microchip Advanced Parts Selector (MAPS) tool. There is online and also offline version. I tested both quickly. Online and offline version are same interface. Great, can search, filter and compare various PIC easily.

The link : http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1924&dDocName=en544123


There is also a mobile version for both Android and IOS platforms named Mobile Product Selector.  It is also handy to use with your tablet at workbench while testing something.

Android App Link: https://play.google.com/store/apps/details?id=com.microchip.andriod.mmps&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5taWNyb2NoaXAuYW5kcmlvZC5tbXBzIl0


Wait, there are also some good tools for discrete components, Analog and Interface Products Presentation – (Offline Only). This is a power point file with good linking. You can click and find right info for interface , analog peripherals and  parts like transceiver, op-amps etc..


Last one is “Product Tables”, all PIC with required info and volume pricing can be downloaded as PDF or CVS format.

Testing MPLABX and Open Bench Logic Analyzer (part-2)

The previous post is about the installation, developing and programming of logic analyzer testing circuit with MPLABX. Now, it is time to test with my new OBLS. Connect all input test connectors with PIC PORTB pins and also ground. Power up the circuit.

First, I tested the circuit with oscilloscope to sure the code and circuit are working. Good, output signals are generating. I tested all pins of PIC PORTB. As expected, pin-1 output frequency is twice of pin-2, pin-2 also twice of pin-3 and so on.

There are several of client software to use with OBLS.

I don’t want to use .NET and python. Sigrok is not released yet. RCP client is still initial phase but has some distant features such as frequency and distance measurement.  I also prefer cross platform feature. So, I tested SUMP client and OLS client.

The SUMP client has a installer and installation is straight forward. I like the installer from Gadget factory. There is the original client here but I don’t want to mess with RTTX dependency (used for java serial port support).

For some clients, when you plugin analyzer USB cable to PC, point the driver for “mchpcdc.inf” file. Find in the zip package for “driver” folders and select this file.


The next is OLS client. It is just a zip package and unzip it to required place to install.


– To start measurement, start OLS client

– At menu bar, select  Capture–> Device –> Openbench LogicSniffer.

– At menu bar, select Capture–> Begincapture

– Select Serial port , my PC port is COM12. Leave port speed : 112500 and device : Openbench Logicsniffer.

– You may need to set Acquisition tab for more utilization. Most interested option are Sampling rate and recording size.

– For sampling rate, you can set the highest “200MHz” if you don’t to brother. For rule of thumb, the sampling rate should be twice of measuring signal. ie: if you want to measure 9600 kbps UART output, sampling rate should be 20kHz at least.

– For Recording size, you can check “Automatic” if you don”t brother. For rule of thumb, OBLS support, 24K samples for 8 inputs channel. If you use 16 channel inputs, it will reduced to 12K proportionally. For 24 inputs, it is 8K and so on.

– It is a good idea to check “Noise Filter” to prevent transition spike.

– My test don’t need trigger and leave it. OLS also supports single  trigger or complex trigger mode. For more detailed, here is tutorials in DP site.




– Then click “Capture” to start  capturing.

And here the result is. All hardware, softwares and OLS, OBLS are working well.


– Both clients work well and the core functions are the same.

– Personally, I prefer OLS client interface more, its interface is cool

– OLS client can be easily created new plugins with just a putting a file. I want to learn more about this function. Can I add new protocol decoding function as simple RC5 or complex LIN? Can some one point me out?

– I have an idea to test 200MHz sampling capability. I will update soon.

Updated :

Testing MPLABX and Open Bench Logic Analyzer (part-1)

I am a long time fan of PIC microcontroller. I used MPLAD IDE since I learned PIC. Now, developers of Microchip prepared a turn point for their IDE and development platform. The MPLABX is a beta stage IDE for past and upcoming microcontroller development. I like the way of AVR (totally free, flexible and open) and seem Microchip also want to turn this way. Some distant features of their partially open source MPLABX ( I mean partially because it is not fully open source,  IDE is open but compiler and libs are still closed 😛 ) are-

  • Used open sourced IDE , NetBean
  • Mostly open source, free software components and plug -ins (Microchip used WinUSB/LibUSB for USB rather than their propitery USB stack)
  • Crossed platform, Support Subversion, CVS, Mercurial, bugzellia and tracker and most opensoure features of NetBean
  • Seem the most useful feature “History”, you can forward/backward your change
  • MPLAB8 and X are don’t brother each. You can install both. There is also a con version tool to change 8 project to X
  • Assembler, compiler are not changed

I got my new Open bench logic analyzer last month from Seedstudio. I am also a fan of DangerousPrototypes. So, I created a project to test both MPLABX and OBLS.

The idea is simple. To create an 8bits signal generator with PIC. The software project is developed by MPLABX and  target hardware is PIC16F628A. I used this PIC because it is cheap and fast (20MHz clock) in low end controllers series.

First I download MPLABX from here. The installer is about 220M. I don’t nee others C30, C32 compiler at the moment. You can download if you want to use them.


I choosethe following along with IDE.

  • PIC18C lite
  • Hitech C lite
  • HitechC pro lite

You may need latest Java.


Installation is straight forward and finished about 15 mins.

After that, installed C18 and HitechC lite version.The are separate installers. You need to download and installed separately.

Then, Hitech C  lites. The installation style of both HitechC lite and pro are the same except you can choosed trial and lite versions in installati

Then, launch MPLABX…

The four panes as usual IDE, project, project , navigator, editor and output. The two bars, menu and editor. There is also error stripe beside editor window.

There is a guide “Getting started with MPLABX” in web site. But this is exampled with high end PIC and C18 compiler. Not with low end PIC and free MPASM assembler.So, I listed my work here.

– Starting a project

Click on the New Project icon on the toolbar, or select File –> New Project from the menu.

– Select Microchip Embedded under Categories and select C/ASM Standalone Project under Projects.
– Click Next.

– Select Device –> Family: All Families  –> Device: PIC16F628A and Next

– You can select header for debug. I don’t need at the moment and skip it by clicking just “Next”

– I want to use PICKit2 and select it. If you have any tools from listed, you can choose. If you dont have any listed device, just choose “Simulator”.

– Select Compiler –> Mpasm, I choosed this I want to write the code in Assembly. If you want to use listed compiler, you can select here.

– Select where do you want to store your project.

– Click Next and project creation is done. There is a project “logictester” in project pane and infos, setting about the project is shown in navigation.

– This is just the beginning. There is no source file in project. I copy the template “16F628ATEMP” from ../MPLABX/MPASM30/templates/code folder to project ../logictester/nbproject  folder.

– Right click “Source” in project windows and select “Add existing Item..” and choose 16F628ATEMP. Click the file name and rename the file as “logictest”. Make sure to choose Store path as: to “Relative”.

– There is a source “logictest” under source “Source Files” in project window. Double click it to open at editor window.

–  Edit the code as follow. I want to develop the code in assembly to get both speed and optimization. The code is quite simple, just an software base 8-bits counter and output to PORTB of PIC. The software counter will increase from zero to 255 (in binary, 00000000~11111111) and loop forever. Each counter value will be output t0 PORTB simultaneously.  Thus, all 8-pins of PORTB generate frequency twice of its’ lower pin. If LSB pin-1 generates 1MHz, most MSB pin-2 will generate 500 KHz and so on.

the rough pseudo code is:


PORTB = 00000000

PORTB = 00000001

PORTB = 00000010

PORTB = 00000011

PORTB = 00000100



PORTB = 11111110

PORTB = 11111111


logic tester source

– Build the circuit and attached with my DIY PICKit2 clone. The circuit is quite simple, a 16F628A, 20MHz crystal, 2x22pf capacitors and +5V power.

– To build project, Click on the Debug Project toolbar button.  Building the code for debugging, programming the target and running the program should done.

– Oops, an error show device ID is wrong. I manually checked with PICkit2 standalone programmer software that PIC and PICkit2 are connected well and the device is surely chosen 628A. I am no idea about this error. So, I just click “yes”.

– The message show that building is complete.

– When done, click on Pause then End Debug Session.

– Then, I tested by click “Program Target” on main tool bar. This can also make and program to target. Not need to click Build or debug. It also show the same error but click “yes” and shows building successful and loading complete.

–  Some issues are,

  • I noticed about MPLABX, PICkit2 support here http://dangerousprototypes.com/2010/11/02/reactions-mplab-x-ide/
  • The connection  with PicKit2 shows also error in debug tool
  • Although errors are shown, the building  project  is done. There is also a hex file “logictester.X.production.HEX” under ../dist/default/production folder.
  • The programming to target is also done. I rechecked manually with PicKit2 standalone program. The hex file is successfully loaded to PIC.
  • Some facts checking at  “MPLABX Beta Limmitations” page on IDE start page
  • At “Device and Compiler” support table, PICkit2 and ICD2 are listed

  • At “MPLAB X IDE Features Surpotted” table, device debug header for ICD2 and Pickit2 are not listed

  • From the current issues, ICD2 is not supported yet.
i. There is no Debug Header support at this time for ICD2.

– Conclusion

  • Pickit2 is supported  but not fully yet (can program the target although it shows error).
  • ICD2 is not supported yet
  • I don’t know why the device ID error is shown. If any one know about this, please point me out.
  • It is a good IDE. I love to use such IDE and functions.
  • Although IDE is open, Microchip don’t open or free to it’s C compiler. Lite versions are very limited. Hopefully they change the way of AVR one day. If not, they will loose new generation of developer, students, researchers (like me) who they cannot earn much money for development tools. So, the reason which I use this IDE is will be when I need to develop in Assembly not in C.

– My project source codes

PIC 16F828A Logic Tester

– Refrences;

Next post, I will post testing with OBLS. Stay tune.