General Android Peripheral (KL25Z) tested

Last year I started to develop a General Android Peripheral platform with Freescale's first Kinetis L micro MKL25Z128VLK4.  When I present it on Design Shanghai 2013, its hardware is under development, which you can reveal on above picture.

It was inspirited from IOIO design and ADK for its ADB/ADK/AOA conception. However, since MKL25Z is quite different from Microchip and Atmel's micro, I developed the code on FSL's USB stack, and reference some code from Arduino UHS (USB host shield).

As a software engineer, the roadblock for this project is hardware design and assembly. 

The code runs well on FRDM-KL25Z with my custom host port. (Yep, I modified the port hardware to enable its host feature on board.) However, I can not solder the samples since 0.5mm pitch QFP80 is difficult to me.

I got them soldered with my friends, but all of these boards can not be accessed by any of my debuggers. And I found 125 KHz output from its reset pin. Check these two links for details.

After visiting Freescale Shanghai office and digging with search engine, I found a solution, which adding an extra series resistor to SWD_CLK pin. Now, three boards are working now. 

Here comes the Star for this blog!

Looks ugly? Yes, it is manually soldered by my friend (for MCU) and me (for rest).

However, I have to revise my hardware, since they are not good enough for public and hobbyists. I wrote this because I want someone who might be interested to know its planned features.

Features Planned
  • ADB (USB host on MCU, available now for firmware and demo)
  • ADK (USB host on MCU, not available)
  • CDC (USB host on Android, firmware done, host driver in development)
  • CDC (USB host on Android, via CP2102, as same as my LPC812MiniKit)
  • Audio Jack (ADC/DAC/GPIO on MCU for FSK modem)
  • Bluetooth 2.0 module (tested on LPC812MiniKit)

Feedbacks are welcome
Although I wrote blog via email, you can still reach me by email. ( It is painful to be isolated from my friends worldwide.

You can support my development by visiting my web shop on

Up to now only LPC812MiniKit is available, which is also Android oriented design. I will put more items on, including GAP (KL25Z) and open source debugger SDA+ as soon as I get back the hardware.

All items are open source. 


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