KL27Z128/256 board
==================
2016/11/30

KL27Z is configured to use internal 48MHz RC oscillator.

The board has push button on PTA4 and LED on PTD7. The button works as 'a' key and the LED as an indicator for capslock.


Resources
---------
### Kinetis KL2x
http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/kinetis-cortex-m-mcus/l-series-ultra-low-power-m0-plus/kinetis-kl2x-48-mhz-usb-ultra-low-power-microcontrollers-based-on-arm-cortex-m0-plus:KL2x

### KL27Z128/256 Data Sheet
http://www.nxp.com/assets/documents/data/en/data-sheets/KL27P64M48SF6.pdf

### KL27Z128/256 Reference Manual
http://www.nxp.com/assets/documents/data/en/reference-manuals/KL27P64M48SF6RM.pdf

### Errata
http://www.nxp.com/assets/documents/data/en/errata/KINETIS_L_1N71K.pdf

>>
e9457: Kinetis Flashloader/ ROM Bootloader: The peripheral auto-detect code in
bootloader can falsely detect presence of SPI host causing non-responsive
bootloader
Description: During the active peripheral detection process, the bootloader can interpret spurious data on
the SPI peripheral as valid data. The spurious data causes the bootloader to shutdown all
peripherals except the “falsely detected" SPI and enter the command phase loop using the
SPI. After the bootloader enters the command phase loop using the SPI, the other peripherals
are ignored, so the desired peripheral is no longer active.
The bootloader will not falsely detect activity on the I2C, UART, or USB interfaces, so only the
SPI interface is affected.
Workaround: Ensure that there is an external pull-up on the SPI chip-select pin or that the pin is driven high.
This will prevent the bootloader from seeing spurious data due to activity on the SPI clock pin.

### Kinetis Bootloader and blhost
http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/kinetis-cortex-m-mcus/kinetis-symbols-footprints-and-models/kinetis-bootloader:KBOOT


Build
-----

    make


Program
-------
Flash firmware with ROM bootloader.

    blhost -u -- flash-image  build/kl27z.hex erase


TODO
----
- Fix boards/ELF files
- add macro `USBx_CTL_RESUME` to ChibiOS-Contrib/os/common/ext/CMSIS/KINETIS/kl27zxxx.h