README.txt
==========

This is the README file for the port of NuttX to the Freescale Freedom KL25Z
board. This board has the MKL25Z128 chip with a built-in SDA debugger.

Contents
========

- Development Environment
- GNU Toolchain Options
- NuttX Buildroot Toolchain
- LEDs
- Serial Console
- mbed
- Freedom KL25Z-specific Configuration Options
- Configurations

Development Environment
=======================

Either Linux or Cygwin under Windows can be used for the development environment.
The source has been built only using the GNU toolchain (see below). Other
toolchains will likely cause problems.

GNU Toolchain Options
=====================

As of this writing, all testing has been performed using the NuttX buildroot
toolchain described below. I have also verified the build using the
CodeSourcery GCC toolchain for windows. Most any contemporary EABI GCC
toolchain should work will a little tinkering.

NuttX Buildroot Toolchain
=========================

A GNU GCC-based toolchain is assumed. The PATH environment variable should
be modified to point to the correct path to the Cortex-M0 GCC toolchain (if
different from the default in your PATH variable).

If you have no Cortex-M0 toolchain, one can be downloaded from the NuttX
Bitbucket download site (https://bitbucket.org/nuttx/buildroot/downloads/).
This GNU toolchain builds and executes in the Linux or Cygwin environment.

1. You must have already configured Nuttx in /nuttx.

tools/configure.sh freedom-kl25z/

2. Download the latest buildroot package into

3. unpack the buildroot tarball. The resulting directory may
have versioning information on it like buildroot-x.y.z. If so,
rename /buildroot-x.y.z to /buildroot.

4. cd /buildroot

5. cp configs/cortexm0-eabi-defconfig-4.6.3 .config

6. make oldconfig

7. make

8. Make sure that the PATH variable includes the path to the newly built
binaries.

See the file configs/README.txt in the buildroot source tree. That has more
details PLUS some special instructions that you will need to follow if you are
building a Cortex-M0 toolchain for Cygwin under Windows.

LEDs
====

The Freedom KL25Z has a single RGB LED driven by the KL25Z as follows:

------------- --------
RGB LED KL25Z128
------------- --------
Red Cathode PTB18
Green Cathode PTB19
Blue Cathode PTD1

NOTE: PTD1 is also connected to the I/O header on J2 pin 10 (also known as D13).

If CONFIG_ARCH_LEDs is defined, then NuttX will control the LED on board the
Freedom KL25Z. The following definitions describe how NuttX controls the LEDs:

SYMBOL Meaning LED state
Initially all LED is OFF
------------------- ----------------------- --------------------------
LED_STARTED NuttX has been started R=OFF G=OFF B=OFF
LED_HEAPALLOCATE Heap has been allocated (no change)
LED_IRQSENABLED Interrupts enabled (no change)
LED_STACKCREATED Idle stack created R=OFF G=OFF B=ON
LED_INIRQ In an interrupt (no change)
LED_SIGNAL In a signal handler (no change)
LED_ASSERTION An assertion failed (no change)
LED_PANIC The system has crashed R=FLASHING G=OFF B=OFF
LED_IDLE K25Z1XX is in sleep mode (Optional, not used)

Serial Console
==============

As with most NuttX configurations, the Freedom KL25Z configurations
depend on having a serial console to interact with the software. The
Freedom KL25Z, however, has no on-board RS-232 drivers so will be
necessary to connect the Freedom KL25Z UART pins to an external
RS-232 driver board or TTL-to-Serial USB adaptor.

By default UART0 is used as the serial console on this boards. The UART0
is configured to work with the OpenSDA USB CDC/ACM port:

------ ------------------------------- -----------------------------
PIN PIN FUNCTIONS BOARD SIGNALS
------ ------------------------------- -----------------------------
Pin 27 PTA1/TSI0_CH2/UART0_RX/FTM2_CH0 UART1_RX_TGTMCU and D0 (PTA1)
Pin 28 PTA2/TSI0_CH3/UART0_TX/FTM2_CH1 UART1_TX_TGTMCU and D1 (PTA2)

But the UART0 Tx/Rx signals are also available on J1:

---------------- ---------
UART0 SIGNAL J1 pin
---------------- ---------
UART0_RX (PTA1) J1, pin 2
UART0_TX (PTA2) J1, pin 4

Ground is available on J2 pin 14. 3.3V is available on J3 and J4.

mbed
====

The Freedom KL25Z includes a built-in SDA debugger. An alternative
to the SDA bootloader is this boot loader from mbed:

http://mbed.org/handbook/mbed-FRDM-KL25Z-Getting-Started
http://mbed.org/handbook/Firmware-FRDM-KL25Z

Using the mbed loader:

1. Connect the KL25Z to the host PC using the USB connector labeled
SDA.
2. A new file system will appear called MBED; open it with Windows
Explorer (assuming that you are using Windows).
3. Drag and drop nuttx.bin into the MBED window. This will load the
nuttx.bin binary into the KL25Z. The MBED window will close
then re-open and the KL25Z will be running the new code.

Using the Freescale SDA debugger is essentially the same. That
debugger will also accept .hex file.

Freedom KL25Z-specific Configuration Options
============================================

CONFIG_ARCH - Identifies the arch/ subdirectory. This should
be set to:

CONFIG_ARCH=arm

CONFIG_ARCH_family - For use in C code:

CONFIG_ARCH_ARM=y

CONFIG_ARCH_architecture - For use in C code:

CONFIG_ARCH_CORTEXM0=y

CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory

CONFIG_ARCH_CHIP=kl

CONFIG_ARCH_CHIP_name - For use in C code to identify the exact
chip:

CONFIG_ARCH_CHIP_MKL25Z128=y

CONFIG_ARCH_BOARD - Identifies the configs subdirectory and
hence, the board that supports the particular chip or SoC.

CONFIG_ARCH_BOARD=freedom-kl25z (for the Freescale FRDM-KL25Z development board)

CONFIG_ARCH_BOARD_name - For use in C code

CONFIG_ARCH_BOARD_FREEDOM_K25Z128=y

CONFIG_ARCH_LOOPSPERMSEC - Must be calibrated for correct operation
of delay loops

CONFIG_ENDIAN_BIG - define if big endian (default is little
endian)

CONFIG_RAM_SIZE - Describes the installed DRAM (SRAM in this case):

CONFIG_RAM_SIZE=16384 (16Kb)

CONFIG_RAM_START - The start address of installed DRAM

CONFIG_RAM_START=0x20000000

CONFIG_ARCH_LEDS - Use LEDs to show state. Unique to boards that
have LEDs

CONFIG_ARCH_INTERRUPTSTACK - This architecture supports an interrupt
stack. If defined, this symbol is the size of the interrupt
stack in bytes. If not defined, the user task stacks will be
used during interrupt handling.

CONFIG_ARCH_STACKDUMP - Do stack dumps after assertions

CONFIG_ARCH_LEDS - Use LEDs to show state. Unique to board architecture.

Individual subsystems can be enabled as follows. These settings are for
all of the K25Z100/120 line and may not be available for the MKL25Z128
in particular:

AHB
---

CONFIG_KL_PDMA Peripheral DMA
CONFIG_KL_FMC Flash memory
CONFIG_KL_EBI External bus interface

APB1
----

CONFIG_KL_WDT Watchdog timer
CONFIG_KL_RTC Real time clock (RTC)
CONFIG_KL_TMR0 Timer0
CONFIG_KL_TMR1 Timer1
CONFIG_KL_I2C0 I2C interface
CONFIG_KL_SPI0 SPI0 master/slave
CONFIG_KL_SPI1 SPI1 master/slave
CONFIG_KL_PWM0 PWM0
CONFIG_KL_PWM1 PWM1
CONFIG_KL_PWM2 PWM2
CONFIG_KL_PWM3 PWM3
CONFIG_KL_UART0 UART0
CONFIG_KL_USBD USB 2.0 FS device controller
CONFIG_KL_ACMP Analog comparator
CONFIG_KL_ADC Analog-digital-converter (ADC)

APB2
---

CONFIG_KL_PS2 PS/2 interface
CONFIG_KL_TIMR2 Timer2
CONFIG_KL_TIMR3 Timer3
CONFIG_KL_I2C1 I2C1 interface
CONFIG_KL_SPI2 SPI2 master/slave
CONFIG_KL_SPI3 SPI3 master/slave
CONFIG_KL_PWM4 PWM4
CONFIG_KL_PWM5 PWM5
CONFIG_KL_PWM6 PWM6
CONFIG_KL_PWM7 PWM7
CONFIG_KL_UART1 UART1
CONFIG_KL_UART2 UART2
CONFIG_KL_I2S I2S interface

K25Z1XX specific device driver settings

CONFIG_UARTn_SERIAL_CONSOLE - Selects the UARTn (n=0,1,2) for the
console and ttys0.
CONFIG_UARTn_RXBUFSIZE - Characters are buffered as received.
This specific the size of the receive buffer for UARTn.
CONFIG_UARTn_TXBUFSIZE - Characters are buffered before
being sent. This specific the size of the transmit buffer
for UARTn.
CONFIG_UARTn_BAUD - The configure BAUD of UARTn,
CONFIG_UARTn_BITS - The number of bits. Must be 5, 6, 7, or 8.
CONFIG_UARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity
CONFIG_UARTn_2STOP - Two stop bits

Configurations
==============

Each FREEDOM-KL25Z configuration is maintained in a sub-directory and
can be selected as follow:

tools/configure.sh freedom-kl25z/

If this is a Windows native build, then configure.bat should be used
instead of configure.sh:

configure.bat freedom-kl25z\

Where is one of the following:

nsh:
---
Configures the NuttShell (nsh) located at apps/examples/nsh. The
Configuration enables the serial interface on UART0. Support for
builtin applications is disabled.

NOTES:

1. This configuration uses the mconf-based configuration tool. To
change this configuration using that tool, you should:

a. Build and install the kconfig-mconf tool. See nuttx/README.txt
see additional README.txt files in the NuttX tools repository.

b. Execute 'make menuconfig' in nuttx/ in order to start the
reconfiguration process.

2. By default, this configuration uses the CodeSourcery toolchain
for Windows and builds under Cygwin (or probably MSYS). That
can easily be reconfigured, of course.

CONFIG_HOST_WINDOWS=y : Builds under Windows
CONFIG_WINDOWS_CYGWIN=y : Using Cygwin
CONFIG_ARMV7M_TOOLCHAIN_CODESOURCERYW=y : CodeSourcery for Windows

3. Serial Console. A serial console is necessary to interrupt with
NSH. The serial console is configured on UART0 which is available
on J1:

---------------- ---------
UART0 SIGNAL J1 pin
---------------- ---------
UART0_RX (PTA1) J1, pin 2
UART0_TX (PTA2) J1, pin 4

Ground is available on J2 pin 14. 3.3V is available on J3 and J4.

It is possible to configure NSH to use a USB serial console instead
of an RS-232 serial console. However, that configuration has not
been impelmented as of this writing.

4. Memory Usage. The size command gives us the static memory usage.
This is what I get:

$ size nuttx
text data bss dec hex filename
35037 106 1092 36235 8d8b nuttx

And we can get the runtime memory usage from the NSH free command:

NuttShell (NSH) NuttX-6.25
nsh> free
total used free largest
Mem: 14160 3944 10216 10216
nsh>

Summary:

- This slightly tuned NSH example uses 34.2KB of FLASH leaving 93.8KB
of FLASH (72%) free from additional application development.

I did not do all of the arithmetic, but it appears to me that of this
34+KB of FLASH usage, probably 20-30% of the FLASH is used by libgcc!
libgcc has gotten very fat!

- Static SRAM usage is about 1.2KB (<4%).

- At run time, 10.0KB of SRAM (62%) is still available for additional
applications. Most of the memory used at runtime is allocated I/O
buffers and the stack for the NSH main thread (1.5KB).

There is probably enough free memroy to support 3 or 4 application
threads in addition to NSH.

5. This configurations has support for NSH built-in applications. However,
in the default configuration no built-in applications are enabled.