README
This is a README file for the port of NuttX to the Teensy-3.1 from PJRC (https://www.pjrc.com/). The Teensy-3.1 features the Freescale MK20DX256VLH7 chip (now NXP). The MK20DX256VLH7 is a 64-pin Cortex-M4 running at 72MHz. It has 256KiB of program FLASH memory and 64KiB of SRAM. For more information about the Teensy 3.1, see
https://www.pjrc.com/teensy/teensy31.html
https://www.pjrc.com/store/teensy31.html
This board configuration can also be used with the older Teensy-3.0. The Teensy-3.0 has the same schematic (although some pins are not used on the Teensy-3.0). The primary difference is that the Teensy 3.0 has a MK20DX128VLH5 with slightly less capability. There are many difference between the MK20DX256VLH7 and the MK20DX128VLH5 but the basic differences that effect how you configure NuttX are:
--------------- -------------- -------------- ---------------------------
Feature Teensy 3.0 Teensy 3.1 Teensy 3.0 CONFIGURATION
--------------- -------------- -------------- ---------------------------
Processor
Core MK20DX128VLH5 MK20DX256VLH7 CONFIG_ARCH_CHIP_MK20DX128VLH5=y
Rated Speed 48 MHz 72 MHz See Note 1
Overclockable 96 MHz 96 MHz CONFIG_TEENSY_3X_OVERCLOCK=y
Flash Memory 128 KB 256 KB See Note 1
SRAM 16 KB 64 KB CONFIG_RAM_SIZE=16384 and
see Note 2
--------------- -------------- -------------- ---------------------------
NOTES: 1. Settings in boards/arm/kinetis/teensy-3.x/include/board.h will automatically select the correct clocking based on CONFIG_ARCH_CHIP_MK20DX128VLH5=y. 2. The linker script at boards/arm/kinetis/teensy-3.x/scripts/mk30dx128vlh5.ld will automatically be selected when CONFIG_ARCH_CHIP_MK20DX128VLH5=y. It will use the correct FLASH and SRAM sizes.
The initial Teensy-3.1 port is largely the effort of Jakob Odersky. https://github.com/jodersky/nuttx/tree/teensy31-7.6 and https://github.com/jodersky/px4-nuttx
Contents
o STATUS o Pin Configuration o Serial Console o LEDs o Using the Halfkey Loader o Debugging o Teensy-3.1 Configuration settings o Configurations
STATUS
2015-06-11: After some extended tinkering with the PLL setup, the Teensy-3.1 is fully functional using the basic NSH configuration. 2015-06-12: Fix LED (need high drive strength). Calibrate delay loop.
Pin Configuration
Nearly all pins are available to the user. The few port pins used on board are listed below:
----- --------------------------------------
P0RT BOARD USAGE
----- --------------------------------------
PTA0 MINI54TAN / Bootloader
PTA1 MINI54TAN / Bootloader
PTA2 MINI54TAN / Bootloader
PTA3 MINI54TAN / Bootloader
PTA18 16MHz XTAL (XTAL32 is not populated).
PTA19 16MHz XTAL
PTB1 MINI54TAN / Bootloader
PTB2 MINI54TAN / Bootloader
PTC5 LED
----- --------------------------------------
Serial Console
The K20 has three UARTs with pin availability as follows:
--------- ------ ----------- -------------------------
UART PORT BOARD PJRC PINOUT DESCRIPTION
FUNCTION LABEL
--------- ------ ----------- -------------------------
UART0_RX PTA1 (See above) MINI54TAN / Bootloader
PTB16 Pin 0 RX1 / Touch
PTD6 Pin 21 / A7 RX1 / CS / PWM
UART0_TX PTA2 (See above) MINI54TAN / Bootloader
PTB17 Pin 1 TX1 / Touch
PTD7 Pin 5 TX1 / PWM
--------- ------ ----------- -------------------------
UART1_RX PTC3 Pin 9 RX2 / CS / PWM
PTE1 Pad 26 (Pad on back of board)
UART1_TX PTC4 Pin 10 TX2 / CS / PWM
PTE0 Pad 31 (Pad on back of board)
--------- ------ ----------- -------------------------
UART2_RX PTD2 Pin 7 RX3 / DOUT
UART2_TX PTD3 Pin 8 TX3 / DIN
--------- ------ ----------- -------------------------
The default serial console is UART0 on pins 0 (RX) and 1 (TX).
LEDs
A single LED is available driven by PTC5. The LED is grounded so bringing PTC5 high will illuminate the LED.
When CONFIG_ARCH_LEDS is defined in the NuttX configuration, NuttX will control the LED as follows:
SYMBOL Meaning LED
------------------- ----------------------- ------
LED_STARTED NuttX has been started OFF
LED_HEAPALLOCATE Heap has been allocated OFF
LED_IRQSENABLED Interrupts enabled OFF
LED_STACKCREATED Idle stack created ON
LED_INIRQ In an interrupt N/C
LED_SIGNAL In a signal handler N/C
LED_ASSERTION An assertion failed N/C
LED_PANIC The system has crashed FLASH
Thus is LED is statically on, NuttX has successfully booted and is, apparently, running normally. If LED is flashing at approximately 2Hz, then a fatal error has been detected and the system has halted.
Using the Halfkey Loader
See https://www.pjrc.com/teensy/first\_use.htmlhttps://www.pjrc.com/teensy/loader\_cli.html
Debugging
And, at this point, I don't know how to debug the board. There is no way to connect a JTAG SWD debugger, at least not without cutting leads to the MINI54TAN device:
See: http://mcuoneclipse.com/2014/08/09/hacking-the-teensy-v3-1-for-swd-debugging/
Teensy-3.1 Configuration settings
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_CORTEXM4=y
CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory
CONFIG_ARCH_CHIP="kinetis"
CONFIG_ARCH_CHIP_name - For use in C code to identify the exact
chip:
CONFIG_ARCH_CHIP_MK20DX256VLH7=y
CONFIG_ARCH_BOARD - Identifies the boards/ subdirectory and
hence, the board that supports the particular chip or SoC.
CONFIG_ARCH_BOARD="teensy-3.x"
CONFIG_ARCH_BOARD_name - For use in C code
CONFIG_ARCH_BOARD_TEENSY_3X=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=0x00008000 (32Kb)
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
Individual subsystems can be enabled:
To be provided
Configurations
Common Configuration Information
Each Teensy-3.x configurations are maintained in sub-directories and can be selected as follow:
tools/configure.sh teensy-3.x:<subdir>
make oldconfig
Before building, make sure that your PATH environment variable includes the correct path to the directory than holds your toolchain binaries.
If this is a Windows native build, then configure.bat should be used instead of configure.sh:
configure.bat teensy-3.x\<subdir>
And then build NuttX by simply typing the following. At the conclusion of the make, the nuttx binary will reside in an ELF file called, simply, nuttx.
make oldconfig
make
The <subdir> that is provided above as an argument to the tools/configure.sh must be is one of the directories listed below.
NOTES:
- These configurations use the mconf-based configuration tool. To change any of these configurations 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.
Unless stated otherwise, all configurations generate console output on [To be provided].
All of these configurations are set up to build under Windows using the "GNU Tools for ARM Embedded Processors" that is maintained by ARM (unless stated otherwise in the description of the configuration).
https://developer.arm.com/open-source/gnu-toolchain/gnu-rm
That toolchain selection can easily be reconfigured using 'make menuconfig'. Here are the relevant current settings:
Build Setup: CONFIG_HOST_WINDOWS=y : Window environment CONFIG_WINDOWS_CYGWIN=y : Cywin under Windows
System Type -> Toolchain: CONFIG_ARM_TOOLCHAIN_GNU_EABI=y : GNU ARM EABI toolchain
NOTE: As of this writing, there are issues with using this tool at the -Os level of optimization. This has not been proven to be a compiler issue (as least not one that might not be fixed with a well placed volatile qualifier). However, in any event, it is recommend that you use not more that -O2 optimization.
Configuration sub-directories -----------------------------
nsh:
Configures the NuttShell (nsh) located at apps/examples/nsh.
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 ARM EABI 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_ARM_TOOLCHAIN_GNU_EABI=y : GNU EABI toolchain for Windows
Support for builtin applications is enabled, but in the base configuration no builtin applications are selected (see NOTES below).