README.txt
This is the README file for the port of NuttX to the NuvoTon NuTiny-SDK-NUC120 board. This board has the NUC120LE3AN chip with a built-in NuLink debugger.
Contents
- Development Environment
- GNU Toolchain Options
- NuttX Buildroot Toolchain
- LEDs
- Serial Console
- Debugging
- NuTiny-specific Configuration Options
- Configurations
Development Environment
Either Linux or Cygwin on 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.
You must have already configured NuttX in
<some-dir>/nuttx.tools/configure.sh nutiny-nuc120:
<sub-dir>Download the latest buildroot package into
<some-dir>unpack the buildroot tarball. The resulting directory may have versioning information on it like buildroot-x.y.z. If so, rename
<some-dir>/buildroot-x.y.z to<some-dir>/buildroot.cd
<some-dir>/buildrootcp boards/cortexm0-eabi-defconfig-4.6.3 .config
make oldconfig
make
Make sure that the PATH variable includes the path to the newly built binaries.
See the file boards/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 NuTiny has a single green LED that can be controlled from software. This LED is connected to PIN17. It is pulled high so a low value will illuminate the LED.
If CONFIG_ARCH_LEDs is defined, then NuttX will control the LED on board the NuTiny. The following definitions describe how NuttX controls the LEDs:
SYMBOL Meaning LED state
Initially all LED is OFF
------------------- ----------------------- ------------- ------------
LED_STARTED NuttX has been started LED ON
LED_HEAPALLOCATE Heap has been allocated LED ON
LED_IRQSENABLED Interrupts enabled LED ON
LED_STACKCREATED Idle stack created LED ON
LED_INIRQ In an interrupt LED should glow
LED_SIGNAL In a signal handler LED might glow
LED_ASSERTION An assertion failed LED ON while handling the assertion
LED_PANIC The system has crashed LED Blinking at 2Hz
LED_IDLE NUC1XX is in sleep mode (Optional, not used)
Serial Console
As with most NuttX configurations, the NuTiny-SKD-NUC120 configurations depend on having a serial console to interact with the software. The NuTiny-SDK-NUC120, however, has not on-board RS-232 drivers so will be necessary to connect the NuTiny-SDK-NUC120 UART pins to an external RS-232 driver board or TTL-to-Serial USB adaptor.
By default UART1 is used as the serial console on these boards. NUC120LE3AN is provided as an LQFP48 package and, for this case, the UART1 RX signal (RXD1) is on PB.4, pin 8, and the TX signal (TXD1) is on PB.5, pin 9. These pins are available on the NuTiny-SDC-NUC120 JP5.
NOTE: The TX vs RX labeling may be confusing. On one RS-232 driver board, I had to connect the NUC120 TXD0 pin to the driver boards RXD pin. How confusing!
UART0 is an alternative that can be selected by modifying the default configuration. UART0 RX (RXD0) is on PB.0, pin 17, and the TX signal (TXD0) is on PB.1, pin 18. These pins are available on the NuTiny-SDC-NUC120 JP1.
NOTE: PB.0, pin 17, is also used to control the user LED on board (labeled "IO"). CONFIG_ARCH_LED should not be selected if UART0 is used.
The NUC120LE3AN does not support UART2.
Debugging
The NuTiny-SDK-NUC120 includes a built-in NuLink debugger. Unfortunately, full debug support is available only with the Keil and IAR toolchains. There is, however, a free program called ICP (In-Circuit Programmer). It can be used to burn programs into FLASH (aka APROM).
The ICP program can also be used to burn an ISP program into LDROM. The ISP (In-System Programmer) is available free from the Nuvton website.
Then NuttX build does not set the configuration words at 0x0030000-0x00300004. You should uncheck the Config box when burning APROM or the previous contents of the configuration words will be erased.
NuTiny-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=nuc1xx
CONFIG_ARCH_CHIP_name - For use in C code to identify the exact
chip:
CONFIG_ARCH_CHIP_NUC120LE3AN=y
CONFIG_ARCH_BOARD - Identifies the boards/ subdirectory and
hence, the board that supports the particular chip or SoC.
CONFIG_ARCH_BOARD=nutiny-nuc120 (for the NuTiny-SDK-NUC120 development board)
CONFIG_ARCH_BOARD_name - For use in C code
CONFIG_ARCH_BOARD_NUTINY_NUC120=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 NUC100/120 line and may not be available for the NUC120LE3AN in particular:
AHB ---
CONFIG_NUC_PDMA Peripheral DMA
CONFIG_NUC_FMC Flash memory
CONFIG_NUC_EBI External bus interface
APB1 ----
CONFIG_NUC_WDT Watchdog timer
CONFIG_NUC_RTC Real time clock (RTC)
CONFIG_NUC_TMR0 Timer0
CONFIG_NUC_TMR1 Timer1
CONFIG_NUC_I2C0 I2C interface
CONFIG_NUC_SPI0 SPI0 master/slave
CONFIG_NUC_SPI1 SPI1 master/slave
CONFIG_NUC_PWM0 PWM0
CONFIG_NUC_PWM1 PWM1
CONFIG_NUC_PWM2 PWM2
CONFIG_NUC_PWM3 PWM3
CONFIG_NUC_UART0 UART0
CONFIG_NUC_USBD USB 2.0 FS device controller
CONFIG_NUC_ACMP Analog comparator
CONFIG_NUC_ADC Analog-digital-converter (ADC)
APB2 ---
CONFIG_NUC_PS2 PS/2 interface
CONFIG_NUC_TIMR2 Timer2
CONFIG_NUC_TIMR3 Timer3
CONFIG_NUC_I2C1 I2C1 interface
CONFIG_NUC_SPI2 SPI2 master/slave
CONFIG_NUC_SPI3 SPI3 master/slave
CONFIG_NUC_PWM4 PWM4
CONFIG_NUC_PWM5 PWM5
CONFIG_NUC_PWM6 PWM6
CONFIG_NUC_PWM7 PWM7
CONFIG_NUC_UART1 UART1
CONFIG_NUC_UART2 UART2
CONFIG_NUC_I2S I2S interface
NUC1XX 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 NuTiny-SDK-NUC120 configuration is maintained in a sub-directory and can be selected as follow:
tools/configure.sh nutiny-nuc120:<subdir>
Where <subdir> is one of the following:
nsh:
Configures the NuttShell (nsh) located at apps/examples/nsh. The Configuration enables the serial interfaces on UART1. 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 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
3. Serial Console. A serial console is necessary to interrupt with
NSH. The serial console is configured on UART1 which is available
on JP5:
UART1 RX signal (RXD1) is on PB.4, pin 8, and
UART1 TX signal (TXD1) is on PB.5, pin 9.
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 implemented 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 memory to support 3 or 4 application
threads in addition to NSH.