README
^^^^^^
This README discusses issues unique to NuttX configurations for the
Freescale DEMO9S12NE64 development board.
CONTENTS
^^^^^^^^
o MC9S12NE64 Features
o Development Environment
o NuttX Buildroot Toolchain
o FreeScale HCS12 Serial Monitor
o Soft Registers
o HCS12/DEMO9S12NEC64-specific Configuration Options
o Configurations
MC9S12NE64 Features
^^^^^^^^^^^^^^^^^^^
o 16-bit HCS12 core
- HCS12 CPU
- Upward compatible with M68HC11 instruction set
- Interrupt stacking and programmer's model identical to M68HC11
- Instruction queue
- Enhanced indexed addressing
- Memory map and interface (MMC)
- Interrupt control (INT)
- Background debug mode (BDM)
- Enhanced debug12 module, including breakpoints and change-of-flow
trace buffer (DBG)
- Multiplexed expansion bus interface (MEBI) - available only in
112-pin package version
o Wakeup interrupt inputs
- Up to 21 port bits available for wakeup interrupt function with
digital filtering
o Memory
- 64K bytes of FLASH EEPROM
- 8K bytes of RAM
o Analog-to-digital converter (ATD)
- One 8-channel module with 10-bit resolution
- External conversion trigger capability
o Timer module (TIM)
- 4-channel timer
- Each channel configurable as either input capture or output
compare
- Simple PWM mode
- Modulo reset of timer counter
- 16-bit pulse accumulator
- External event counting
- Gated time accumulation
o Serial interfaces
- Two asynchronous serial communications interface (SCI)
- One synchronous serial peripheral interface (SPI)
- One inter-IC bus (IIC)
o Ethernet Media access controller (EMAC)
- IEEE 802.3 compliant
- Medium-independent interface (MII)
- Full-duplex and half-duplex modes
- Flow control using pause frames
- MII management function
- Address recognition
- Frames with broadcast address are always accepted or always
rejected
- Exact match for single 48-bit individual (unicast) address
- Hash (64-bit hash) check of group (multicast) addresses
- Promiscuous mode
o Ethertype filter
o Loopback mode
o Two receive and one transmit Ethernet buffer interfaces
o Ethernet 10/100 Mbps transceiver (EPHY)
- IEEE 802.3 compliant
- Digital adaptive equalization
- Half-duplex and full-duplex
- Auto-negotiation next page ability
- Baseline wander (BLW) correction
- 125-MHz clock generator and timing recovery
- Integrated wave-shaping circuitry
- Loopback modes
o CRG (clock and reset generator module)
- Windowed COP watchdog
- Real-time interrupt
- Clock monitor
- Pierce oscillator
- Phase-locked loop clock frequency multiplier
- Limp home mode in absence of external clock
- 25-MHz crystal oscillator reference clock
o Operating frequency
- 50 MHz equivalent to 25 MHz bus speed for single chip
- 32 MHz equivalent to 16 MHz bus speed in expanded bus modes
o Internal 2.5-V regulator
- Supports an input voltage range from 3.3 V ± 5%
- Low-power mode capability
- Includes low-voltage reset (LVR) circuitry
o 80-pin TQFP-EP or 112-pin LQFP package
- Up to 70 I/O pins with 3.3 V input and drive capability (112-pin
package)
- Up to two dedicated 3.3 V input only lines (IRQ, XIRQ)
o Development support
- Single-wire background debug™ mode (BDM)
- On-chip hardware breakpoints
- Enhanced DBG debug features
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.
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 HC12 GCC toolchain (if
different from the default in your PATH variable).
If you have no HC12 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
environments.
1. You must have already configured NuttX in <some-dir>/nuttx.
tools/configure.sh demo9s12nec64:<sub-dir>
2. Download the latest buildroot package into <some-dir>
3. 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.
4. cd <some-dir>/buildroot
5. cp boards/m9s12x-defconfig-3.3.6 .config
6. make oldconfig
7. make
If the make fails because it can't find the file to download, you may
have to locate the file on the internet and download it into the archives/
directory manually. For example, binutils-2.18 can be found here:
http://ftp.gnu.org/gnu/binutils/
8. 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
detailed PLUS some special instructions that you will need to follow if you are
building a Cortex-M3 toolchain for Cygwin under Windows.
FreeScale HCS12 Serial Monitor
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
General:
The NuttX HCS12 port is configured to use the Freescale HCS serial
monitor. This monitor supports primitive debug commands that allow
FLASH/EEPROM programming and debugging through an RS-232 serial
interface. The serial monior is 2Kb in size and resides in FLASH at
addresses 0xf800-0xffff. The monitor does not use any RAM other than
the stack itself.
AN2458
The serial monitor is described in detail in Freescale Application
Note AN2458.pdf.
COP:
The serial monitor uses the COP for the cold reset function and should
not be used by the application without some precautions (see AN2458).
Clocking:
The serial monitor sets the operating frequency to 24 MHz. This is
not altered by the NuttX start-up; doing so would interfere with the
operation of the serial monitor.
Memory Configuration:
Registers:
o Register space is located at 0x0000-0x03ff.
FLASH:
o FLASH memory is any address greater than 0x4000. All paged
addresses are assumed to be FLASH memory.
o Application code should exclude the 0xf780-0xff7f memory.
SRAM:
o RAM ends at 0x3FFF and builds down to the limit of the device's
available RAM.
o The serial monitor's stack pointer is set to the end of RAM+1
(0x4000).
EEPROM:
o EEPROM (if the target device has any) is limited to the available
space between the registers and the RAM (0x0400 to start of RAM).
External Devices:
o External devices attached to the multiplexed external bus
interface are not supported
Serial Communications:
The serial monitor uses RS-232 serial communications through SCI0 at
115,200 baud. The monitor must have exclusive use of this interface.
Access to the serial port is available through a monitor jump table.
Interrupts:
The serial monitor redirects interrupt vectors to an unprotected
portion of FLASH just before the protected monitor program
(0xf780-0xf7fe). The monitor will automatically redirect vector
programming operations to these user vectors. The user code should
therefore keep the normal (non-monitor) vector locations
(0xff80-0xfffe).
Soft Registers
^^^^^^^^^^^^^^
The mc68hcs12 compilation is prone to errors like the following:
CC: lib_b16sin.c
lib_b16sin.c: In function `b16sin':
lib_b16sin.c:110: error: unable to find a register to spill in class `S_REGS'
lib_b16sin.c:110: error: this is the insn:
(insn:HI 41 46 44 8 (parallel [
(set (subreg:SI (reg:DI 58 [ rad ]) 4)
(reg/v:SI 54 [ rad ]))
(clobber (scratch:HI))
]) 20 {movsi_internal} (insn_list 46 (nil))
(expr_list:REG_UNUSED (scratch:HI)
(expr_list:REG_NO_CONFLICT (reg/v:SI 54 [ rad ])
(nil))))
lib_b16sin.c:110: confused by earlier errors, bailing out
There are several ways that this error could be fixed:
1. Increase the number of soft registers (i.e., "fake" registers defined
at fixed memory locations). This can be done by adding something like
-msoft-reg-count=4 to the CFLAGS. This approach was not taken
because:
- This slows hcs12 performance
- All of these soft registers wouil have to be saved and restored
on every interrupt and context switch.
2. Lowering the optimization level by dropping -Os to -O2 or, more likely,
by removing -fomit-frame-pointer. Also not desirable becauase 99% of the
files that do not have this problem also increase in size. Special case
compilation with reduced optimization levels just for the files that need
it could be done, but this would complicate the make system.
3. Restructuring files to reduce the complexity. If you add local variables
to hold intermediate computational results, this error can be eliminated.
This is the approach taken in NuttX. It has disadvantages only in that
(1) it takes some effort and good guessing to eliminate the problem, and (2)
the problem is not really eliminated -- it can and will re-occur when files
are changed or new files are added.
4. Many files are built that are needed by DEM09S12NE64. Another very simple
option if those problem files are needed is to just remove the offending
files from the Make.defs file so that they no longer cause a problem.
HCS12/DEMO9S12NEC64-specific Configuration Options
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
CONFIG_ARCH - Identifies the arch/ subdirectory. This should
be set to:
CONFIG_ARCH=hc
CONFIG_ARCH_family - For use in C code:
CONFIG_ARCH_HC=y
CONFIG_ARCH_architecture - For use in C code:
CONFIG_ARCH_HCS12=y
CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory
CONFIG_ARCH_CHIP=mc92s12nec64
CONFIG_ARCH_CHIP_name - For use in C code
CONFIG_ARCH_CHIP_MCS92S12NEC64
CONFIG_ARCH_BOARD - Identifies the boards/ subdirectory and
hence, the board that supports the particular chip or SoC.
CONFIG_ARCH_BOARD=demo9s12nec64
CONFIG_ARCH_BOARD_name - For use in C code
CONFIG_ARCH_BOARD_DEMOS92S12NEC64 (for the Freescale DEMO9S12NE64 development board)
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 RAM.
CONFIG_RAM_START - The start address of installed RAM
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
GPIO Interrupts
CONFIG_HCS12_GPIOIRQ - Enable general support for GPIO IRQs
CONFIG_HCS12_PORTG_INTS - Enable PortG IRQs
CONFIG_HCS12_PORTH_INTS - Enable PortH IRQs
CONFIG_HCS12_PORTJ_INTS - Enable PortJ IRQs
HCS12 build options:
CONFIG_HCS12_SERIALMON - Indicates that the target systems uses
the Freescale serial bootloader.
CONFIG_HCS12_NONBANKED - Indicates that the target systems does not
support banking. Only short calls are made; one fixed page is
presented in the paging window. Only 48Kb of FLASH is usable
in this configuration: pages 3e, 3d, then 3f will appear as a
contiguous address space in memory.
HCS12 Sub-system support
CONFIG_HCS12_SCI0
CONFIG_HCS12_SCI1
HCS12 specific device driver settings:
CONFIG_SCIn_SERIAL_CONSOLE - selects SCIn for the console and ttys0
(default is the SCI0).
CONFIG_SCIn_RXBUFSIZE - Characters are buffered as received.
This specific the size of the receive buffer
CONFIG_SCIn_TXBUFSIZE - Characters are buffered before
being sent. This specific the size of the transmit buffer
CONFIG_SCIn_BAUD - The configure BAUD of the UART.
CONFIG_SCIn_BITS - The number of bits. Must be either 7 or 8.
CONFIG_SCIn_PARTIY - 0=no parity, 1=odd parity, 2=even parity, 3=mark 1, 4=space 0
CONFIG_SCIn_2STOP - Two stop bits
Configurations
^^^^^^^^^^^^^^
Common Configuration Notes
--------------------------
1. Each Freescale HCS12 configuration is maintained in a sub-directory and
can be selected as follow:
tools/configure.sh demo9s12nec64:<subdir>
Where <subdir> is one of the configuration sub-directories described in
the following paragraph.
2. These configurations use the mconf-based configuration tool. To
change a 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.
3. By default, all configurations assume that you are building under
Linux (should work under Windows with Cygwin as well). This is
easily reconfigured:
CONFIG_HOST_LINUX=y
Configuration Sub-Directories
-----------------------------
ostest
This configuration directory, performs a simple OS test using
examples/ostest.
