README ====== This README discusses issues unique to NuttX configurations for the STM32 Tiny development board. This board is available from several vendors on the net, and may be sold under different names. It is based on a STM32 F103C8T6 MCU, and is (always ?) bundled with a nRF24L01 wireless communication module. Contents ======== - Development Environment - GNU Toolchain Options - IDEs - NuttX EABI "buildroot" Toolchain - NuttX OABI "buildroot" Toolchain - NXFLAT Toolchain - LEDs - PWM - UARTs - Timer Inputs/Outputs - STM32 Tiny -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 ===================== Toolchain Configurations ------------------------ The NuttX make system has been modified to support the following different toolchain options. 1. The CodeSourcery GNU toolchain, 2. The Atollic Toolchain, 3. The devkitARM GNU toolchain, 4. Raisonance GNU toolchain, or 5. The NuttX buildroot Toolchain (see below). All testing has been conducted using the CodeSourcery toolchain for Windows. To use the Atollic, devkitARM, Raisonance GNU, or NuttX buildroot toolchain, you simply need to add one of the following configuration options to your .config (or defconfig) file: CONFIG_ARMV7M_TOOLCHAIN_CODESOURCERYW=y : CodeSourcery under Windows CONFIG_ARMV7M_TOOLCHAIN_CODESOURCERYL=y : CodeSourcery under Linux CONFIG_ARMV7M_TOOLCHAIN_ATOLLIC=y : The Atollic toolchain under Windows CONFIG_ARMV7M_TOOLCHAIN_DEVKITARM=y : devkitARM under Windows CONFIG_ARMV7M_TOOLCHAIN_RAISONANCE=y : Raisonance RIDE7 under Windows CONFIG_ARMV7M_TOOLCHAIN_BUILDROOT=y : NuttX buildroot under Linux or Cygwin (default) If you change the default toolchain, then you may also have to modify the PATH in the setenv.h file if your make cannot find the tools. NOTE: the CodeSourcery (for Windows), Atollic, devkitARM, and Raisonance toolchains are Windows native toolchains. The CodeSourcey (for Linux) and NuttX buildroot toolchains are Cygwin and/or Linux native toolchains. There are several limitations to using a Windows based toolchain in a Cygwin environment. The three biggest are: 1. The Windows toolchain cannot follow Cygwin paths. Path conversions are performed automatically in the Cygwin makefiles using the 'cygpath' utility but you might easily find some new path problems. If so, check out 'cygpath -w' 2. Windows toolchains cannot follow Cygwin symbolic links. Many symbolic links are used in Nuttx (e.g., include/arch). The make system works around these problems for the Windows tools by copying directories instead of linking them. But this can also cause some confusion for you: For example, you may edit a file in a "linked" directory and find that your changes had no effect. That is because you are building the copy of the file in the "fake" symbolic directory. If you use a Windows toolchain, you should get in the habit of making like this: make clean_context all An alias in your .bashrc file might make that less painful. The CodeSourcery Toolchain (2009q1) ----------------------------------- The CodeSourcery toolchain (2009q1) does not work with default optimization level of -Os (See Make.defs). It will work with -O0, -O1, or -O2, but not with -Os. The Atollic "Pro" and "Lite" Toolchain -------------------------------------- One problem that I had with the Atollic toolchains is that the provide a gcc.exe and g++.exe in the same bin/ file as their ARM binaries. If the Atollic bin/ path appears in your PATH variable before /usr/bin, then you will get the wrong gcc when you try to build host executables. This will cause to strange, uninterpretable errors build some host binaries in tools/ when you first make. Also, the Atollic toolchains are the only toolchains that have built-in support for the FPU in these configurations. If you plan to use the Cortex-M4 FPU, you will need to use the Atollic toolchain for now. See the FPU section below for more information. The Atollic "Lite" Toolchain ---------------------------- The free, "Lite" version of the Atollic toolchain does not support C++ nor does it support ar, nm, objdump, or objdcopy. If you use the Atollic "Lite" toolchain, you will have to set: CONFIG_HAVE_CXX=n In order to compile successfully. Otherwise, you will get errors like: "C++ Compiler only available in TrueSTUDIO Professional" The make may then fail in some of the post link processing because of some of the other missing tools. The Make.defs file replaces the ar and nm with the default system x86 tool versions and these seem to work okay. Disable all of the following to avoid using objcopy: CONFIG_RRLOAD_BINARY=n CONFIG_INTELHEX_BINARY=n CONFIG_MOTOROLA_SREC=n CONFIG_RAW_BINARY=n devkitARM --------- The devkitARM toolchain includes a version of MSYS make. Make sure that the the paths to Cygwin's /bin and /usr/bin directories appear BEFORE the devkitARM path or will get the wrong version of make. IDEs ==== NuttX is built using command-line make. It can be used with an IDE, but some effort will be required to create the project. Makefile Build -------------- Under Eclipse, it is pretty easy to set up an "empty makefile project" and simply use the NuttX makefile to build the system. That is almost for free under Linux. Under Windows, you will need to set up the "Cygwin GCC" empty makefile project in order to work with Windows (Google for "Eclipse Cygwin" - there is a lot of help on the internet). Native Build ------------ Here are a few tips before you start that effort: 1) Select the toolchain that you will be using in your .config file 2) Start the NuttX build at least one time from the Cygwin command line before trying to create your project. This is necessary to create certain auto-generated files and directories that will be needed. 3) Set up include pathes: You will need include/, arch/arm/src/stm32, arch/arm/src/common, arch/arm/src/armv7-m, and sched/. 4) All assembly files need to have the definition option -D __ASSEMBLY__ on the command line. Startup files will probably cause you some headaches. The NuttX startup file is arch/arm/src/stm32/stm32_vectors.S. With RIDE, I have to build NuttX one time from the Cygwin command line in order to obtain the pre-built startup object needed by RIDE. NuttX EABI "buildroot" Toolchain ================================ A GNU GCC-based toolchain is assumed. The files */setenv.sh should be modified to point to the correct path to the Cortex-M3 GCC toolchain (if different from the default in your PATH variable). If you have no Cortex-M3 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. cd tools ./configure.sh stm32_tiny/ 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/cortexm3-eabi-defconfig-4.6.3 .config 6. make oldconfig 7. make 8. Edit setenv.h, if necessary, so 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-M3 toolchain for Cygwin under Windows. NOTE: Unfortunately, the 4.6.3 EABI toolchain is not compatible with the the NXFLAT tools. See the top-level TODO file (under "Binary loaders") for more information about this problem. If you plan to use NXFLAT, please do not use the GCC 4.6.3 EABI toochain; instead use the GCC 4.3.3 OABI toolchain. See instructions below. NuttX OABI "buildroot" Toolchain ================================ The older, OABI buildroot toolchain is also available. To use the OABI toolchain: 1. When building the buildroot toolchain, either (1) modify the cortexm3-eabi-defconfig-4.6.3 configuration to use EABI (using 'make menuconfig'), or (2) use an exising OABI configuration such as cortexm3-defconfig-4.3.3 2. Modify the Make.defs file to use the OABI conventions: +CROSSDEV = arm-nuttx-elf- +ARCHCPUFLAGS = -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft +NXFLATLDFLAGS2 = $(NXFLATLDFLAGS1) -T$(TOPDIR)/binfmt/libnxflat/gnu-nxflat-gotoff.ld -no-check-sections -CROSSDEV = arm-nuttx-eabi- -ARCHCPUFLAGS = -mcpu=cortex-m3 -mthumb -mfloat-abi=soft -NXFLATLDFLAGS2 = $(NXFLATLDFLAGS1) -T$(TOPDIR)/binfmt/libnxflat/gnu-nxflat-pcrel.ld -no-check-sections NXFLAT Toolchain ================ If you are *not* using the NuttX buildroot toolchain and you want to use the NXFLAT tools, then you will still have to build a portion of the buildroot tools -- just the NXFLAT tools. The buildroot with the NXFLAT tools can be downloaded from the NuttX Bitbucket download site (https://bitbucket.org/nuttx/nuttx/downloads/). This GNU toolchain builds and executes in the Linux or Cygwin environment. 1. You must have already configured Nuttx in /nuttx. cd tools ./configure.sh lpcxpresso-lpc1768/ 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/cortexm3-defconfig-nxflat .config 6. make oldconfig 7. make 8. Edit setenv.h, if necessary, so that the PATH variable includes the path to the newly builtNXFLAT binaries. LEDs ==== The STM32Tiny board has only one software controllable LED. This LED can be used by the board port when CONFIG_ARCH_LEDS option is enabled. If enabled the LED is simply turned on when the board boots succesfully, and is blinking on panic / assertion failed. PWM === The STM32 Tiny has no real on-board PWM devices, but the board can be configured to output a pulse train using TIM3 CH2 on the GPIO line B.5 (connected to the LED). Please note that the CONFIG_STM32_TIM3_PARTIAL_REMAP option must be enabled in this case. UARTs ===== UART/USART PINS --------------- USART1 RX PA10 TX PA9 USART2 CK PA4 CTS PA0* RTS PA1 RX PA3 TX PA2 USART3 CK PB12* CTS PB13* RTS PB14* RX PB11 TX PB10 * theses IO lines are intended to be used by the wireless module on the board. Default USART/UART Configuration -------------------------------- USART1 (RX & TX only) is available through the RS-232 port on the board. A MAX232 chip converts voltage to RS-232 level. This serial port can be used to flash a firmware using the boot loader integrated in the MCU. Timer Inputs/Outputs ==================== TIM1 CH1 PA8 CH2 PA9* CH3 PA10* CH4 PA11* TIM2 CH1 PA0*, PA15, PA5 CH2 PA1, PB3 CH3 PA2, PB10* CH4 PA3, PB11 TIM3 CH1 PA6, PB4 CH2 PA7, PB5* CH3 PB0 CH4 PB1* TIM4 CH1 PB6* CH2 PB7 CH3 PB8 CH4 PB9* * Indicates pins that have other on-board functions and should be used only with care (See board datasheet). STM32 Tiny - 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_CORTEXM3=y CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory CONFIG_ARCH_CHIP=stm32 CONFIG_ARCH_CHIP_name - For use in C code to identify the exact chip: CONFIG_ARCH_CHIP_STM32F103C8=y CONFIG_ARCH_BOARD_STM32_CUSTOM_CLOCKCONFIG - Enables special STM32 clock configuration features. CONFIG_ARCH_BOARD_STM32_CUSTOM_CLOCKCONFIG=n CONFIG_ARCH_BOARD - Identifies the configs subdirectory and hence, the board that supports the particular chip or SoC. CONFIG_ARCH_BOARD=stm32_tiny CONFIG_ARCH_BOARD_name - For use in C code CONFIG_ARCH_BOARD_STM32_TINY=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=20480 (20Kb) 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_CALIBRATION - Enables some build in instrumentation that cause a 100 second delay during boot-up. This 100 second delay serves no purpose other than it allows you to calibratre CONFIG_ARCH_LOOPSPERMSEC. You simply use a stop watch to measure the 100 second delay then adjust CONFIG_ARCH_LOOPSPERMSEC until the delay actually is 100 seconds. Individual subsystems can be enabled: AHB --- CONFIG_STM32_CRC CONFIG_STM32_BKPSRAM APB1 ---- CONFIG_STM32_TIM2 CONFIG_STM32_TIM3 CONFIG_STM32_TIM4 CONFIG_STM32_WWDG CONFIG_STM32_IWDG CONFIG_STM32_SPI2 CONFIG_STM32_USART2 CONFIG_STM32_USART3 CONFIG_STM32_I2C1 CONFIG_STM32_I2C2 CONFIG_STM32_CAN1 CONFIG_STM32_PWR -- Required for RTC APB2 ---- CONFIG_STM32_TIM1 CONFIG_STM32_USART1 CONFIG_STM32_ADC1 CONFIG_STM32_ADC2 CONFIG_STM32_SPI1 Timer devices may be used for different purposes. One special purpose is to generate modulated outputs for such things as motor control. If CONFIG_STM32_TIMn is defined (as above) then the following may also be defined to indicate that the timer is intended to be used for pulsed output modulation or ADC conversion. Note that ADC require two definitions: Not only do you have to assign the timer (n) for used by the ADC, but then you also have to configure which ADC (m) it is assigned to. CONFIG_STM32_TIMn_PWM Reserve timer n for use by PWM, n=1,..,14 CONFIG_STM32_TIMn_ADC Reserve timer n for use by ADC, n=1,..,14 CONFIG_STM32_TIMn_ADCm Reserve timer n to trigger ADCm, n=1,..,14, m=1,..,3 For each timer that is enabled for PWM usage, we need the following additional configuration settings: CONFIG_STM32_TIMx_CHANNEL - Specifies the timer output channel {1,..,4} NOTE: The STM32 timers are each capable of generating different signals on each of the four channels with different duty cycles. That capability is not supported by this driver: Only one output channel per timer. JTAG Enable settings (by default only SW-DP is enabled): CONFIG_STM32_JTAG_FULL_ENABLE - Enables full SWJ (JTAG-DP + SW-DP) CONFIG_STM32_JTAG_NOJNTRST_ENABLE - Enables full SWJ (JTAG-DP + SW-DP) but without JNTRST. CONFIG_STM32_JTAG_SW_ENABLE - Set JTAG-DP disabled and SW-DP enabled STM32Tiny specific device driver settings CONFIG_U[S]ARTn_SERIAL_CONSOLE - selects the USARTn (n=1,2,3) for the console and ttys0 (default is the USART1). CONFIG_U[S]ARTn_RXBUFSIZE - Characters are buffered as received. This specific the size of the receive buffer CONFIG_U[S]ARTn_TXBUFSIZE - Characters are buffered before being sent. This specific the size of the transmit buffer CONFIG_U[S]ARTn_BAUD - The configure BAUD of the UART. Must be CONFIG_U[S]ARTn_BITS - The number of bits. Must be either 7 or 8. CONFIG_U[S]ARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity CONFIG_U[S]ARTn_2STOP - Two stop bits STM32Tiny CAN Configuration CONFIG_CAN - Enables CAN support (one or both of CONFIG_STM32_CAN1 or CONFIG_STM32_CAN2 must also be defined) CONFIG_CAN_EXTID - Enables support for the 29-bit extended ID. Default Standard 11-bit IDs. CONFIG_CAN_FIFOSIZE - The size of the circular buffer of CAN messages. Default: 8 CONFIG_CAN_NPENDINGRTR - The size of the list of pending RTR requests. Default: 4 CONFIG_CAN_LOOPBACK - A CAN driver may or may not support a loopback mode for testing. The STM32 CAN driver does support loopback mode. CONFIG_CAN1_BAUD - CAN1 BAUD rate. Required if CONFIG_STM32_CAN1 is defined. CONFIG_CAN2_BAUD - CAN1 BAUD rate. Required if CONFIG_STM32_CAN2 is defined. CONFIG_CAN_TSEG1 - The number of CAN time quanta in segment 1. Default: 6 CONFIG_CAN_TSEG2 - the number of CAN time quanta in segment 2. Default: 7 CONFIG_STM32_CAN_REGDEBUG - If CONFIG_DEBUG_FEATURES is set, this will generate an dump of all CAN registers. STM32Tiny SPI Configuration CONFIG_STM32_SPI_INTERRUPTS - Select to enable interrupt driven SPI support. Non-interrupt-driven, poll-waiting is recommended if the interrupt rate would be to high in the interrupt driven case. CONFIG_STM32_SPI_DMA - Use DMA to improve SPI transfer performance. Cannot be used with CONFIG_STM32_SPI_INTERRUPT. Configurations ============== Each STM32Tiny configuration is maintained in a sub-directory and can be selected as follow: cd tools ./configure.sh STM32Tiny/ cd - . ./setenv.sh If this is a Windows native build, then configure.bat should be used instead of configure.sh: configure.bat STM32Tiny\ Where is one of the following: nsh: --- Configures the NuttShell (nsh) located at apps/examples/nsh. This configuration enables a console on UART1. Support for builtin applications is enabled, but in the base configuration no builtin applications are selected (see NOTES below). 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. This example supports the PWM test (apps/examples/pwm) but this must be manually enabled by selecting: CONFIG_PWM=y : Enable the generic PWM infrastructure CONFIG_STM32_TIM3=y : Enable TIM3 CONFIG_STM32_TIM3_PWM=y : Use TIM3 to generate PWM output CONFIG_STM32_TIM3_PARTIAL_REMAP=y : Required to have the port B5 as timer PWM output (channel 2) CONFIG_STM32_TIM3_CHANNEL=2 See also apps/examples/README.txt Note that the only supported board configuration uses the board LED as PWM output. Special PWM-only debug options: CONFIG_DEBUG_PWM_INFO 7. USB Support (CDC/ACM device) CONFIG_STM32_OTGFS=y : STM32 OTG FS support CONFIG_USBDEV=y : USB device support must be enabled CONFIG_CDCACM=y : The CDC/ACM driver must be built CONFIG_NSH_BUILTIN_APPS=y : NSH built-in application support must be enabled CONFIG_NSH_ARCHINIT=y : To perform USB initialization 8. Using the USB console. The STM32Tiny NSH configuration can be set up to use a USB CDC/ACM (or PL2303) USB console. The normal way that you would configure the the USB console would be to change the .config file like this: CONFIG_STM32_OTGFS=y : STM32 OTG FS support CONFIG_USART2_SERIAL_CONSOLE=n : Disable the USART2 console CONFIG_DEV_CONSOLE=n : Inhibit use of /dev/console by other logic CONFIG_USBDEV=y : USB device support must be enabled CONFIG_CDCACM=y : The CDC/ACM driver must be built CONFIG_CDCACM_CONSOLE=y : Enable the CDC/ACM USB console. NOTE: When you first start the USB console, you have hit ENTER a few times before NSH starts. The logic does this to prevent sending USB data before there is anything on the host side listening for USB serial input. 9. Here is an alternative USB console configuration. The following configuration will also create a NSH USB console but this version will use /dev/console. Instead, it will use the normal /dev/ttyACM0 USB serial device for the console: CONFIG_STM32_OTGFS=y : STM32 OTG FS support CONFIG_USART2_SERIAL_CONSOLE=y : Keep the USART2 console CONFIG_DEV_CONSOLE=y : /dev/console exists (but NSH won't use it) CONFIG_USBDEV=y : USB device support must be enabled CONFIG_CDCACM=y : The CDC/ACM driver must be built CONFIG_CDCACM_CONSOLE=n : Don't use the CDC/ACM USB console. CONFIG_NSH_USBCONSOLE=y : Instead use some other USB device for the console The particular USB device that is used is: CONFIG_NSH_USBCONDEV="/dev/ttyACM0" The advantage of this configuration is only that it is easier to bet working. This alternative does has some side effects: - When any other device other than /dev/console is used for a user interface, linefeeds (\n) will not be expanded to carriage return / linefeeds (\r\n). You will need to set your terminal program to account for this. - /dev/console still exists and still refers to the serial port. So you can still use certain kinds of debug output (see include/debug.h, all of the debug output from interrupt handlers will be lost. - But don't enable USB debug output! Since USB is console is used for USB debug output and you are using a USB console, there will be infinite loops and deadlocks: Debug output generates USB debug output which generatates USB debug output, etc. If you want USB debug output, you should consider enabling USB trace (CONFIG_USBDEV_TRACE) and perhaps the USB monitor (CONFIG_USBMONITOR). See the usbnsh configuration below for more information on configuring USB trace output and the USB monitor. usbnsh: ------- This is another NSH example. If differs from other 'nsh' configurations in that this configurations uses a USB serial device for console I/O. 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. This configuration does have UART2 output enabled and set up as the system logging device: CONFIG_SYSLOG_CHAR=y : Use a character device for system logging CONFIG_SYSLOG_DEVPATH="/dev/ttyS0" : UART2 will be /dev/ttyS0 However, there is nothing to generate SYLOG output in the default configuration so nothing should appear on UART2 unless you enable some debug output or enable the USB monitor. 4. Enabling USB monitor SYSLOG output. If tracing is enabled, the USB device will save encoded trace output in in-memory buffer; if the USB monitor is enabled, that trace buffer will be periodically emptied and dumped to the system loggin device (UART2 in this configuraion): CONFIG_USBDEV_TRACE=y : Enable USB trace feature CONFIG_USBDEV_TRACE_NRECORDS=128 : Buffer 128 records in memory CONFIG_NSH_USBDEV_TRACE=n : No builtin tracing from NSH CONFIG_NSH_ARCHINIT=y : Automatically start the USB monitor CONFIG_USBMONITOR=y : Enable the USB monitor daemon CONFIG_USBMONITOR_STACKSIZE=2048 : USB monitor daemon stack size CONFIG_USBMONITOR_PRIORITY=50 : USB monitor daemon priority CONFIG_USBMONITOR_INTERVAL=2 : Dump trace data every 2 seconds CONFIG_USBMONITOR_TRACEINIT=y : Enable TRACE output CONFIG_USBMONITOR_TRACECLASS=y CONFIG_USBMONITOR_TRACETRANSFERS=y CONFIG_USBMONITOR_TRACECONTROLLER=y CONFIG_USBMONITOR_TRACEINTERRUPTS=y 5. By default, this project assumes that you are *NOT* using the DFU bootloader. Using the Prolifics PL2303 Emulation ------------------------------------ You could also use the non-standard PL2303 serial device instead of the standard CDC/ACM serial device by changing: CONFIG_CDCACM=y : Disable the CDC/ACM serial device class CONFIG_CDCACM_CONSOLE=y : The CDC/ACM serial device is NOT the console CONFIG_PL2303=y : The Prolifics PL2303 emulation is enabled CONFIG_PL2303_CONSOLE=y : The PL2303 serial device is the console