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README.txt |
README ====== This README discusses issues unique to NuttX configurations for the STMicro STM32140G-EVAL development board. Contents ======== - Development Environment - GNU Toolchain Options - IDEs - NuttX buildroot Toolchain - STM3240G-EVAL-specific Configuration Options - LEDs - Ethernet - PWM - CAN - 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. Testing was performed using the Cygwin environment because the Raisonance R-Link emulatator and some RIDE7 development tools were used and those tools works only under Windows. GNU Toolchain Options ===================== The NuttX make system has been modified to support the following different toolchain options. 1. The CodeSourcery GNU toolchain, 2. The devkitARM GNU toolchain, 3. Raisonance GNU toolchain, or 4. The NuttX buildroot Toolchain (see below). All testing has been conducted using the CodeSourcery toolchain for Windows. To use the 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_STM32_CODESOURCERYW=y : CodeSourcery under Windows CONFIG_STM32_CODESOURCERYL=y : CodeSourcery under Linux CONFIG_STM32_DEVKITARM=y : devkitARM under Windows CONFIG_STM32_RAISONANCE=y : Raisonance RIDE7 under Windows CONFIG_STM32_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), 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. 3. Dependencies are not made when using Windows versions of the GCC. This is because the dependencies are generated using Windows pathes which do not work with the Cygwin make. Support has been added for making dependencies with the windows-native toolchains. That support can be enabled by modifying your Make.defs file as follows: - MKDEP = $(TOPDIR)/tools/mknulldeps.sh + MKDEP = $(TOPDIR)/tools/mkdeps.sh --winpaths "$(TOPDIR)" If you have problems with the dependency build (for example, if you are not building on C:), then you may need to modify tools/mkdeps.sh NOTE 1: 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. NOTE 2: The devkitARM toolchain includes a version of MSYS make. Make sure that 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 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 SourceForge download site (https://sourceforge.net/project/showfiles.php?group_id=189573). This GNU toolchain builds and executes in the Linux or Cygwin environment. 1. You must have already configured Nuttx in <some-dir>/nuttx. cd tools ./configure.sh stm3240g-eval/<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 configs/cortexm3-defconfig-4.3.3 .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 detailed PLUS some special instructions that you will need to follow if you are building a Cortex-M3 toolchain for Cygwin under Windows. Ethernet ======== The Ethernet driver is configured to use the MII interface: Board Jumper Settings: Jumper Description JP8 To enable MII, JP8 should not be fitted. JP6 2-3: Enable MII interface mode JP5 2-3: Provide 25 MHz clock for MII or 50 MHz clock for RMII by MCO at PA8 SB1 Not used with MII LEDs ==== The STM3240G-EVAL board has four LEDs labeled LD1, LD2, LD3 and LD4 on the board.. These LEDs are not used by the board port unless CONFIG_ARCH_LEDS is defined. In that case, the usage by the board port is defined in include/board.h and src/up_leds.c. The LEDs are used to encode OS-related\ events as follows: SYMBOL Meaning LED1* LED2 LED3 LED4 ------------------- ----------------------- ------- ------- ------- ------ LED_STARTED NuttX has been started ON OFF OFF OFF LED_HEAPALLOCATE Heap has been allocated OFF ON OFF OFF LED_IRQSENABLED Interrupts enabled ON ON OFF OFF LED_STACKCREATED Idle stack created OFF OFF ON OFF LED_INIRQ In an interrupt** ON N/C N/C OFF LED_SIGNAL In a signal handler*** N/C ON N/C OFF LED_ASSERTION An assertion failed ON ON N/C OFF LED_PANIC The system has crashed N/C N/C N/C ON LED_IDLE STM32 is is sleep mode (Optional, not used) * If LED1, LED2, LED3 are statically on, then NuttX probably failed to boot and these LEDs will give you some indication of where the failure was ** The normal state is LED3 ON and LED1 faintly glowing. This faint glow is because of timer interupts that result in the LED being illuminated on a small proportion of the time. *** LED2 may also flicker normally if signals are processed. PWM === The STM3240G-Eval has no real on-board PWM devices, but the board can be configured to output a pulse train using timer output pins. The following pins have been use to generate PWM output (see board.h for some other candidates): TIM4 CH2. Pin PD13 is used by the FSMC (FSMC_A18) and is also connected to the Motor Control Connector (CN5) just for this purpose. If FSMC is not enabled, then FSMC_A18 will not be used (and will be tri-stated from the LCD). CONFIGURATION: CONFIG_STM32_TIM4=y CONFIG_PWM=n CONFIG_PWM_PULSECOUNT=n CONFIG_STM32_TIM4_PWM=y CONFIG_STM32_TIM4_CHANNEL=2 ACCESS: Daughterboard Extension Connector, CN3, pin 32 Ground is available on CN3, pin1 NOTE: TIM4 hardware will not support pulse counting. TIM8 CH4: Pin PC9 is used by the microSD card (MicroSDCard_D1) and I2S (I2S_CKIN) but can be completely disconnected from both by opening JP16. CONFIGURATION: CONFIG_STM32_TIM8=y CONFIG_PWM=n CONFIG_PWM_PULSECOUNT=y CONFIG_STM32_TIM8_PWM=y CONFIG_STM32_TIM8_CHANNEL=4 ACCESS: Daughterboard Extension Connector, CN3, pin 17 Ground is available on CN3, pin1 CAN === Connector 10 (CN10) is DB-9 male connector that can be used with CAN1 or CAN2. JP10 connects CAN1_RX or CAN2_RX to the CAN transceiver JP3 connects CAN1_TX or CAN2_TX to the CAN transceiver CAN signals are then available on CN10 pins: CN10 Pin 7 = CANH CN10 Pin 2 = CANL Mapping to STM32 GPIO pins: PD0 = FSMC_D2 & CAN1_RX PD1 = FSMC_D3 & CAN1_TX PB13 = ULPI_D6 & CAN2_TX PB5 = ULPI_D7 & CAN2_RX Configuration Options: CONFIG_CAN - Enables CAN support (one or both of CONFIG_STM32_CAN1 or CONFIG_STM32_CAN2 must also be defined) 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_STM32_CAN1 - Enable support for CAN1 CONFIG_CAN1_BAUD - CAN1 BAUD rate. Required if CONFIG_STM32_CAN1 is defined. CONFIG_STM32_CAN2 - Enable support for CAN2 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_CAN_REGDEBUG - If CONFIG_DEBUG is set, this will generate an dump of all CAN registers. STM3240G-EVAL-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_CORTEXM4=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_STM32F407IG=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=stm3240g_eval (for the STM3240G-EVAL development board) CONFIG_ARCH_BOARD_name - For use in C code CONFIG_ARCH_BOARD_STM3240G_EVAL=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_DRAM_SIZE - Describes the installed DRAM (SRAM in this case): CONFIG_DRAM_SIZE=0x00010000 (64Kb) CONFIG_DRAM_START - The start address of installed DRAM CONFIG_DRAM_START=0x20000000 CONFIG_DRAM_END - Last address+1 of installed RAM CONFIG_DRAM_END=(CONFIG_DRAM_START+CONFIG_DRAM_SIZE) CONFIG_ARCH_IRQPRIO - The STM3240xxx supports interrupt prioritization CONFIG_ARCH_IRQPRIO=y CONFIG_ARCH_FPU - The STM3240xxx supports a floating point unit (FPU) CONFIG_ARCH_FPU=y 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. 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: AHB1 ---- CONFIG_STM32_CRC CONFIG_STM32_BKPSRAM CONFIG_STM32_CCMDATARAM CONFIG_STM32_DMA1 CONFIG_STM32_DMA2 CONFIG_STM32_ETHMAC CONFIG_STM32_OTGHS AHB2 ---- CONFIG_STM32_DCMI CONFIG_STM32_CRYP CONFIG_STM32_HASH CONFIG_STM32_RNG CONFIG_STM32_OTGFS AHB3 ---- CONFIG_STM32_FSMC APB1 ---- CONFIG_STM32_TIM2 CONFIG_STM32_TIM3 CONFIG_STM32_TIM4 CONFIG_STM32_TIM5 CONFIG_STM32_TIM6 CONFIG_STM32_TIM7 CONFIG_STM32_TIM12 CONFIG_STM32_TIM13 CONFIG_STM32_TIM14 CONFIG_STM32_WWDG CONFIG_STM32_SPI2 CONFIG_STM32_SPI3 CONFIG_STM32_USART2 CONFIG_STM32_USART3 CONFIG_STM32_UART4 CONFIG_STM32_UART5 CONFIG_STM32_I2C1 CONFIG_STM32_I2C2 CONFIG_STM32_I2C3 CONFIG_STM32_CAN1 CONFIG_STM32_CAN2 CONFIG_STM32_DAC1 CONFIG_STM32_DAC2 CONFIG_STM32_PWR -- Required for RTC APB2 ---- CONFIG_STM32_TIM1 CONFIG_STM32_TIM8 CONFIG_STM32_USART1 CONFIG_STM32_USART6 CONFIG_STM32_ADC1 CONFIG_STM32_ADC2 CONFIG_STM32_ADC3 CONFIG_STM32_SDIO CONFIG_STM32_SPI1 CONFIG_STM32_SYSCFG CONFIG_STM32_TIM9 CONFIG_STM32_TIM10 CONFIG_STM32_TIM11 Timer and I2C devices may need to the following to force power to be applied unconditionally at power up. (Otherwise, the device is powered when it is initialized). CONFIG_STM32_FORCEPOWER 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, ADC conversion, or DAC conversion. Note that ADC/DAC require two definition: Not only do you have to assign the timer (n) for used by the ADC or DAC, but then you also have to configure which ADC or DAC (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 CONFIG_STM32_TIMn_DAC Reserve timer n for use by DAC, n=1,..,14 CONFIG_STM32_TIMn_DACm Reserve timer n to trigger DACm, n=1,..,14, m=1,..,2 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 JTAG-DP and SW-DP are disabled): 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 STM3240xxx specific device driver settings CONFIG_U[S]ARTn_SERIAL_CONSOLE - selects the USARTn (n=1,2,3) or UART m (m=4,5) 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 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. CONFIG_SDIO_DMA - Support DMA data transfers. Requires CONFIG_STM32_SDIO and CONFIG_STM32_DMA2. CONFIG_SDIO_PRI - Select SDIO interrupt prority. Default: 128 CONFIG_SDIO_DMAPRIO - Select SDIO DMA interrupt priority. Default: Medium CONFIG_SDIO_WIDTH_D1_ONLY - Select 1-bit transfer mode. Default: 4-bit transfer mode. CONFIG_STM32_PHYADDR - The 5-bit address of the PHY on the board CONFIG_STM32_MII - Support Ethernet MII interface CONFIG_STM32_MII_MCO1 - Use MCO1 to clock the MII interface CONFIG_STM32_MII_MCO2 - Use MCO2 to clock the MII interface CONFIG_STM32_RMII - Support Ethernet RMII interface CONFIG_STM32_AUTONEG - Use PHY autonegotion to determine speed and mode CONFIG_STM32_ETHFD - If CONFIG_STM32_AUTONEG is not defined, then this may be defined to select full duplex mode. Default: half-duplex CONFIG_STM32_ETH100MBPS - If CONFIG_STM32_AUTONEG is not defined, then this may be defined to select 100 MBps speed. Default: 10 Mbps CONFIG_STM32_PHYSR - This must be provided if CONFIG_STM32_AUTONEG is defined. The PHY status register address may diff from PHY to PHY. This configuration sets the address of the PHY status register. CONFIG_STM32_PHYSR_SPEED - This must be provided if CONFIG_STM32_AUTONEG is defined. This provides bit mask indicating 10 or 100MBps speed. CONFIG_STM32_PHYSR_100MBPS - This must be provided if CONFIG_STM32_AUTONEG is defined. This provides the value of the speed bit(s) indicating 100MBps speed. CONFIG_STM32_PHYSR_MODE - This must be provided if CONFIG_STM32_AUTONEG is defined. This provide bit mask indicating full or half duplex modes. CONFIG_STM32_PHYSR_FULLDUPLEX - This must be provided if CONFIG_STM32_AUTONEG is defined. This provides the value of the mode bits indicating full duplex mode. CONFIG_STM32_ETH_PTP - Precision Time Protocol (PTP). Not supported but some hooks are indicated with this condition. STM3240G-EVAL CAN Configuration CONFIG_CAN - Enables CAN support (one or both of CONFIG_STM32_CAN1 or CONFIG_STM32_CAN2 must also be defined) 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_CAN_REGDEBUG - If CONFIG_DEBUG is set, this will generate an dump of all CAN registers. STM3240G-EVAL LCD Hardware Configuration Configurations ============== Each STM3240G-EVAL configuration is maintained in a sudirectory and can be selected as follow: cd tools ./configure.sh stm3240g-eval/<subdir> cd - . ./setenv.sh Where <subdir> is one of the following: dhcpd: ----- This builds the DCHP server using the apps/examples/dhcpd application (for execution from FLASH.) See apps/examples/README.txt for information about the dhcpd example. The server address is 10.0.0.1 and it serves IP addresses in the range 10.0.0.2 through 10.0.0.17 (all of which, of course, are configurable). CONFIG_STM32_CODESOURCERYW=y : CodeSourcery under Windows nettest: ------- This configuration directory may be used to verify networking performance using the STM32's Ethernet controller. It uses apps/examples/nettest to excercise the TCP/IP network. CONFIG_EXAMPLE_NETTEST_SERVER=n : Target is configured as the client CONFIG_EXAMPLE_NETTEST_PERFORMANCE=y : Only network performance is verified. CONFIG_EXAMPLE_NETTEST_IPADDR=(10<<24|0<<16|0<<8|2) : Target side is IP: 10.0.0.2 CONFIG_EXAMPLE_NETTEST_DRIPADDR=(10<<24|0<<16|0<<8|1) : Host side is IP: 10.0.0.1 CONFIG_EXAMPLE_NETTEST_CLIENTIP=(10<<24|0<<16|0<<8|1) : Server address used by which ever is client. ostest: ------ This configuration directory, performs a simple OS test using examples/ostest. By default, this project assumes that you are using the DFU bootloader. CONFIG_STM32_CODESOURCERYW=y : CodeSourcery under Windows nsh: --- Configures the NuttShell (nsh) located at apps/examples/nsh. The Configuration enables both the serial and telnet NSH interfaces. CONFIG_STM32_CODESOURCERYW=y : CodeSourcery under Windows CONFIG_NSH_DHCPC=n : DHCP is disabled CONFIG_NSH_IPADDR=(10<<24|0<<16|0<<8|2) : Target IP address 10.0.0.2 CONFIG_NSH_DRIPADDR=(10<<24|0<<16|0<<8|1) : Host IP address 10.0.0.1 NOTES: 1. This example assumes that a network is connected. During its initialization, it will try to negotiate the link speed. If you have no network connected when you reset the board, there will be a long delay (maybe 30 seconds?) before anything happens. That is the timeout before the networking finally gives up and decides that no network is available. 2. This example supports the ADC test (apps/examples/adc) but this must be manually enabled by selecting: CONFIG_ADC=y : Enable the generic ADC infrastructure CONFIG_STM32_ADC3=y : Enable ADC3 CONFIG_STM32_TIM1=y : Enable Timer 1 CONFIG_STM32_TIM1_ADC=y : Indicate that timer 1 will be used to trigger an ADC CONFIG_STM32_TIM1_ADC3=y : Assign timer 1 to drive ADC3 sampling CONFIG_STM32_ADC3_SAMPLE_FREQUENCY=100 : Select a sampling frequency See also apps/examples/README.txt General debug for analog devices (ADC/DAC): CONFIG_DEBUG_ANALOG 3. This example supports the PWM test (apps/examples/pwm) but this must be manually enabled by selecting eeither CONFIG_PWM=y : Enable the generic PWM infrastructure CONFIG_PWM_PULSECOUNT=n : Disable to support for TIM1/8 pulse counts CONFIG_STM32_TIM4=y : Enable TIM4 CONFIG_STM32_TIM4_PWM=y : Use TIM4 to generate PWM output CONFIG_STM32_TIM4_CHANNEL=2 : Select output on TIM4, channel 2 If CONFIG_STM32_FSMC is disabled, output will appear on CN3, pin 32. Ground is available on CN3, pin1. Or.. CONFIG_PWM=y : Enable the generic PWM infrastructure CONFIG_PWM_PULSECOUNT=y : Enable to support for TIM1/8 pulse counts CONFIG_STM32_TIM8=y : Enable TIM8 CONFIG_STM32_TIM8_PWM=y : Use TIM8 to generate PWM output CONFIG_STM32_TIM8_CHANNEL=4 : Select output on TIM8, channel 4 If CONFIG_STM32_FSMC is disabled, output will appear on CN3, pin 17 Ground is available on CN23 pin1. See also include/board.h and apps/examples/README.txt Special PWM-only debug options: CONFIG_DEBUG_PWM 4. This example supports the CAN loopback test (apps/examples/can) but this must be manually enabled by selecting: CONFIG_CAN=y : Enable the generic CAN infrastructure CONFIG_STM32_CAN1=y : Enable CAN1 CONFIG_CAN_LOOPBACK=y : Enable CAN loopback mode See also apps/examples/README.txt Special CAN-only debug options: CONFIG_DEBUG_CAN CONFIG_CAN_REGDEBUG