ST STM32F746G-DISCO

This page discusses issues unique to NuttX configurations for the STMicro STM32F746G-DISCO development board featuring the STM32F746NGH6 MCU. The STM32F746NGH6 is a 216MHz Cortex-M7 operation with 1024Kb Flash memory and 300Kb SRAM. The board features:

• On-board ST-LINK/V2 for programming and debugging,

• Mbed-enabled (mbed.org)

• 4.3-inch 480x272 color LCD-TFT with capacitive touch screen

• Camera connector

• SAI audio codec

• Audio line in and line out jack

• Stereo speaker outputs

• Two ST MEMS microphones

• SPDIF RCA input connector

• Two pushbuttons (user and reset)

• 128-Mbit Quad-SPI Flash memory

• 128-Mbit SDRAM (64 Mbits accessible)

• Connector for microSD card

• RF-EEPROM daughterboard connector

• USB OTG HS with Micro-AB connectors

• USB OTG FS with Micro-AB connectors

• Ethernet connector compliant with IEEE-802.3-2002

Refer to the http://www.st.com website for further information about this board (search keyword: stm32f746g-disco)

Development Environment

The Development environments for the STM32F746G-DISCO board are identical to the environments for other STM32F boards. For full details on the environment options and setup, see the README.txt file in the boards/arm/stm32f7/stm32f746g-disco directory.

LEDs and Buttons

LEDs

The STM32F746G-DISCO board has numerous LEDs but only one, LD1 located near the reset button, that can be controlled by software (LD2 is a power indicator, LD3-6 indicate USB status, LD7 is controlled by the ST-Link).

LD1 is controlled by PI1 which is also the SPI2_SCK at the Arduino interface. One end of LD1 is grounded so a high output on PI1 will illuminate the LED.

This LED is 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/stm32_leds.c. The LEDs are used to encode OS-related events as follows:

SYMBOL	Meaning	LD1
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 LD1 is statically on, NuttX has successfully booted and is, apparently, running normally. If LD1 is flashing at approximately 2Hz, then a fatal error has been detected and the system has halted.

Buttons

Pushbutton B1, labelled “User”, is connected to GPIO PI11. A high value will be sensed when the button is depressed.

Serial Console

The STM32F469G-DISCO uses USART1 connected to “Virtual COM”, so when you plug it on your computer it will be detected as a USB port (i.e. ttyACM0):

V.COM	FUNCTION	GPIO
RXD	USART1_RX	PB7
TXD	USART1_TX	PA9

All you need to do after flashing NuttX on this board is use a serial console tool (minicom, picocom, screen, hyperterminal, teraterm, putty, etc ) configured to 115200 8n1.

Configurations

Common Configuration Information

Each STM32F746G-DISCO configuration is maintained in a sub-directory and can be selected as follow:

tools/configure.sh stm32f746g-disco:<subdir>

Where <subdir> is one of the sub-directories listed below.

NOTES:

1. These configurations use the mconf-based configuration tool. To change this configuration using that tool, you should:

   1. Build and install the kconfig-mconf tool. See nuttx/README.txt see additional README.txt files in the NuttX tools repository.

   2. Execute ‘make menuconfig’ in nuttx/ in order to start the reconfiguration process.

2. By default, these configurations use the USART1 for the serial console. Pins are configured to that RX/TX are available at pins D0 and D1 of the Arduion connectors. This should be compatible with most RS-232 shields.

3. 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

   As of this writing (2015-03-11), full support is difficult to find for the Cortex-M7, but is supported by at least this release of the ARM GNU tools:

   https://launchpadlibrarian.net/209776344/release.txt

   hat 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 Directories

nsh

Configures the NuttShell (NSH) located at apps/examples/nsh. The Configuration enables the serial interfaces on USART1. Support for built-in applications is enabled, but in the base configuration no built-in applications are selected.

netnsh

This configuration is similar to the nsh but a lot more hardware peripherals are enabled, in particular Ethernet, as well as networking support. It is similar to the stm32f769i-disco/netnsh configuration. This configuration uses USART1 for the serial console. USART1 is connected to the ST-link virtual com inside board.h to remove the need of a extra serial connection to use this board.

lgvl

STM32F746G-DISCO LittlevGL demo example.

The LTDC is initialized during boot up. This configuration uses USART1 for the serial console. USART1 is connected to the ST-link virtual com inside board.h to remove the need of a extra serial connection to use this board. From the nsh command line execute the lvgldemo example:

nsh> lvgldemo

The test will execute the calibration process and then run the LittlevGL demo project.

STM32F746G-DISCO LTDC Framebuffer demo example

Configure and build

tools/configure.sh stm32f746g-disco:fb make

Configuration

This configuration provides 1 LTDC with 16bpp pixel format and a resolution of 480x272.

Loading

st-flash write nuttx.bin 0x8000000

Executing

The ltdc is initialized during boot up. Interaction with NSH is via the serial console provided by ST-LINK USB at 115200 8N1 baud. From the nsh comandline execute the fb example:

nsh> fb

The test will put a pattern of concentric squares in the framebuffer and terminate.

STM32F746G-DISCO NX Terminal example

Configure and build

tools/configure.sh stm32f746g-disco:nxterm make

Configuration

This configuration provides 1 LTDC with 16bpp pixel format and a resolution of 480x272.

Trickiest part of config is increasing max message size (CONFIG_MQ_MAXMSGSIZE=256). NX server - client communication cannot be established with default value 8 bytes.

Loading

st-flash write nuttx.bin 0x8000000

or

openocd -f interface/stlink.cfg -f target/stm32f7x.cfg telnet localhost 4444 > program nuttx verify reset

Executing

The ltdc is initialized during boot up. Interaction with NSH is via the serial console provided by ST-LINK USB at 115200 8N1 baud.

From the nsh comandline execute the example:

nsh> nxterm

The test will show terminal window on the screen.

STM32F746G-DISCO NX demo example

Configure and build:

tools/configure.sh stm32f746g-disco:nxdemo
make

Configuration

This configuration provides 1 LTDC with 16bpp pixel format and a resolution of 480x272.

Trickiest part of config is increasing max message size (CONFIG_MQ_MAXMSGSIZE=256). NX server - client communication cannot be established with default value 8 bytes.

Loading:

st-flash write nuttx.bin 0x8000000

or:

openocd -f interface/stlink.cfg -f target/stm32f7x.cfg
telnet localhost 4444
> program nuttx verify reset

Executing

The ltdc is initialized during boot up. Interaction with NSH is via the serial console provided by ST-LINK USB at 115200 8N1 baud.

There are two graphics examples provided in this configuration: - nxdemo - nxhello

Use help command to show list of examples available:

nsh> help

From the nsh comandline execute the example:

nsh> nxdemo

The test will draw animated lines, squares and circles on the device screen.