README
======
This README 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)
Contents
========
- STATUS
- Development Environment
- LEDs and Buttons
- Serial Console
- Porting STM32 F4 Drivers
- FPU
- STM32F746G-DISCO-specific Configuration Options
- Configurations
STATUS
======
2015-07-19: The basic NSH configuration is functional using a serial
console on USART6 and RS-232 shield. Very few other drivers are in
place yet.
2015-07-20: STM32 F7 Ethernet appears to be functional, but has had
only light testing.
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
config/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
==============
These configurations assume that you are using a standard Arduio RS-232
shield with the serial interface with RX on pin D0 and TX on pin D1:
-------- ---------------
STM32F7
ARDUIONO FUNCTION GPIO
-- ----- --------- -----
DO RX USART6_RX PC7
D1 TX USART6_TX PC6
-- ----- --------- -----
Porting STM32 F4 Drivers
========================
The STM32F746 is very similar to the STM32 F429 and many of the drivers
in the stm32/ directory could be ported here: ADC, BBSRAM, CAN, DAC,
DMA2D, FLASH, I2C, IWDG, LSE, LSI, LTDC, OTGFS, OTGHS, PM, Quadrature
Encoder, RNG, RTCC, SDMMC (was SDIO), Timer/counters, and WWDG.
Many of these drivers would be ported very simply; many ports would just
be a matter of copying files and some seach-and-replacement. Like:
1. Compare the two register definitions files; make sure that the STM32
F4 peripheral is identical (or nearly identical) to the F7
peripheral. If so then,
2. Copy the register definition file from the stm32/chip directory to
the stm32f7/chip directory, making name changes as appropriate and
updating the driver for any minor register differences.
3. Copy the corresponding C file (and possibly a matching .h file) from
the stm32/ directory to the stm32f7/ directory again with naming
changes and changes for any register differences.
4. Update the Make.defs file to include the new C file in the build.
For other files, particularly those that use DMA, the port will be
significantly more complex. That is because the STM32F7 has a D-Cache
and, as a result, we need to exercise much more care to maintain cache
coherency. There is a Wiki page discussing the issues of porting
drivers from the stm32/ to the stm32f7/ directories here:
http://www.nuttx.org/doku.php?id=wiki:howtos:port-drivers_stm32f7
FPU
===
FPU Configuration Options
-------------------------
There are two version of the FPU support built into the STM32 port.
1. Non-Lazy Floating Point Register Save
In this configuration floating point register save and restore is
implemented on interrupt entry and return, respectively. In this
case, you may use floating point operations for interrupt handling
logic if necessary. This FPU behavior logic is enabled by default
with:
CONFIG_ARCH_FPU=y
2. Lazy Floating Point Register Save.
An alternative mplementation only saves and restores FPU registers only
on context switches. This means: (1) floating point registers are not
stored on each context switch and, hence, possibly better interrupt
performance. But, (2) since floating point registers are not saved,
you cannot use floating point operations within interrupt handlers.
This logic can be enabled by simply adding the following to your .config
file:
CONFIG_ARCH_FPU=y
CONFIG_ARMV7M_LAZYFPU=y
STM32F746G-DISCO-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_CORTEXM7=y
CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory
CONFIG_ARCH_CHIP=stm32f7
CONFIG_ARCH_CHIP_name - For use in C code to identify the exact
chip:
CONFIG_ARCH_CHIP_STM32F746=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=stm32f746g-disco (for the STM32F746G-DISCO development board)
CONFIG_ARCH_BOARD_name - For use in C code
CONFIG_ARCH_BOARD_STM32F746G_DISCO=y
CONFIG_ARCH_LOOPSPERMSEC - Must be calibrated for correct operation
of delay loops
CONFIG_ENDIAN_BIG - should not be defined.
CONFIG_RAM_SIZE - Describes the installed DRAM (SRAM in this case):
CONFIG_RAM_SIZE=0x00010000 (64Kb)
CONFIG_RAM_START - The start address of installed SRAM (SRAM1)
CONFIG_RAM_START=0x20010000
CONFIG_RAM_SIZE=245760
This configurations use only SRAM1 for data storage. The heap includes
the remainder of SRAM1. If CONFIG_MM_REGIONS=2, then SRAM2 will be
included in the heap.
DTCM SRAM is never included in the heap because it cannot be used for
DMA. A DTCM allocator is available, however, so that DTCM can be
managed with dtcm_malloc(), dtcm_free(), etc.
In order to use FMC SRAM, the following additional things need to be
present in the NuttX configuration file:
CONFIG_STM32F7_FMC_SRAM - Indicates that SRAM is available via the
FMC (as opposed to an LCD or FLASH).
CONFIG_HEAP2_BASE - The base address of the SRAM in the FMC address space (hex)
CONFIG_HEAP2_SIZE - The size of the SRAM in the FMC address space (decimal)
CONFIG_ARCH_FPU - The STM32F746G-DISCO 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 calibrate
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:
APB1
----
CONFIG_STM32F7_TIM2 TIM2
CONFIG_STM32F7_TIM3 TIM3
CONFIG_STM32F7_TIM4 TIM4
CONFIG_STM32F7_TIM5 TIM5
CONFIG_STM32F7_TIM6 TIM6
CONFIG_STM32F7_TIM7 TIM7
CONFIG_STM32F7_TIM12 TIM12
CONFIG_STM32F7_TIM13 TIM13
CONFIG_STM32F7_TIM14 TIM14
CONFIG_STM32F7_LPTIM1 LPTIM1
CONFIG_STM32F7_RTC RTC
CONFIG_STM32F7_BKP BKP Registers
CONFIG_STM32F7_WWDG WWDG
CONFIG_STM32F7_IWDG IWDG
CONFIG_STM32F7_SPI2 SPI2
CONFIG_STM32F7_I2S2 I2S2
CONFIG_STM32F7_SPI3 SPI3
CONFIG_STM32F7_I2S3 I2S3
CONFIG_STM32F7_SPDIFRX SPDIFRX
CONFIG_STM32F7_USART2 USART2
CONFIG_STM32F7_USART3 USART3
CONFIG_STM32F7_UART4 UART4
CONFIG_STM32F7_UART5 UART5
CONFIG_STM32F7_I2C1 I2C1
CONFIG_STM32F7_I2C2 I2C2
CONFIG_STM32F7_I2C3 I2C3
CONFIG_STM32F7_I2C4 I2C4
CONFIG_STM32F7_CAN1 CAN1
CONFIG_STM32F7_CAN2 CAN2
CONFIG_STM32F7_HDMICEC HDMI-CEC
CONFIG_STM32F7_PWR PWR
CONFIG_STM32F7_DAC DAC
CONFIG_STM32F7_UART7 UART7
CONFIG_STM32F7_UART8 UART8
APB2
----
CONFIG_STM32F7_TIM1 TIM1
CONFIG_STM32F7_TIM8 TIM8
CONFIG_STM32F7_USART1 USART1
CONFIG_STM32F7_USART6 USART6
CONFIG_STM32F7_ADC ADC1 - ADC2 - ADC3
CONFIG_STM32F7_SDMMC1 SDMMC1
CONFIG_STM32F7_SPI1 SPI1
CONFIG_STM32F7_SPI4 SPI4
CONFIG_STM32F7_SYSCFG SYSCFG
CONFIG_STM32F7_EXTI EXTI
CONFIG_STM32F7_TIM9 TIM9
CONFIG_STM32F7_TIM10 TIM10
CONFIG_STM32F7_TIM11 TIM11
CONFIG_STM32F7_SPI5 SPI5
CONFIG_STM32F7_SPI6 SPI6
CONFIG_STM32F7_SAI1 SAI1
CONFIG_STM32F7_SAI2 SAI2
CONFIG_STM32F7_LTDC LCD-TFT
AHB1
----
CONFIG_STM32F7_CRC CRC
CONFIG_STM32F7_BKPSRAM BKPSRAM
CONFIG_STM32F7_DMA1 DMA1
CONFIG_STM32F7_DMA2 DMA2
CONFIG_STM32F7_ETHMAC Ethernet MAC
CONFIG_STM32F7_DMA2D Chrom-ART (DMA2D)
CONFIG_STM32F7_OTGHS USB OTG HS
AHB2
----
CONFIG_STM32F7_OTGFS USB OTG FS
CONFIG_STM32F7_DCMI DCMI
CONFIG_STM32F7_CRYP CRYP
CONFIG_STM32F7_HASH HASH
CONFIG_STM32F7_RNG RNG
AHB3
----
CONFIG_STM32F7_FMC FMC control registers
CONFIG_STM32F7_QUADSPI QuadSPI Control
Timer devices may be used for different purposes. One special purpose is
to generate modulated outputs for such things as motor control. If CONFIG_STM32F7_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_STM32F7_TIMn_PWM Reserve timer n for use by PWM, n=1,..,14
CONFIG_STM32F7_TIMn_ADC Reserve timer n for use by ADC, n=1,..,14
CONFIG_STM32F7_TIMn_ADCm Reserve timer n to trigger ADCm, n=1,..,14, m=1,..,3
CONFIG_STM32F7_TIMn_DAC Reserve timer n for use by DAC, n=1,..,14
CONFIG_STM32F7_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_STM32F7_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.
STM32F746G-DISCO 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
STM32F746G-DISCO CAN Configuration
CONFIG_CAN - Enables CAN support (one or both of CONFIG_STM32F7_CAN1 or
CONFIG_STM32F7_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_STM32F7_CAN1 is defined.
CONFIG_CAN2_BAUD - CAN1 BAUD rate. Required if CONFIG_STM32F7_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.
STM32F746G-DISCO SPI Configuration
CONFIG_STM32F7_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_STM32F7_SPI_DMA - Use DMA to improve SPI transfer performance.
Cannot be used with CONFIG_STM32F7_SPI_INTERRUPT.
STM32F746G-DISCO DMA Configuration
CONFIG_SDIO_DMA - Support DMA data transfers. Requires CONFIG_STM32F7_SDIO
and CONFIG_STM32F7_DMA2.
CONFIG_STM32_SDIO_DMAPRIO - Select SDIO DMA interrupt priority.
Default: Medium
CONFIG_STM32_SDIO_WIDTH_D1_ONLY - Select 1-bit transfer mode. Default:
4-bit transfer mode.
STM32 USB OTG FS Host Driver Support
Pre-requisites
CONFIG_USBDEV - Enable USB device support
CONFIG_USBHOST - Enable USB host support
CONFIG_STM32F7_OTGFS - Enable the STM32 USB OTG FS block
CONFIG_STM32F7_SYSCFG - Needed
CONFIG_SCHED_WORKQUEUE - Worker thread support is required
Options:
CONFIG_STM32F7_OTGFS_RXFIFO_SIZE - Size of the RX FIFO in 32-bit words.
Default 128 (512 bytes)
CONFIG_STM32F7_OTGFS_NPTXFIFO_SIZE - Size of the non-periodic Tx FIFO
in 32-bit words. Default 96 (384 bytes)
CONFIG_STM32F7_OTGFS_PTXFIFO_SIZE - Size of the periodic Tx FIFO in 32-bit
words. Default 96 (384 bytes)
CONFIG_STM32F7_OTGFS_DESCSIZE - Maximum size of a descriptor. Default: 128
CONFIG_STM32F7_OTGFS_SOFINTR - Enable SOF interrupts. Why would you ever
want to do that?
CONFIG_STM32F7_USBHOST_REGDEBUG - Enable very low-level register access
debug. Depends on CONFIG_DEBUG_FEATURES.
CONFIG_STM32F7_USBHOST_PKTDUMP - Dump all incoming and outgoing USB
packets. Depends on CONFIG_DEBUG_FEATURES.
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:
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, these configurations use the USART6 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 realease of
the ARM GNU tools:
https://launchpadlibrarian.net/209776344/release.txt
That 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_ARMV7M_TOOLCHAIN_GNU_EABIW=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 UART6. Support for
built-in applications is enabled, but in the base configuration no
built-in applications are selected.
nsh-ethernet
------------
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/nsh-ethernet
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.
