replace *(.init_array .init_array.*) with KEEP(*(.init_array .init_array.*)).
The KEEP statement within a linker script will instruct the linker to keep the specified section, even if no symbols inside it are referenced. This statement is used within the SECTIONS section of the linker script. This becomes relevant when garbage collection is performed at link time, enabled by passing the --gc-sections switch to the linker. The KEEP statement instructs the linker to use the specified section as a root node when creating a dependency graph, looking for unused sections. Essentially forcing the section to be marked as used.
Signed-off-by: cuiziwei <cuiziwei@xiaomi.com>
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README
======
This README discusses issues unique to NuttX configurations for the STMicro
Nucleo-144 board for STM32L4 chips.
Contents
========
- Nucleo-144 Boards
- Nucleo L496ZG
- Hardware
- Button
- LED
- U[S]ARTs and Serial Consoles
- SPI
- SDIO - MMC
- SPI Test
- Configurations
nsh
Nucleo-144 Boards:
=================
The Nucleo-144 is a standard board for use with several STM32 parts in the
LQFP144 package. Variants with a STM32L4 MCU include:
STM32 Part Board Variant Name
------------- ------------------
STM32L496ZGT6 NUCLEO-L496ZG
STM32L496ZGT6P NUCLEO-L496ZG-P
STM32L4A6ZGT6 NUCLEO-L4A6ZG
STM32L4R5ZIT6 NUCLEO-L4R5ZI
STM32L4R5ZIT6P NUCLEO-L4R5ZI-P
------------- ------------------
This directory supports only the STM32L4 variants of Nucleo-144. For others,
see boards/arm/stm32f7/nucleo-144 configuration.
Please read the User Manual UM2179: Getting started with STM32 Nucleo board
software development tools and take note of the Powering options for the
board (6.3 Power supply and power selection) and the Solder bridges based
hardware configuration changes that are configurable (6.11 Solder bridges).
Also note that UM1727 is not valid for L4 Nucleo-144 boards!
Common Board Features:
---------------------
Peripherals: 8 leds, 2 push button (3 LEDs, 1 button) under software
control
Debug: STLINK/V2-1 debugger/programmer Uses a STM32F103CB to
provide a ST-Link for programming, debug similar to the
OpenOcd FTDI function - USB to JTAG front-end.
Expansion I/F: ST Zio and Extended Ardino and Morpho Headers
Nucleo L496ZG
=============
ST Nucleo L496ZG board from ST Micro is supported. See
http://www.st.com/content/st_com/en/products/evaluation-tools/product-evaluation-tools/mcu-eval-tools/stm32-mcu-eval-tools/stm32-mcu-nucleo/nucleo-l496zg.html
The Nucleo L496ZG order part number is NUCLEO-L496ZG. It is one member of
the STM32 Nucleo-144 board family.
NUCLEO-L496ZG Features:
----------------------
Microprocessor: STM32L496ZGT6 Core: ARM 32-bit Cortex®-M4 CPU with FPU,
80 MHz, MPU, and DSP instructions.
Memory: 1024 KB Flash 320KB of SRAM (including 64KB of SRAM2)
ADC: 3×12-bit: up to 24 channels
DMA: 2 X 7-stream DMA controllers with FIFOs and burst support
Timers: Up to 13 timers: (2x 16-bit lowpower), two 32-bit timers,
2x watchdogs, SysTick
GPIO: 114 I/O ports with interrupt capability
LCD: LCD-TFT Controller, Parallel interface
I2C: 4 × I2C interfaces (SMBus/PMBus)
U[S]ARTs: 3 USARTs, 2 UARTs (27 Mbit/s, ISO7816 interface, LIN, IrDA,
modem control)
SPI/12Ss: 6/3 (simplex) (up to 50 Mbit/s), 3 with muxed simplex I2S
for audio class accuracy via internal audio PLL or external
clock
QSPI: Dual mode Quad-SPI
SAIs: 2 Serial Audio Interfaces
CAN: 2 X CAN interface
SDMMC interface
USB: USB 2.0 full-speed device/host/OTG controller with on-chip
PHY
Camera Interface: 8/14 Bit
CRC calculation unit
TRG: True random number generator
RTC
See https://developer.mbed.org/platforms/ST-Nucleo-L496ZG for additional
information about this board.
Hardware
========
< Section needs updating >
GPIO - there are 144 I/O lines on the STM32L4xxZx with various pins pined out
on the Nucleo 144.
Keep in mind that:
1) The I/O is 3.3 Volt not 5 Volt like on the Arduino products.
2) The Nucleo-144 board family has 3 pages of Solder Bridges AKA Solder
Blobs (SB) that can alter the factory configuration. We will note SB
in effect but will assume the factory default settings.
Our main concern is establishing a console and LED utilization for
debugging.
Buttons
-------
B1 USER: the user button is connected to the I/O PC13 (Tamper support, SB173
ON and SB180 OFF)
LEDs
----
The Board provides a 3 user LEDs, LD1-LD3
LED1 (Green) PB_0 (SB120 ON and SB119 OFF)
LED2 (Blue) PB_7 (SB139 ON)
LED3 (Red) PB_14 (SP118 ON)
- When the I/O is HIGH value, the LEDs are on.
- When the I/O is LOW, the LEDs are off.
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/stm32_autoleds.c. The LEDs are used to encode OS
related events as follows when the LEDs are available:
SYMBOL Meaning RED GREEN BLUE
------------------- ----------------------- --- ----- ----
LED_STARTED NuttX has been started OFF OFF OFF
LED_HEAPALLOCATE Heap has been allocated OFF OFF ON
LED_IRQSENABLED Interrupts enabled OFF ON OFF
LED_STACKCREATED Idle stack created OFF ON ON
LED_INIRQ In an interrupt NC NC ON (momentary)
LED_SIGNAL In a signal handler NC ON OFF (momentary)
LED_ASSERTION An assertion failed ON NC ON (momentary)
LED_PANIC The system has crashed ON OFF OFF (flashing 2Hz)
LED_IDLE MCU is is sleep mode ON OFF OFF
OFF - means that the OS is still initializing. Initialization is very fast
so if you see this at all, it probably means that the system is
hanging up somewhere in the initialization phases.
GREEN - This means that the OS completed initialization.
BLUE - Whenever and interrupt or signal handler is entered, the BLUE LED is
illuminated and extinguished when the interrupt or signal handler
exits.
VIOLET - If a recovered assertion occurs, the RED and blue LED will be
illuminated briefly while the assertion is handled. You will
probably never see this.
Flashing RED - In the event of a fatal crash, all other LEDs will be
extinguished and RED LED will FLASH at a 2Hz rate.
Thus if the GREEN LED is lit, NuttX has successfully booted and is,
apparently, running normally. If the RED LED is flashing at
approximately 2Hz, then a fatal error has been detected and the system has
halted.
Serial Consoles
===============
USART3
------
Default board is configured to use USART3 as console.
Pins and Connectors:
FUNC GPIO Connector
Pin NAME
---- --- ------- ----
TXD: PC4 CN8-9, A4
RXD: PC5 CN8-11, A5
---- --- ------- ----
You must use a 3.3 TTL to RS-232 converter or a USB to 3.3V TTL
Nucleo 144 FTDI TTL-232R-3V3
------------- -------------------
TXD - CN8-9 - RXD - Pin 5 (Yellow)
RXD - CN8-11 - TXD - Pin 4 (Orange)
GND - GND Pin 1 (Black)
------------- -------------------
*Note you will be reverse RX/TX
Use make menuconfig to configure USART3 as the console:
CONFIG_STM32L4_USART3=y
CONFIG_USART3_SERIALDRIVER=y
CONFIG_USART3_SERIAL_CONSOLE=y
CONFIG_USART3_RXBUFSIZE=256
CONFIG_USART3_TXBUFSIZE=256
CONFIG_USART3_BAUD=115200
CONFIG_USART3_BITS=8
CONFIG_USART3_PARITY=0
CONFIG_USART3_2STOP=0
USART2
------
USART 2 could be used as console as well.
Virtual COM Port
----------------
Yet another option is to use LPUART1 and the USB virtual COM port. This
option may be more convenient for long term development, but is painful
to use during board bring-up. However the LPUART peripheral has not yet
been tested for this board.
Solder Bridges. This configuration requires:
PG7 LPUART1 TX SB131 ON and SB195 OFF (Default)
PG8 LPUART1 RX SB130 ON and SB193 OFF (Default)
Default
-------
As shipped, the virtual COM port is enabled.
SPI
---
Since this board is so generic, having a quick way to vet the SPI
configuration seams in order. So the board provides a quick test
that can be selected vi CONFIG_NUCLEO_SPI_TEST that will initialize
the selected buses (SPI1-SPI3) and send some text on the bus at
application initialization time board_app_initialize.
SDIO
----
To test the SD performance one can use a SparkFun microSD Sniffer
from https://www.sparkfun.com/products/9419 or similar board
and connect it as follows:
VCC V3.3 CN11 16
GND GND CN11-8
CMD PD2 CN11-4
CLK PC12 CN11-3
DAT0 - PC8 CN12-2
DAT1 - PC9 CN12-1
DAT2 PC10 CN11-1
CD PC11 CN11-2
Configurations
==============
nsh:
----
Configures the NuttShell (nsh) located at apps/examples/nsh for the
Nucleo-144 boards. The Configuration enables the serial interfaces
on USART6. 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. If this is the initial configuration then execute
./tools/configure.sh nucleo-l496zg:nsh
in nuttx/ in order to start configuration process.
Caution: Doing this step more than once will overwrite .config with
the contents of the nucleo-l496zg/nsh/defconfig file.
c. Execute 'make oldconfig' in nuttx/ in order to refresh the
configuration.
d. Execute 'make menuconfig' in nuttx/ in order to start the
reconfiguration process.
e. Save the .config file to reuse it in the future starting at step d.
2. By default, this configuration uses the ARM GNU toolchain
for Linux. That can easily be reconfigured, of course.
CONFIG_HOST_LINUX=y : Builds under Linux
CONFIG_ARM_TOOLCHAIN_GNU_EABI=y : ARM GNU for Linux
3. Although the default console is LPUART1 (which would correspond to
the Virtual COM port) I have done all testing with the console
device configured for USART3 (see instruction above under "Serial
Consoles).
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