XXX all this needs review and update
README
======

This README discusses issues unique to NuttX configurations for the ST
STM32L476VG Discovery board from ST Micro. See

http://www.st.com/stm32l476g-disco

STM32L476VG:

Microprocessor: 32-bit ARM Cortex M4 at 80MHz STM32F476VGT6
Memory: 1024 KB Flash and 96+32 KB SRAM
ADC: 3x12-bit, 2.4 MSPS A/D converter: up to 24 channels
DMA: 16-stream DMA controllers with FIFOs and burst support
Timers: Up to 11 timers: up to eight 16-bit, two 32-bit timers, two
watchdog timers, and a SysTick timer
GPIO: Up to 51 I/O ports with interrupt capability
I2C: Up to 3 x I2C interfaces
USARTs: Up to 3 USARTs, 2 UARTs, 1 LPUART
SPIs: Up to 3 SPIs
SAIs: Up to 2 dual-channel audio interfaces
CAN interface
SDIO interface
QSPI interface
USB: USB 2.0 full-speed device/host/OTG controller with on-chip PHY
CRC calculation unit
RTC

Board features:

Peripherals: 2 led, 1 d-pad joystick, 2 x LED, LCD, USC OTG FS, SAI stereo
Digital Microphone, MEMS Accelerometer, Magnetometer,
Gyroscope, 128 Mbit QSPI Flash, current ammeter
Debug: Serial wire debug and JTAG interfaces

Uses a STM32F103 to provide a ST-Link for programming, debug similar to the
OpenOcd FTDI function - USB to JTAG front-end.

See http://mbed.org/platforms/ST-Nucleo-L476RG for more
information about these boards.

Contents
========

- mbed
- Hardware
- Button
- LED
- USARTs and Serial Consoles
- LQFP64
- mbed
- Shields
- Configurations

mbed
====

The Nucleo-F401RE includes boot loader from mbed:

https://mbed.org/platforms/ST-Nucleo-F401RE/
https://mbed.org/handbook/Homepage

Using the mbed loader:

1. Connect the Nucleo-F4x1RE to the host PC using the USB connector.
2. A new file system will appear called NUCLEO; open it with Windows
Explorer (assuming that you are using Windows).
3. Drag and drop nuttx.bin into the MBED window. This will load the
nuttx.bin binary into the Nucleo-F4x1RE. The NUCLEO window will
close then re-open and the Nucleo-F4x1RE will be running the new code.

Hardware
========

GPIO
----
SERIAL_TX=PA_2 USER_BUTTON=PC_13
SERIAL_RX=PA_3 LED1 =PA_5

A0=PA_0 USART2RX D0=PA_3 D8 =PA_9
A1=PA_1 USART2TX D1=PA_2 D9 =PC_7
A2=PA_4 D2=PA_10 WIFI_CS=D10=PB_6 SPI_CS
A3=PB_0 WIFI_INT=D3=PB_3 D11=PA_7 SPI_MOSI
A4=PC_1 SDCS=D4=PB_5 D12=PA_6 SPI_MISO
A5=PC_0 WIFI_EN=D5=PB_4 LED1=D13=PA_5 SPI_SCK
LED2=D6=PB_10 I2C1_SDA=D14=PB_9 Probe
D7=PA_8 I2C1_SCL=D15=PB_8 Probe

From: https://mbed.org/platforms/ST-Nucleo-F401RE/

Buttons
-------
B1 USER: the user button is connected to the I/O PC13 (pin 2) of the STM32
microcontroller.

LEDs
----
The Nucleo F401RE and Nucleo F411RE provide a single user LED, LD2. LD2
is the green LED connected to Arduino signal D13 corresponding to MCU I/O
PA5 (pin 21) or PB13 (pin 34) depending on the STM32target.

- When the I/O is HIGH value, the LED is on.
- When the I/O is LOW, the LED is 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/sam_leds.c. The LEDs are used to encode OS-related
events as follows when the red LED (PE24) is available:

SYMBOL Meaning LD2
------------------- ----------------------- -----------
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 No change
LED_SIGNAL In a signal handler No change
LED_ASSERTION An assertion failed No change
LED_PANIC The system has crashed Blinking
LED_IDLE MCU is is sleep mode Not used

Thus if LD2, NuttX has successfully booted and is, apparently, running
normally. If LD2 is flashing at approximately 2Hz, then a fatal error
has been detected and the system has halted.

Serial Consoles
===============

USART1
------
Pins and Connectors:

RXD: PA11 CN10 pin 14
PB7 CN7 pin 21
TXD: PA10 CN9 pin 3, CN10 pin 33
PB6 CN5 pin 3, CN10 pin 17

NOTE: You may need to edit the include/board.h to select different USART1
pin selections.

TTL to RS-232 converter connection:

Nucleo CN10 STM32F4x1RE
----------- ------------
Pin 21 PA9 USART1_RX *Warning you make need to reverse RX/TX on
Pin 33 PA10 USART1_TX some RS-232 converters
Pin 20 GND
Pin 8 U5V

To configure USART1 as the console:

CONFIG_STM32_USART1=y
CONFIG_USART1_SERIALDRIVER=y
CONFIG_USART1_SERIAL_CONSOLE=y
CONFIG_USART1_RXBUFSIZE=256
CONFIG_USART1_TXBUFSIZE=256
CONFIG_USART1_BAUD=115200
CONFIG_USART1_BITS=8
CONFIG_USART1_PARITY=0
CONFIG_USART1_2STOP=0

USART2
-----
Pins and Connectors:

RXD: PA3 CN9 pin 1 (See SB13, 14, 62, 63). CN10 pin 37
PD6
TXD: PA2 CN9 pin 2(See SB13, 14, 62, 63). CN10 pin 35
PD5

UART2 is the default in all of these configurations.

TTL to RS-232 converter connection:

Nucleo CN9 STM32F4x1RE
----------- ------------
Pin 1 PA3 USART2_RX *Warning you make need to reverse RX/TX on
Pin 2 PA2 USART2_TX some RS-232 converters

Solder Bridges. This configuration requires:

- SB62 and SB63 Closed: PA2 and PA3 on STM32 MCU are connected to D1 and D0
(pin 7 and pin 8) on Arduino connector CN9 and ST Morpho connector CN10
as USART signals. Thus SB13 and SB14 should be OFF.

- SB13 and SB14 Open: PA2 and PA3 on STM32F103C8T6 (ST-LINK MCU) are
disconnected to PA3 and PA2 on STM32 MCU.

To configure USART2 as the console:

CONFIG_STM32_USART2=y
CONFIG_USART2_SERIALDRIVER=y
CONFIG_USART2_SERIAL_CONSOLE=y
CONFIG_USART2_RXBUFSIZE=256
CONFIG_USART2_TXBUFSIZE=256
CONFIG_USART2_BAUD=115200
CONFIG_USART2_BITS=8
CONFIG_USART2_PARITY=0
CONFIG_USART2_2STOP=0

USART6
------
Pins and Connectors:

RXD: PC7 CN5 pin2, CN10 pin 19
PA12 CN10, pin 12
TXD: PC6 CN10, pin 4
PA11 CN10, pin 14

To configure USART6 as the console:

CONFIG_STM32_USART6=y
CONFIG_USART6_SERIALDRIVER=y
CONFIG_USART6_SERIAL_CONSOLE=y
CONFIG_USART6_RXBUFSIZE=256
CONFIG_USART6_TXBUFSIZE=256
CONFIG_USART6_BAUD=115200
CONFIG_USART6_BITS=8
CONFIG_USART6_PARITY=0
CONFIG_USART6_2STOP=0

Virtual COM Port
----------------
Yet another option is to use UART2 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.

Solder Bridges. This configuration requires:

- SB62 and SB63 Open: PA2 and PA3 on STM32 MCU are disconnected to D1
and D0 (pin 7 and pin 8) on Arduino connector CN9 and ST Morpho
connector CN10.

- SB13 and SB14 Closed: PA2 and PA3 on STM32F103C8T6 (ST-LINK MCU) are
connected to PA3 and PA2 on STM32 MCU to have USART communication
between them. Thus SB61, SB62 and SB63 should be OFF.

Configuring USART2 is the same as given above.

Question: What BAUD should be configure to interface with the Virtual
COM port? 115200 8N1?

Default
-------
As shipped, SB62 and SB63 are open and SB13 and SB14 closed, so the
virtual COM port is enabled.

Shields
=======

RS-232 from Cutedigi.com
------------------------
Supports a single RS-232 connected via

Nucleo CN9 STM32F4x1RE Cutedigi
----------- ------------ --------
Pin 1 PA3 USART2_RX RXD
Pin 2 PA2 USART2_TX TXD

Support for this shield is enabled by selecting USART2 and configuring
SB13, 14, 62, and 63 as described above under "Serial Consoles"

Itead Joystick Shield
---------------------
See http://imall.iteadstudio.com/im120417014.html for more information
about this joystick.

Itead Joystick Connection:

--------- ----------------- ---------------------------------
ARDUINO ITEAD NUCLEO-F4x1
PIN NAME SIGNAL SIGNAL
--------- ----------------- ---------------------------------
D3 Button E Output PB3
D4 Button D Output PB5
D5 Button C Output PB4
D6 Button B Output PB10
D7 Button A Output PA8
D8 Button F Output PA9
D9 Button G Output PC7
A0 Joystick Y Output PA0 ADC1_0
A1 Joystick X Output PA1 ADC1_1
--------- ----------------- ---------------------------------

All buttons are pulled on the shield. A sensed low value indicates
when the button is pressed.

NOTE: Button F cannot be used with the default USART1 configuration
because PA9 is configured for USART1_RX by default. Use select
different USART1 pins in the board.h file or select a different
USART or select CONFIG_NUCLEO_F401RE_AJOY_MINBUTTONS which will
eliminate all but buttons A, B, and C.

Itead Joystick Signal interpretation:

--------- ----------------------- ---------------------------
BUTTON TYPE NUTTX ALIAS
--------- ----------------------- ---------------------------
Button A Large button A JUMP/BUTTON 3
Button B Large button B FIRE/BUTTON 2
Button C Joystick select button SELECT/BUTTON 1
Button D Tiny Button D BUTTON 6
Button E Tiny Button E BUTTON 7
Button F Large Button F BUTTON 4
Button G Large Button G BUTTON 5
--------- ----------------------- ---------------------------

Itead Joystick configuration settings:

System Type -> STM32 Peripheral Support
CONFIG_STM32_ADC1=y : Enable ADC1 driver support

Drivers
CONFIG_ANALOG=y : Should be automatically selected
CONFIG_ADC=y : Should be automatically selected
CONFIG_INPUT=y : Select input device support
CONFIG_AJOYSTICK=y : Select analog joystick support

There is nothing in the configuration that currently uses the joystick.
For testing, you can add the following configuration options to enable the
analog joystick example at apps/examples/ajoystick:

CONFIG_NSH_ARCHINIT=y
CONFIG_EXAMPLES_AJOYSTICK=y
CONFIG_EXAMPLES_AJOYSTICK_DEVNAME="/dev/ajoy0"
CONFIG_EXAMPLES_AJOYSTICK_SIGNO=13

STATUS:
2014-12-04:
- Without ADC DMA support, it is not possible to sample both X and Y
with a single ADC. Right now, only one axis is being converted.
- There is conflicts with some of the Arduino data pins and the
default USART1 configuration. I am currently running with USART1
but with CONFIG_NUCLEO_F401RE_AJOY_MINBUTTONS to eliminate the
conflict.
- Current showstopper: I appear to be getting infinite interrupts as
soon as joystick button interrupts are enabled.

Configurations
==============

knsh:
----

This is identical to the nsh configuration below except that (1) NuttX
is built as a PROTECTED mode, monolithic module and the user applications
are built separately and, as a consequence, (2) some features that are
only availabled in the FLAT build are disabled.

It is recommends to use a special make command; not just 'make' but make
with the following two arguments:

make pass1 pass2

In the normal case (just 'make'), make will attempt to build both user-
and kernel-mode blobs more or less interleaved. That actual works!
However, for me it is very confusing so I prefer the above make command:
Make the user-space binaries first (pass1), then make the kernel-space
binaries (pass2)

NOTES:

1. At the end of the build, there will be several files in the top-level
NuttX build directory:

PASS1:
nuttx_user.elf - The pass1 user-space ELF file
nuttx_user.hex - The pass1 Intel HEX format file (selected in defconfig)
User.map - Symbols in the user-space ELF file

PASS2:
nuttx - The pass2 kernel-space ELF file
nuttx.hex - The pass2 Intel HEX file (selected in defconfig)
System.map - Symbols in the kernel-space ELF file

The J-Link programmer will except files in .hex, .mot, .srec, and .bin
formats.

2. Combining .hex files. If you plan to use the .hex files with your
debugger or FLASH utility, then you may need to combine the two hex
files into a single .hex file. Here is how you can do that.

a. The 'tail' of the nuttx.hex file should look something like this
(with my comments added):

$ tail nuttx.hex
# 00, data records
...
:10 9DC0 00 01000000000800006400020100001F0004
:10 9DD0 00 3B005A0078009700B500D400F300110151
:08 9DE0 00 30014E016D0100008D
# 05, Start Linear Address Record
:04 0000 05 0800 0419 D2
# 01, End Of File record
:00 0000 01 FF

Use an editor such as vi to remove the 05 and 01 records.

b. The 'head' of the nuttx_user.hex file should look something like
this (again with my comments added):

$ head nuttx_user.hex
# 04, Extended Linear Address Record
:02 0000 04 0801 F1
# 00, data records
:10 8000 00 BD89 01084C800108C8110208D01102087E
:10 8010 00 0010 00201C1000201C1000203C16002026
:10 8020 00 4D80 01085D80010869800108ED83010829
...

Nothing needs to be done here. The nuttx_user.hex file should
be fine.

c. Combine the edited nuttx.hex and un-edited nuttx_user.hex
file to produce a single combined hex file:

$ cat nuttx.hex nuttx_user.hex >combined.hex

Then use the combined.hex file with the to write the FLASH image.
If you do this a lot, you will probably want to invest a little time
to develop a tool to automate these steps.

nsh:
---
Configures the NuttShell (nsh) located at apps/examples/nsh for the
Nucleo-F401RE board. The Configuration enables the serial interfaces
on UART2. 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 Generic ARM EABI toolchain
for Linux. That can easily be reconfigured, of course.

CONFIG_HOST_LINUX=y : Builds under Linux
CONFIG_ARMV7M_TOOLCHAIN_GNU_EABIL=y : Generic EABI toolchain for Linux

3. Although the default console is USART2 (which would correspond to
the Virtual COM port) I have done all testing with the console
device configured for USART1 (see instruction above under "Serial
Consoles). I have been using a TTL-to-RS-232 converter.

4. This example has been used to verify the OTGFS functionality. USB is
not enabled in the default configuration but can be enabled with the
following settings:

CONFIG_STM32L4_OTGFS=y

CONFIG_USBDEV=y
CONFIG_USBDEV_SELFPOWERED=y

These will enable the USB CDC/ACM serial device

CONFIG_CDCACM=y
CONFIG_CDCACM_EP0MAXPACKET=64
CONFIG_CDCACM_EPINTIN=1
CONFIG_CDCACM_EPINTIN_FSSIZE=64
CONFIG_CDCACM_EPINTIN_HSSIZE=64
CONFIG_CDCACM_EPBULKOUT=3
CONFIG_CDCACM_EPBULKOUT_FSSIZE=64
CONFIG_CDCACM_EPBULKOUT_HSSIZE=512
CONFIG_CDCACM_EPBULKIN=2
CONFIG_CDCACM_EPBULKIN_FSSIZE=64
CONFIG_CDCACM_EPBULKIN_HSSIZE=512
CONFIG_CDCACM_NRDREQS=4
CONFIG_CDCACM_NWRREQS=4
CONFIG_CDCACM_BULKIN_REQLEN=96
CONFIG_CDCACM_RXBUFSIZE=257
CONFIG_CDCACM_TXBUFSIZE=193
CONFIG_CDCACM_VENDORID=0x0525
CONFIG_CDCACM_PRODUCTID=0xa4a7
CONFIG_CDCACM_VENDORSTR="NuttX"
CONFIG_CDCACM_PRODUCTSTR="CDC/ACM Serial"

CONFIG_SERIAL_REMOVABLE=y

These will enable the USB serial example at apps/examples/usbserial

CONFIG_BOARDCTL_USBDEVCTRL=y

CONFIG_EXAMPLES_USBSERIAL=y
CONFIG_EXAMPLES_USBSERIAL_BUFSIZE=512
CONFIG_EXAMPLES_USBSERIAL_TRACEINIT=y
CONFIG_EXAMPLES_USBSERIAL_TRACECLASS=y
CONFIG_EXAMPLES_USBSERIAL_TRACETRANSFERS=y
CONFIG_EXAMPLES_USBSERIAL_TRACECONTROLLER=y
CONFIG_EXAMPLES_USBSERIAL_TRACEINTERRUPTS=y

Optional USB debug features:

CONFIG_DEBUG_FEATURES=y
CONFIG_DEBUG_USB=y
CONFIG_ARCH_USBDUMP=y
CONFIG_USBDEV_TRACE=y
CONFIG_USBDEV_TRACE_NRECORDS=128
CONFIG_USBDEV_TRACE_STRINGS=y
CONFIG_USBDEV_TRACE_INITIALIDSET=y

CONFIG_NSH_USBDEV_TRACE=y
CONFIG_NSH_USBDEV_TRACEINIT=y
CONFIG_NSH_USBDEV_TRACECLASS=y
CONFIG_NSH_USBDEV_TRACETRANSFERS=y
CONFIG_NSH_USBDEV_TRACECONTROLLER=y
CONFIG_NSH_USBDEV_TRACEINTERRUPTS=y