nuttx

The are no RS-232 drivers on-board. An RS-232 Click board is available:
https://shop.mikroe.com/click/interface/rs232 or you can cannot an off-
board TTL-to-RS-232 converter as follows:

USART2: mikroBUS1 PD6/RX and PD5/TX
USART3: mikroBUS2 PD9/RX and PD8TX

GND, 3.3V, and 5V. Are also available

By default, USART3 on mikroBUS2 is used as the serial console in each
configuration unless stated otherwise in the description of the
configuration.

LEDs
====

The Mikroe Clicker2 STM32 has two user controllable LEDs:

LD1/PE12, Active high output illuminates
LD2/PE15, Active high output illuminates

If CONFIG_ARCH_LEDS is not defined, then the user can control the LEDs in any
way. If CONFIG_ARCH_LEDs is defined, then NuttX will control the 2 LEDs on
board the Clicker2 for STM32. The following definitions describe how NuttX
controls the LEDs:

SYMBOL Meaning LED state
LD1 LD2
------------------- ----------------------- -------- --------
LED_STARTED NuttX has been started OFF OFF
LED_HEAPALLOCATE Heap has been allocated OFF OFF
LED_IRQSENABLED Interrupts enabled OFF OFF
LED_STACKCREATED Idle stack created ON OFF
LED_INIRQ In an interrupt N/C ON
LED_SIGNAL In a signal handler No change
LED_ASSERTION An assertion failed No change
LED_PANIC The system has crashed OFF Blinking
LED_IDLE STM32 is is sleep mode Not used

Thus is LD1 is illuminated, the Clicker2 has completed boot-up. IF LD2
is glowly softly, then interrupts are being taken; the level of illumination
depends amount of time processing interupts. If LD1 is off and LD2 is
blinking at about 2Hz, then the system has crashed.

Buttons
=======

The Mikroe Clicker2 STM32 has two buttons available to software:

T2/E0, Low sensed when pressed
T3/PA10, Low sensed when pressed

Using JTAG
==========

The Clicker2 comes with the mikroBootloader installed. That bootloader
has not been used and is possibly incompatible with the Clicker2-STM32
linker script at configs/clicker2-stm32/scripts/flash.ld. Often code must
be built to execute at an offset in to FLASH when a bootloader is used.
Certainly that is the case for the ST-Micro DFU bootloader but I am not
aware of the requirements for use with the mikroBootloader.

JTAG has been used in the development of this board support. The
Clicker2-STM32 board offers a 2x5 JTAG connector. You may use Dupont
jumpers to connect this port to JTAG as described here:

https://www.mikroe.com/how-to-use-st-link-v2-with-clicker-2-for-stm32-a-detailed-walkthrough/
http://www.playembedded.org/blog/en/2016/02/06/mikroe-clicker-2-for-stm32-and-stlink-v2/

NOTE that the FLASH is locked. You may need to follow the instructions at
the second link to unlock it (although I think you may be able to do this
with the ST-Micro ST-Link Utility as well).

You can avoid the mess of jumpers using the mikroProg to ST-Link v2 adapter
along with a 2x5, 10-wire ribbon cable connector:

https://shop.mikroe.com/add-on-boards/adapter/mikroprog-st-link-v2-adapter

OpenOCD can be used with the ST-Link to provide a debug environment. I suspect,
however, that adapter can be used with other JTAG debuggers such as J-Link,
but that remains to be verified.

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

Information Common to All Configurations
----------------------------------------
Each Clicker2 configuration is maintained in a sub-directory and can be
selected as follow:

cd tools
./configure.sh clicker2-stm32/<subdir>
cd -
. ./setenv.sh

Before sourcing the setenv.sh file above, you should examine it and
perform edits as necessary so that TOOLCHAIN_BIN is the correct path
to the directory than holds your toolchain binaries.

And then build NuttX by simply typing the following. At the conclusion of
the make, the nuttx binary will reside in an ELF file called, simply, nuttx.

make oldconfig
make

The <subdir> that is provided above as an argument to the tools/configure.sh
must be is one of the following.

NOTES:

1. These configurations use the mconf-based configuration tool. To
change any of these configurations 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. Unless stated otherwise, all configurations generate console
output on USART3, channel 0) as described above under "Serial
Console". The relevant configuration settings are listed below:

CONFIG_STM32_USART3=y
CONFIG_STM32_USART3_SERIALDRIVER=y
CONFIG_STM32_USART=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

3. All of these configurations are set up to build under Linux using the
"GNU Tools for ARM Embedded Processors" that is maintained by ARM
(unless stated otherwise in the description of the configuration).

https://launchpad.net/gcc-arm-embedded

That toolchain selection can easily be reconfigured using
'make menuconfig'. Here are the relevant current settings:

Build Setup:
CONFIG_HOST_LINUX =y : Linux environment

System Type -> Toolchain:
CONFIG_ARMV7M_TOOLCHAIN_GNU_EABIL=y : GNU ARM EABI toolchain

Configuration sub-directories
-----------------------------

nsh:

Configures the NuttShell (nsh) located at examples/nsh. This
configuration is focused on low level, command-line driver testing. It
has no network.

NOTES:

1. Support for NSH built-in applications is provided:

Binary Formats:
CONFIG_BUILTIN=y : Enable support for built-in programs

Application Configuration:
CONFIG_NSH_BUILTIN_APPS=y : Enable starting apps from NSH command line

No built applications are enabled in the base configuration, however.

2. C++ support for applications is enabled:

CONFIG_HAVE_CXX=y
CONFIG_HAVE_CXXINITIALIZE=y
CONFIG_EXAMPLES_NSH_CXXINITIALIZE=y