Running NuttX on a less than U$2.00 board

Few months ago I discovered a low cost board powered by STM32F103C8T6 microcontroller.

That board is referenced as “STM32 Minimum System Development Board” or as “BluePill Board”:

http://www.cnx-software.com/2016/05/17/bluepill-is-a-2-arduino-compatible-development-board-based-on-stmicro-stm32-mcu/

http://www.stm32duino.com/viewtopic.php?t=117

I bought that board from Aliexpress for U$1.96:
http://aliexpress.com/item/STM32F103C8T6-ARM-STM32-Minimum-System-Development-Board-Module-ForArduin/32282374854.html

Then when it arrived I got NuttX running on it and submitted a patch to Mr. Greg to add it to NuttX mainline. Now everybody can get NuttX running on it easily.

This tutorial will explain how to do that, first let me list what you will need:
– The STM32F103C8T6 Minimum board;
– A STLinkV2 programmer (or a low cost clone) ;
– A USB/Serial adapter 3.3V compatible (like this one on ebay);
– A USB to MicroUSB cable, like these used to recharge your smartphone;
– A computer running Linux Debian or Ubuntu (it is possible on Windows using Cygwin or Mac OS, but I don’t use these OS).

First step is the instalation of development tools:
1) Install gcc-arm-none-eabi package:

$ sudo apt-get install gcc-arm-none-eabi

2) Compile and install OpenOCD
Note: If your system doesn’t have the development tools and libraries then install these packages listed here: https://acassis.wordpress.com/2013/10/07/quais-pacotes-de-desenvolvimento-instalar-no-linux/

$ git clone http://repo.or.cz/r/openocd.git
$ cd openocd
$ ./bootstrap
$ ./configure --enable-internal-jimtcl --enable-maintainer-mode --disable-werror --disable-shared --enable-stlink --enable-jlink --enable-rlink --enable-vslink --enable-ti-icdi --enable-remote-bitbang --enable-usb-blaster --enable-presto --enable-osbdm

You will see it at end of this process:

libjaylink configuration summary:
 - Package version ................ 0.1.0
 - Library version ................ 0:0:0
 - Installation prefix ............ /usr/local
 - Building on .................... x86_64-pc-linux-gnu
 - Building for ................... x86_64-pc-linux-gnu



OpenOCD configuration summary
--------------------------------------------------
MPSSE mode of FTDI based devices        yes (auto)
Segger J-Link JTAG Programmer           yes
ST-Link JTAG Programmer                 yes
TI ICDI JTAG Programmer                 yes
Keil ULINK JTAG Programmer              yes (auto)
Altera USB-Blaster II Compatible        yes (auto)
Versaloon-Link JTAG Programmer          yes
OSBDM (JTAG only) Programmer            yes (auto)
eStick/opendous JTAG Programmer         yes (auto)
Andes JTAG Programmer                   yes (auto)
USBProg JTAG Programmer                 yes (auto)
Raisonance RLink JTAG Programmer        yes
Olimex ARM-JTAG-EW Programmer           yes (auto)
CMSIS-DAP Compliant Debugger            yes (auto)

Now compile and install it:

$ make
$ sudo make install

Now the next step is download and compiling NuttX:

1) Download the NuttX kernel and its applications:

$ mkdir NuttX
$ cd NuttX
$ git clone https://bitbucket.org/nuttx/nuttx
$ git clone https://bitbucket.org/nuttx/apps
$ git clone https://bitbucket.org/nuttx/tools

2) Compile the Kconfig Frontend needed by NuttX:

$ cd tools/kconfig-frontends
$ ./configure
$ make
$ sudo make install

3) Compile NuttX for stm32f103-minimum board:

$ cd ../..
$ cd nuttx/tools
$ ./configure.sh stm32f103-minimum/nsh
$ make menuconfig

Enter into "Build Setup" menu and confirm that "Build Host Platform" is defined to Linux
Enter in "System Type" -> "Toolchain Selection" and confirm that:
(X) Generic GNU EABI toolchain under Linux

Select <EXIT> and confirm to save everything.

Now you can compile it:

$ make

At end of compilation you will see:

make[2]: Leaving directory '/tmp/NuttX/nuttx/configs/stm32f103-minimum/src'
LD: nuttx
make[1]: Leaving directory '/tmp/NuttX/nuttx/arch/arm/src'
CP: nuttx.bin

3) Flashing the firmware nuttx.bin in the stm32f103-minimum board:
Connect the USB Cable and the STLinkV2 programmer to STM32F103 board this way:

Create a file openocd_stm32f1.cfg with this content:

# Using stlink as SWD programmer
source [find interface/stlink-v2.cfg]

# SWD as transport
transport select hla_swd

# Use STM32F103 target
set WORKAREASIZE 0x4000
source [find target/stm32f103c8t6.cfg]

Execute OpenOCD passing this configuration file:

$ sudo openocd -f openocd_stm32f1.cfg

Open On-Chip Debugger 0.10.0-dev-00300-g89bf96f-dirty (2016-05-20-17:42)
Licensed under GNU GPL v2
adapter speed: 1000 kHz
adapter_nsrst_delay: 100
none separate
Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : clock speed 950 kHz
Info : STLINK v2 JTAG v17 API v2 SWIM v4 VID 0x0483 PID 0x3748
Info : using stlink api v2
Info : Target voltage: 3.297181
Info : stm32f1x.cpu: hardware has 6 breakpoints, 4 watchpoints

Open a new shell terminal and execute:

$ telnet 127.0.0.1 4444

You will be presented with this message:

Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
Open On-Chip Debugger
> 

Now execute this command to store nuttx.bin in the stm32f103 flash memory:

> reset halt

stm32f1x.cpu: target state: halted
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x080003ac msp: 0x20000730

> flash write_image erase nuttx.bin 0x08000000

auto erase enabled
device id = 0x20036410
ignoring flash probed value, using configured bank size
flash size = 128kbytes
stm32f1x.cpu: target state: halted
target halted due to breakpoint, current mode: Thread 
xPSR: 0x61000000 pc: 0x2000003a msp: 0x20000730
wrote 40960 bytes from file nuttx.bin in 2.384699s (16.774 KiB/s)
> 

Finally all you need to do is to connect a USB/Serial and use a Serial Console as Minicom/Picocom/Screen to get access to NuttX terminal .

-------------------------------
|USB/Serial | STM32F103 Board |
-------------------------------
|   RXD     |       A9        |
|   TXD     |      A10        |
|   GND     |       G         |
-------------------------------

Configure Minicom or use your preferred serial program to 115200 8n1 with your USB/Serial adapter, i.e /dev/ttyUSB0. You will get this message after pressing the RESET button:

NuttShell (NSH)
nsh> 

• BrainDamage