README
======
This README discusses issues unique to NuttX configurations for the
STM32F103C8T6 Minimum System Development Board for ARM Microcontroller.
This board is available from several vendors on the net, and may
be sold under different names or no name at all. It is based on a
STM32F103C8T6 and has a DIP-40 form-factor.
There are two versions of very similar boards: One is red and one is
blue. See http://www.stm32duino.com/viewtopic.php?f=28&t=117
The Red Board:
Good things about the red board:
- 1.5k pull up resistor on the PA12 pin (USB D+) which you can
programatically drag down for automated USB reset.
- large power capacitors and LDO power.
Problems with the red board:
- Silk screen is barely readable, the text is chopped off on some of
the pins
- USB connector only has two anchor points and it is directly soldered
on the surface
- Small reset button with hardly any resistance
The Blue Board:
Good things about the blue board:
- Four soldered anchor point on the USB connector. What you can't tell
from this picture is that there is a notch in the pcb board and the USB
connector sits down inside it some. This provides some lateral stability
that takes some of the stress off the solder points.
- It has nice clear readable silkscreen printing.
- It also a larger reset button.
Problems with the blue board:
- Probably won't work as a USB device if it has a 10k pull-up on PA12. You
have to check the pull up on PA12 (USB D+). If it has a 10k pull-up
resistor, you will need to replace it with a 1.5k one to use the native
USB.
- Puny voltage regulator probably 100mA.
A schematic for the blue board is available here:
http://www.stm32duino.com/download/file.php?id=276
Both Boards:
Nice features common to both:
- SWD pins broken out and easily connected (VCC, GND, SWDIO, SWCLK)
- USB 5V is broken out with easy access.
- User LED on PC13
- Power LED
- You can probably use more flash (128k) than officially documented for
the chip (stm32f103c8t6 64k), I was able to load 115k of flash on mine
and it seemed to work.
Problems with both boards:
- No preloaded bootloader * to me this isn't really a problem as the
entire 64k of flash is available for use
- No user button
This is the board pinout based on its form-factor for the Blue board:
USB
___
-----/ _ \-----
|B12 GND|
|B13 GND|
|B14 3.3V|
|B15 RST|
|A8 B11|
|A9 B10|
|A10 B1|
|A11 B0|
|A12 A7|
|A15 A6|
|B3 A5|
|B4 A4|
|B5 A3|
|B6 A2|
|B7 A1|
|B8 A0|
|B9 C15|
|5V C14|
|GND C13|
|3.3V VB|
|_____________|
Contents
========
- LEDs
- UARTs
- Timer Inputs/Outputs
- Using 128KiB of Flash instead of 64KiB
- STM32F103 Minimum - specific Configuration Options
- Configurations
LEDs
====
The STM32F103 Minimum board has only one software controllable LED.
This LED can be used by the board port when CONFIG_ARCH_LEDS option is
enabled.
If enabled the LED is simply turned on when the board boots
succesfully, and is blinking on panic / assertion failed.
UARTs
=====
UART/USART PINS
---------------
USART1
RX PA10
TX PA9
USART2
CK PA4
CTS PA0
RTS PA1
RX PA3
TX PA2
USART3
CK PB12
CTS PB13
RTS PB14
RX PB11
TX PB10
Default USART/UART Configuration
--------------------------------
USART1 (RX & TX only) is available through pins PA9 (TX) and PA10 (RX).
Timer Inputs/Outputs
====================
TIM1
CH1 PA8
CH2 PA9*
CH3 PA10*
CH4 PA11*
TIM2
CH1 PA0*, PA15, PA5
CH2 PA1, PB3
CH3 PA2, PB10*
CH4 PA3, PB11
TIM3
CH1 PA6, PB4
CH2 PA7, PB5*
CH3 PB0
CH4 PB1*
TIM4
CH1 PB6*
CH2 PB7
CH3 PB8
CH4 PB9*
* Indicates pins that have other on-board functions and should be used only
with care (See board datasheet).
Using 128KiB of Flash instead of 64KiB
======================================
Some people figured out that the STM32F103C8T6 has 128KiB of internal memory
instead of 64KiB as documented in the datasheet and reported by its internal
register.
In order to enable 128KiB you need modify the linker script to reflect this
new size. Open the configs/stm32f103-minimum/scripts/ld.script and replace:
flash (rx) : ORIGIN = 0x08000000, LENGTH = 64K
with
flash (rx) : ORIGIN = 0x08000000, LENGTH = 128K
Enable many NuttX features (ie. many filesystems and applications) to get a
large binary image with more than 64K.
We will use OpenOCD to write the firmware in the STM32F103C8T6 Flash. Use a
up to dated OpenOCD version (ie. openocd-0.9).
You will need to create a copy of original openocd/scripts/target/stm32f1x.cfg
to openocd/scripts/target/stm32f103c8t6.cfg and edit the later file replacing:
flash bank $_FLASHNAME stm32f1x 0x08000000 0 0 0 $_TARGETNAME
with
flash bank $_FLASHNAME stm32f1x 0x08000000 0x20000 0 0 $_TARGETNAME
We will use OpenOCD with STLink-V2 programmer, but it will work with other
programmers (JLink, Versaloon, or some based on FTDI FT232, etc).
Open a terminal and execute:
$ sudo openocd -f interface/stlink-v2.cfg -f target/stm32f103c8t6.cfg
Now in other terminal execute:
$ telnet localhost 4444
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Open On-Chip Debugger
> reset halt
stm32f1x.cpu: target state: halted
target halted due to debug-request, current mode: Thread
xPSR: 0x01000000 pc: 0x080003ac msp: 0x20000d78
> 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: 0x20000d78
wrote 92160 bytes from file nuttx.bin in 4.942194s (18.211 KiB/s)
> reset run
> exit
Now NuttX should start normally.
STM32F103 Minimum - 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_CORTEXM3=y
CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory
CONFIG_ARCH_CHIP=stm32
CONFIG_ARCH_CHIP_name - For use in C code to identify the exact
chip:
CONFIG_ARCH_CHIP_STM32F103C8=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=stm32f103-minium
CONFIG_ARCH_BOARD_name - For use in C code
CONFIG_ARCH_BOARD_STM32_MINIMUM=y
CONFIG_ARCH_LOOPSPERMSEC - Must be calibrated for correct operation
of delay loops
CONFIG_ENDIAN_BIG - define if big endian (default is little
endian)
CONFIG_RAM_SIZE - Describes the installed DRAM (SRAM in this case):
CONFIG_RAM_SIZE=20480 (20Kb)
CONFIG_RAM_START - The start address of installed DRAM
CONFIG_RAM_START=0x20000000
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_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 calibratre
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:
AHB
---
CONFIG_STM32_CRC
CONFIG_STM32_BKPSRAM
APB1
----
CONFIG_STM32_TIM2
CONFIG_STM32_TIM3
CONFIG_STM32_TIM4
CONFIG_STM32_WWDG
CONFIG_STM32_IWDG
CONFIG_STM32_SPI2
CONFIG_STM32_USART2
CONFIG_STM32_USART3
CONFIG_STM32_I2C1
CONFIG_STM32_I2C2
CONFIG_STM32_CAN1
CONFIG_STM32_PWR -- Required for RTC
APB2
----
CONFIG_STM32_TIM1
CONFIG_STM32_USART1
CONFIG_STM32_ADC1
CONFIG_STM32_ADC2
CONFIG_STM32_SPI1
Timer devices may be used for different purposes. One special purpose is
to generate modulated outputs for such things as motor control. If CONFIG_STM32_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 or ADC conversion.
Note that ADC require two definitions: Not only do you have
to assign the timer (n) for used by the ADC, but then you also have to
configure which ADC (m) it is assigned to.
CONFIG_STM32_TIMn_PWM Reserve timer n for use by PWM, n=1,..,14
CONFIG_STM32_TIMn_ADC Reserve timer n for use by ADC, n=1,..,14
CONFIG_STM32_TIMn_ADCm Reserve timer n to trigger ADCm, n=1,..,14, m=1,..,3
For each timer that is enabled for PWM usage, we need the following additional
configuration settings:
CONFIG_STM32_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.
JTAG Enable settings (by default only SW-DP is enabled):
CONFIG_STM32_JTAG_FULL_ENABLE - Enables full SWJ (JTAG-DP + SW-DP)
CONFIG_STM32_JTAG_NOJNTRST_ENABLE - Enables full SWJ (JTAG-DP + SW-DP)
but without JNTRST.
CONFIG_STM32_JTAG_SW_ENABLE - Set JTAG-DP disabled and SW-DP enabled
STM32F103 Minimum specific device driver settings
CONFIG_U[S]ARTn_SERIAL_CONSOLE - selects the USARTn (n=1,2,3)
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
STM32F103 Minimum CAN Configuration
CONFIG_CAN - Enables CAN support (one or both of CONFIG_STM32_CAN1 or
CONFIG_STM32_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_STM32_CAN1 is defined.
CONFIG_CAN2_BAUD - CAN1 BAUD rate. Required if CONFIG_STM32_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.
STM32F103 Minimum SPI Configuration
CONFIG_STM32_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_STM32_SPI_DMA - Use DMA to improve SPI transfer performance.
Cannot be used with CONFIG_STM32_SPI_INTERRUPT.
Configurations
==============
Each STM32F103 Minimum configuration is maintained in a sub-directory and
can be selected as follow:
cd tools
./configure.sh STM32F103 Minimum/<subdir>
cd -
. ./setenv.sh
If this is a Windows native build, then configure.bat should be used
instead of configure.sh:
configure.bat STM32F103-Minimum\<subdir>
Where <subdir> is one of the following:
minnsh:
------
This is a experiment to see just how small we can get a usable NSH
configuration. This configuration has far fewer features than the nsh
configuration but is also a fraction of the size.
This minnsh configuration is a "proof-of-concept" and not very usable in
its current state. This configuration was created by disabling
everything possible INCLUDING file system support. Without file system
support, NuttX is pretty much crippled. Here are some of the
consequences of disabling the file system:
- All features that depend on the file system are lost: device drivers,
mountpoints, message queues, named semaphores.
- Without device drivers, you cannot interact with the RTOS using POSIX
interfaces. You would have to work with NuttX as with those other
tiny RTOSs: As a scheduler and a callable hardare abstraction layer
(HAL).
- You cannot use any of the NuttX upper half device drivers since they
depend on the pseudo-file system and device nodes. You can, of
course, continue to use the lower half drivers either directly. Or,
perhaps, you could write some custom minnsh upper half drivers that
do not depend on a file system and expose a HAL interface.
There is a special version of readline() the NSH uses when there is no
file system. It uses a special up_putc() to write data to the console
and a special function up_getc() to read data from the console.
- The current up_getc() implementationsa are a kludge. They are
analogous to the up_putc() implementations: They directly poll the
hardware for serial availability, locking up all lower priority tasks
in the entire system while they poll. So a version of NSH that uses
up_getc() essentially blocks the system until a character is received.
This, of course, could be fixed by creating a special, upper half
implementation of the interrupt-driven serial lower half (like
stm32_serial) that just supports single character console I/O
(perhaps called up_putc and up_getc?). The NSH could wait for serial
input without blocking the system. But then that would increase the
footprint too.
So although the minnsh configurations are a good starting point for
making things small, they not are really very practical. Why might
you want a NuttX minnsh solution? Perhaps you have software that runs
on a family of chips including some very tiny MCUs. Then perhaps having
the RTOS compatibility would justify the loss of functionality?
STATUS:
2016-06-03: Using that config I got this:
$ ls -l nuttx.bin
-rwxr-xr-x 1 alan alan 12543 Jun 3 17:58 nuttx.bin
$ arm-none-eabi-size nuttx
text data bss dec hex filename
12542 1 816 13359 342f nuttx
And this is free command from NuttX shell:
NuttShell (NSH)
nsh> free
total used free largest
Mem: 18624 2328 16296 16296
nsh>
2016-06-07: As another experiment, I tried enabling just (1) the file
system, (2) the console device, and (3) the upper half serial driver in
the minnsh configuration. With these changes, NSH should behave better
and we preserve the device driver interface. I made the following
configuration changes:
Enable the file system:
CONFIG_NFILE_DESCRIPTORS=5
CONFIG_NFILE_STREAMS=5
Enable the console device:
CONFIG_DEV_CONSOLE=y
Disable most new NSH commands. Some like 'ls' are really mandatory
with a file system:
CONFIG_NSH_DISABLE_xxx=y
Enable the upper half serial driver:
CONFIG_SERIAL=y
CONFIG_STANDARD_SERIAL=y
Enable the USART1 serial driver:
CONFIG_STM32_USART1=y
CONFIG_STM32_USART1_SERIALDRIVER=y
CONFIG_USART1_SERIAL_CONSOLE=y
CONFIG_USART1_2STOP=0
CONFIG_USART1_BAUD=115200
CONFIG_USART1_BITS=8
CONFIG_USART1_PARITY=0
CONFIG_USART1_RXBUFSIZE=16
CONFIG_USART1_TXBUFSIZE=16
The resulting code was bigger as expected:
$ arm-none-eabi-size nuttx
text data bss dec hex filename
19853 88 876 20817 5151 nuttx
I am sure that other things that could be disabled were also drawn into
the build, so perhaps this could be reduced. This amounts to a size
increase of around 7KB.
One major part of this size increase is due to the addition of the NSH
'ls' command. Now, if I disable the 'ls' command, I get:
$ arm-none-eabi-size nuttx
text data bss dec hex filename
17804 80 864 18748 493c nuttx
Or an increase of only 5.1 KB. This, of course, not only excludes the
'ls' command logic, but also the things that were drawn into the link
when 'ls' was enabled: opendir(), readdir(), closedir(), stat(), and
probably other things.
So I think we can say that the cost of the file system and true serial
console device was about 5 KB (primarily OS support) and the cost of
the NSH 'ls' command (including OS support) is about 2KB.
2016-06-21: Just checking the size after some big system changes: The
size of the base configuration has actually dropped by a few bytes:
$ arm-none-eabi-size nuttx
text data bss dec hex filename
12526 4 816 13346 3422 nuttx
nsh:
---
Configures the NuttShell (nsh) located at apps/examples/nsh. This
configuration enables a console on UART1. Support for
builtin applications is enabled, but in the base configuration no
builtin applications are selected.
usbnsh:
-------
This is another NSH example. If differs from other 'nsh' configurations
in that this configurations uses a USB serial device for console I/O.
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 CodeSourcery toolchain
for Windows and builds under Cygwin (or probably MSYS). That
can easily be reconfigured, of course.
CONFIG_HOST_WINDOWS=y : Builds under Windows
CONFIG_WINDOWS_CYGWIN=y : Using Cygwin
CONFIG_ARMV7M_TOOLCHAIN_CODESOURCERYW=y : CodeSourcery for Windows
3. This configuration does have UART2 output enabled and set up as
the system logging device:
CONFIG_SYSLOG_CHAR=y : Use a character device for system logging
CONFIG_SYSLOG_DEVPATH="/dev/ttyS0" : UART2 will be /dev/ttyS0
However, there is nothing to generate SYLOG output in the default
configuration so nothing should appear on UART2 unless you enable
some debug output or enable the USB monitor.
4. Enabling USB monitor SYSLOG output. If tracing is enabled, the USB
device will save encoded trace output in in-memory buffer; if the
USB monitor is enabled, that trace buffer will be periodically
emptied and dumped to the system loggin device (UART2 in this
configuraion):
CONFIG_USBDEV_TRACE=y : Enable USB trace feature
CONFIG_USBDEV_TRACE_NRECORDS=128 : Buffer 128 records in memory
CONFIG_NSH_USBDEV_TRACE=n : No builtin tracing from NSH
CONFIG_NSH_ARCHINIT=y : Automatically start the USB monitor
CONFIG_USBMONITOR=y : Enable the USB monitor daemon
CONFIG_USBMONITOR_STACKSIZE=2048 : USB monitor daemon stack size
CONFIG_USBMONITOR_PRIORITY=50 : USB monitor daemon priority
CONFIG_USBMONITOR_INTERVAL=2 : Dump trace data every 2 seconds
CONFIG_USBMONITOR_TRACEINIT=y : Enable TRACE output
CONFIG_USBMONITOR_TRACECLASS=y
CONFIG_USBMONITOR_TRACETRANSFERS=y
CONFIG_USBMONITOR_TRACECONTROLLER=y
CONFIG_USBMONITOR_TRACEINTERRUPTS=y
5. By default, this project assumes that you are *NOT* using the DFU
bootloader.
Using the Prolifics PL2303 Emulation
------------------------------------
You could also use the non-standard PL2303 serial device instead of
the standard CDC/ACM serial device by changing:
CONFIG_CDCACM=y : Disable the CDC/ACM serial device class
CONFIG_CDCACM_CONSOLE=y : The CDC/ACM serial device is NOT the console
CONFIG_PL2303=y : The Prolifics PL2303 emulation is enabled
CONFIG_PL2303_CONSOLE=y : The PL2303 serial device is the console
