Brontekst bekijken van STM32

  {{Project
   |Name=STM32
   |Picture=HTB1PemDJpXXXXXHXpXXq6xXFXXXM.jpg
   |Omschrijving=STM32 setup guide
   |Status=Completed
   |Contact=bertrik
  }}

== Introduction ==
[[File:bluepill.jpg|thumb|right]]
This page is about inexpensive microcontroller boards containing an STM32 processor and how to get them to work.

You can find these boards on AliExpress for less than €2,- if you search for "stm32f103c8t6".
Yet they have nice specifications, see also http://www.st.com/en/microcontrollers/stm32f103c8.html 

To name a few:
* 32-bit ARM Cortex-M3 processor running at up to 72 MHz
* 128 kB flash memory, 20 kB SRAM
* USB and CAN controllers
* 32 kHz crystal for RTC
* dual 1 us A/D converter, DMA controller
* the usual stuff like SPI, UART, I2C

They are even Arduino compatible, see:
* [http://www.stm32duino.com/ Arduino for STM32]
* [http://grauonline.de/wordpress/?page_id=1004 Arduino goes STM32], a quick tutorial
* [https://github.com/rogerclarkmelbourne/Arduino_STM32 Arduino STM32 page of Roger Clark]

[http://www.oddwires.com/blog/using-a-generic-stm32-board-with-arduino Another, very similar, guide to getting started with STM32 and Arduino].

There are several ways to program an STM32:
* serial: using a built-in serial port bootloader, you need a USB-serial converter for this and you need to move some jumpers each time
* stlink: using an ST-LINK programmer and 4 wires, clones can be found very cheaply on AliExpress (about E2,-)
* stm32duino USB bootloader: after installing the bootloader once (using the serial method), you can rewrite a new program over USB, you just need a USB micro cable 

I like the STM32duino bootloader method.
This way, you need to wire up a USB/serial conversion board and set/reset jumpers only once for bootloader installation and from that point on you can program the board over USB.

== Setting up the tool chain ==
This describes the steps I did to get a "blue pill" board to work on Debian Jessie.

=== Linux specific ===
Some things you need to do on a system level:
* the usual stuff to add your user to the 'dialout' group so you have permission to access the serial port (log out and log in after this)
  sudo adduser <username> dialout
* uninstall the 'modemmanager' package, it interferes with the serial port device created by the STM32duino bootloader
  sudo apt autoremove modemmanager
* install the 32-bit libraries if you're on a 64-bit OS but using the 32-bit binaries (stmflash etc.)
  sudo apt install libc6-i386

=== Arduino IDE ===
Steps to set up the IDE:
* get and install the latest Arduino IDE from [https://www.arduino.cc/en/Main/Software here].
* under menu Tools / Board / Board Manager, search for "zero" and install the Arduino Zero toolchain
* get the Arduino_STM32 source code, for example, run in the console:
<pre>
cd ~/code
mkdir stm32
cd stm32
git clone https://github.com/rogerclarkmelbourne/Arduino_STM32
</pre>
* create a symlink to the Arduino_STM32 source tree in your ~/Arduino/hardware directory, for example:
<pre>
cd ~/Arduino/hardware
ln -s ~/code/stm32/Arduino_STM32 .
</pre>
* restart the Arduino IDE.

=== Platform IO ===
Platformio allows you to build/upload/monitor Arduino programs without using the Arduino IDE (and more).
All settings (which target, which libraries, etc) are stored in a platformio.ini file (instead of existing only as selections in the Arduino IDE).

Below is an example platformio configuration for a blue pill with the USB bootloader.
Save this to a file named platformio.ini in the directory where the .ino file is.
You can build the binary with 'pio run', upload it with 'pio run -t upload' and interact with your sketch over the serial port with 'pio device monitor'.

<pre>
[platformio]
src_dir = .

[env:default]
platform = ststm32
board = genericSTM32F103C8
framework = arduino
upload_protocol = dfu
</pre>

Note: don't use 'bluepill_f103c8' as board, it is not compatible with the stm32duino bootloader!

== Hardware ==
[[File:bluepill_pinout.png|right|thumb]]

The hardware I'm using, is the [http://wiki.stm32duino.com/index.php?title=Blue_Pill blue pill], I soldered on the headers for easy plugging with dupont-wire.

=== Pinout LQFP48 ===
[[File:stm32_lqfp48_pinout.png|right|thumb]]
[http://www.olliw.eu/ OlliW] made a nice pinout diagram of the STM32 in the LQFP48 package, which I'm reproducing here (converted from JPG to PNG).

=== Flashing the USB bootloader ===
The USB bootloader makes it easy/fast to upload new software into the board over USB.

You need a USB-serial converter for this.

Wire it up as follows:
* converter 5V -> board 5V
* converter GND -> board GND
* converter RXD -> board A9
* converter TXD -> board A10


For the blue pill the steps to install the bootloader are as follows:
* clone the git archive containing the STM32 bootloaders:
  git clone https://github.com/rogerclarkmelbourne/STM32duino-bootloader
* cd into the directory Arduino_STM32/tools/linux/stm32flash
* set the BOOT0 jumper to the "1" position and the BOOT1 jumper to the "0" position, then push the reset button.
* disable the flash-read protection:
  ./stm32flash /dev/ttyUSB0 -k
* flash the bootloader:
  ./stm32flash -w ~/code/stm32/STM32duino-bootloader/binaries/generic_boot20_pc13.bin -v -g 0x0 /dev/ttyUSB0
* return both BOOT jumpers to the "0" position.

== Software ==
To load your application using the Arduino IDE:
* in the Arduino IDE, under menu Tools / Board, select "Generic STM32F103C Series"
* in the Arduino IDE, under menu Tools / Upload Method, select "STM32duino bootloader"
* use the following program to blink the on-board LED:
<pre>
#define pinLED PC13

void setup() {
  pinMode(pinLED, OUTPUT);
}

void loop() {
  digitalWrite(pinLED, HIGH);
  delay(200);
  digitalWrite(pinLED, LOW);
  delay(100);
}
</pre>
* ctrl-U to upload it to the board, the program will start automatically

=== A/D converter ===
STM32 has built-in A/D converters, but how can you effectively use them?

Useful references:
* ~/.platformio/packages/framework-arduinoststm32-maple/STM32F1/libraries/STM32ADC/src is a kind of wrapper around utility/util_adc.h 
* https://deepbluembedded.com/stm32-adc-tutorial-complete-guide-with-examples/

= Future work =
Actually build something with an STM32!

Ideas:
* a LoRaWAN node for The-Things-Network
* a bat call recorder, this thing is faster and has more memory than the LPC2148 in my previous bat call recorder prototype

Investigate the [https://github.com/blacksphere/blackmagic/wiki Blackmagic] debugging firmware.
This should allow you to debug your applications (e.g. step through code in an IDE such as eclipse).
See also:
* https://nuft.github.io/arm/2015/08/24/blackmagic-stlink.html
* https://medium.com/@paramaggarwal/converting-an-stm32f103-board-to-a-black-magic-probe-c013cf2cc38c#.h2md3y5hl