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This page has deprecated and moved to the new documentation framework of the main Bitcraze website. Please go to [[https://www.bitcraze.io/documentation/system/]]
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====== Making your first Deck driver ======

This howto is going to describe step-by-step how to make and flash your first
Crazyflie 2.X deck driver. See the deck [[doc:crazyflie:api:firmware:deck|api documentation page]] for more information about the code.

===== Development environment =====

You should have the [[https://github.com/bitcraze/crazyflie-firmware|crazyflie-firmware]] and [[https://github.com/bitcraze/crazyflie-clients-python|crazyflie-clients-python]] cloned in the same folder. If you are using the [[projects:virtualmachine:index|Bitcraze VM]] this is already the case.

The Crazyflie firmware should be on Master branch.

For the rest of the howto you will work in the crazyflie-firmware project.

===== Writing the driver =====

Deck drivers are in the deck/driver/src folder. Create this file named hello.c in the deck/driver/src folder:

<code c hello.c>
#define DEBUG_MODULE "HelloDeck"
#include "debug.h"

#include "deck.h"


static void helloInit()
{
  DEBUG_PRINT("Hello Crazyflie 2.0 deck world!\n");
}

static bool helloTest()
{
  DEBUG_PRINT("Hello test passed!\n");
  return true;
}

static const DeckDriver helloDriver = {
  .name = "myHello",
  .init = helloInit,
  .test = helloTest,
};

DECK_DRIVER(helloDriver);
</code>

===== Adding the driver to the build =====

Add this to the Makefile, after the line '# Decks':

<code make>
PROJ_OBJ += hello.o
</code>

===== Enabling the driver =====

Decks can have a memory that contains its name. In our case the hello driver would be initialised only when a deck identified as "myHello" is installed on the Crazyflie. For development purpose it is possible to force enabling a deck driver with a compile flag. To do so create the file tools/make/config.mk with the content:

<code make config.mk>
CFLAGS += -DDECK_FORCE=myHello

DEBUG=1
</code>

DEBUG=1 allows to get more information from the Crazyflie console when it starts. Debug should not be enabled if you intend to fly the Crazyflie out of the lab (it disables the watchdog).

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//**Note**// Each time you modify config.mk you should recompile the full firmware by cleaning up the build folder with 'make clean'
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===== Compile, flash and run! =====

Now the last step is to compile and flash your new firmware. Launch the following commands in a shell:

<code bash>
crazyflie-firmware$ make
crazyflie-firmware$ make cload
</code>

The output will be similar to the following:

<code bash>
crazyflie-firmware$ make
(...)
  CC    hello.o
(...)
Crazyflie 2.0 build!
Build 44:61f3d878233d (2015.08.1-44) MODIFIED
Version extracted from git
Crazyloader build!
   text	   data	    bss	    dec	    hex	filename
 130660	   1636	  29828	 162124	  2794c	cf2.elf
rm version.c
crazyflie-firmware$ make cload
../crazyflie-clients-python/bin/cfloader flash cf2.bin stm32-fw
Restart the Crazyflie you want to bootload in the next
 10 seconds ...
 done!
Connected to bootloader on Crazyflie 2.0 (version=0x10)
Target info: nrf51 (0xFE)
Flash pages: 232 | Page size: 1024 | Buffer pages: 1 | Start page: 88
144 KBytes of flash available for firmware image.
Target info: stm32 (0xFF)
Flash pages: 1024 | Page size: 1024 | Buffer pages: 10 | Start page: 16
1008 KBytes of flash available for firmware image.

Flashing 1 of 1 to stm32 (fw): 161867 bytes (159 pages) ..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10..........10.........9
Reset in firmware mode ...
$ 
</code>

Now you can connect your Crazyflie with the client and see your driver in the console!

{{ :doc:crazyflie:api:firmware:deck:deckhelloconsole.png |}}