ardupilot/libraries/AP_HAL_FLYMAPLE/FlymaplePortingNotes.txt

2013-09-23

These notes describe the steps take to port ArduPilot to the Flymaple platform
http://www.open-drone.org/flymaple

Flymaple has an ARM based Cortex-3 STM32F103RE, 72MHz processor with 10DOF builtin sensors


Implementation

Unlike the Arduino versions of ArduPlane, the Flymaple port uses portions of
the libmaple library, including the stm32f1 core and some other libaries like
Wire, HardwareTimer, HArdwareSPI etc.

Most of the changes are confined to new directory libraries/AP_HAL_FLYMAPLE
which contains the Flymaple specific code. All the HAL modules have
been ported, sometimes based on HAL_AVR, sometimes HAL_PX4:
AnalogIn
AnalogSource
Console
GPIO
I2CDriver
RCInput
RCOoutput
Scheduler
Semaphores
SPIDriver
Storage
UARTDriver
Utility

The implementation of Storage uses EEPROM emulation code that uses 2 pages of
Flymaple FLASH ROM as EEPROM. It was copied from
AeroQuad_v3.2 to libraries/AP_HAL_FLYMAPLE/utility and slightly modified:
libraries/AP_HAL_FLYMAPLE/utility/EEPROM.*
libraries/AP_HAL_FLYMAPLE/utility/flash_stm32.*

Unlike other HAL ports, the namespace for Flymaple defined in
AP_HAL_FLYMAPLE_Namespace.h has a more extensive name: 'AP_HAL_FLYMAPLE_NS' else
get complaints from gcc 4.4.1 caused by collisions with other class names.

New board makefile mk/board/flymaple.mk, plus some other minor changes in
mk/*.mk

In other parts of the ArduPlane tree, the changes have been #ifdefed for
Flymaple except:

- ArduPlane/compat.pde
All the wiring compatibility functions have been inline-d, else get
contamination of the namespace at link time (multiple definitions of delay()
etc)

- libraries/AP_Compass/AP_Compass_HMC5843.cpp
- libraries/AP_Compass/Compass.h
- libraries/AP_Baro/AP_Baro_BMP085.cpp
Minor changes to raw data fetches to make them 32bit compatible. Should not
affect other platforms.

Some other minor edits to eliminate compiler warnings

Resource usage
Resources on the Flymaple board have been allocated by the HAL:

Pins
0	GPS Rx in
6	Receiver PPM in
7	GCS Rx in
8	GCS Tx out
15	3.3V board VCC analog in
16	Airspeed analog in (if available)
19	Battery current analog in (if available)
20	Battery voltage analog in (on-board divider connected to board VIN)

Timers
SysTick	100Hz normal timers
1	RCInput
2	Failsafe timer
3,4	RCOut
8	not used

Installation on Linux

Tested with:
libmaple https://github.com/leaflabs/libmaple http://leaflabs.com/docs/unix-toolchain.html
arm-none-eabi-g++ toolchain, version 4.4.1
on OpenSuSE 12.3
Mission Planner 1.2.78

You need a number of additional resources to build ArduPlane for Flymaple. I
have assumed that you will install them in your home directory, but they can really
go anywhere provided you make the appropriate changes

cd ~
git clone https://github.com/leaflabs/libmaple.git
cd libmaple
wget http://static.leaflabs.com/pub/codesourcery/gcc-arm-none-eabi-latest-linux32.tar.gz
tar xvzf gcc-arm-none-eabi-latest-linux32.tar.gz
export PATH=$PATH:~/libmaple/arm/bin

edit ArduPlane/config.mk to be something like:
#config.mk START
# Select maple_RET6 for Flymaple
BOARD = maple_RET6
# HAL_BOARD determines default HAL target.
HAL_BOARD ?= HAL_BOARD_FLYMAPLE
# The communication port used to communicate with the Flymaple
PORT = /dev/ttyACM0
# You must provide the path to the libmaple library directory:
LIBMAPLE_PATH = $(HOME)/libmaple
# Also, the ARM compiler tools MUST be in your current PATH
#config.mk END

Remaining issues:

1. For reasons I do not yet understand, the magnetic heading reported by
ArduPlance is 90 degrees away from what I think it should be.
The sensors on the Flymaple are all aligned with the nominal X, Y and Z axes
collinear. Pitch and roll axes point to the _corners_ of the board, not the
flat sides as might be considered normal for a sensor board.
Orientation is set to NONE, and yes, the reading of compass sensor registers
is in teh right order for the HMC5883.

2. Many alignment warnings emitted by the compiler from libraries/GCS_MAVLink
protocol.h eg:
mnt/disk2/src/ArduPlane-2.74b/libraries/GCS_MAVLink/include/mavlink/v1.0/ardupilotmega/../protocol.h: In function 'uint16_t _MAV_RETURN_uint16_t(const mavlink_message_t*, uint8_t)':
/mnt/disk2/src/ArduPlane-2.74b/libraries/GCS_MAVLink/include/mavlink/v1.0/ardupilotmega/../protocol.h:267: warning: cast from 'const char*' to 'const uint16_t*' increases required alignment of target type