[Paparazzi-devel] Alternative options for Booz hardware

[Vassilis V.]

A question to the Booz experts!

I know the there are a few people that are working on offering  
complete Booz hardware kits and I will likely be getting one once they  
become available. However being the impatient guy I am, I would like  
your opinion on a alternative setup based on existing hardware and the  
Booz software.

The idea is basically to use the following hardware in order to put  
together a Booz controlled quadcopter. All hardware is already  
available and the airborne software will be very similar to the  
existing code base with some modifications to handle the new IMU.

- TWOG (or Tiny) board as the main controller
- GPS connected to the TWOG GPS port (if not using a Tiny)
- Xbee modem connected to the telemetry port
- CHR-6d 6DOF Inertial Measurement Unit from http://www.chrobotics.com/CHR6d.php 
 . This is a relatively new board with a lot of nice features, 64MHz  
ARM MCU, open source software, 16 bit ADC, all sensors are flat and  
very small. It has a TTL UART or I2C interface. I am planning to  
connect it to the I2C1 port of the TWOG board.
- HMC5843 3-axis magnetometer from Sparkfun http://www.sparkfun.com/commerce/product_info.php?products_id=9371 
 . It will be connected to I2C1 port together with the IMU.
- 4x TowerPro ESC with modified firmware. These will be connected to  
the I2C0 port of the TWOG board.

I went through the Booz main board schematics and one difference I  
spotted is the level converters on the I2C port. The TowerPro are  
based on a 5V ATMega8 MCU, however I have used this ESC (in PWM mode)  
with a 3.3V MCU with no problems (high-level threshold for the ATMega  
is 3V). The accels and gyros used in the CHR-6d IMU look decent and  
the additional processing power on the board may allow for some more  
advanced signal processing if needed.

Do you see any major issues with the above setup? I know I will have  
to make some modifications on the code and I am fine with that (I am  
doing this for fun after all :-)), I just want to make sure that I am  
not missing anything major. I already have most of the hardware  
including the quadcopter frame.

Thanks for any feedback and sorry for the long post,
Vassilis

P.S. The above setup could also be used on a fixed wing (using a  
slightly modified version of the Paparazzi code to support the IMU),  
but this is another project!