ADAHRS

This board provides the Air Data and Attitude data. The Attitude data is provided by another board that I purchased from Polulu called the 'UM6'. This sensor has accelerometers, gyroscopes and a magnetic sensor. It is then processed by an ARM processor with a Kalman Filter to provide the Attitude data. It is mounted on top of the board that I make. It communicates with the 8-bit processor using SPI.

I am using an Atmel AVR AT90CAN32 8-bit SOC for the CAN controller. The CAN transceiver is a Microchip MCP2551. The CAN input/output is electrically isolated from the rest of the board in case of lightning or radio-frequency induced noise on the CAN bus wires. This is done with a ADuM1301 optical isolator. The board also has 5V and 3.3V power taken from the 12V power provided by the input wiring.

The Air Data is provided by 3 separate barometric sensors (BMP-085) that are wired to the board using ribbon cable. They (will) be encased in plastic tubes with tubing fittings so the can be connected to the pitot-static system. The breakout boards are from Sparkfun. The breakout boards communicate with the 8-bit processor using the I2C bus. There is an I2C switch in the circuit, as these chips don't allow the I2C addresses to be changed, causing interference on the I2C bus. The datasheet recommends holding chips not communicating with the master device in reset, but this slows down the data collection as there is some settle time after taking the device out of reset, so I added the switch, which will allow the particular pressure device to be selected by the 8-bit processor for data retrieval and device command operations.

Completed ADAHRS 1.0 Board without UM6
First board without UM6 installed.Full Size

Schematics

Power Schematics
Full Size

CPU Schematics
Full Size

UM6 Schematics
Full Size

CAN Schematics
Full Size

Air Data Schematics
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Circuit Board

ADAHRS circuit board
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