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=Waveform generator=
The waveform generator provides the reference sinusoidal signals for each emitter coil of the field generator. The generator comprises of a single Analog Devices [http://www.analog.com/media/en/technical-documentation/data-sheets/AD9833.pdf AD9833] programmable integrated circuit which provides a reference sinewave at a desired frequency. The IC is programmed over the SPI bus using a microcontroller.
==Programming the AD9833==
The AD9833 synthesises the reference sine waves for each emitter coil. The integrated circuit is programmed over the serial peripheral interface (SPI) using a microcontroller. On powering up the IC needs to be configured to output the required frequency. The AD9833 contains a set of registers which can be written over the SPI interface.
The desired frequency register value (denoted 'FREQREG' in the datasheet) can be found using the following formula:
