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DDS Module

drawing

The DDS (direct digitzal synthezier) module outputs a continuous sine or triangle wave, with frequency and amplitude modulated by the state machine, a separate Bpod module or both in parallel.

Specs:

  • Arduino-compatible 96MHz ARM Cortex M4 processor (Teensy 3.2)
  • Direct digital synthesis IC (DDS) - AD9834.
    • Driven by 10MHz oscillator, anticipating output frequencies between 1 and 100kHz
  • 12 bit digital amplitude control with an external DAC IC: AD5620
    • Output amplitude from 150mV to 650mV peak-to-peak
  • 1 Bpod state machine port.
  • 1 Bpod module port (most often used for streaming digital inputs, with configurable mapping to frequency outputs).
  • BNC output connector
  • Module can optionally derive its power supply from pocket state machine (using an on-board jumper).

Note: This module loosely implements Analog Devices Circuit Note CN0156 for amplitude control. The output channel is directly driven by the DDS IC, resulting in a DC offset that varies slightly with the amplitude setting. See the amplitude adjustment section in the MATLAB plugin documentation for more info.

Firmware for the DDS module is available here.

Bill of Materials