Description

The Direct Digital Synthesis (DDS) module generates a continuous sine or triangle waveform, whose frequency and amplitude can be rapidly updated by either the Bpod state machine or by a separate input module. Waveform parameters can be streamed to the module to shape its output at 10kHz. The module can provide input to an amplified speaker, to generate a rapidly variable auditory stimulus. Example firmware and MATLAB software is provided for a closed loop behavior use case, where an Arduino M0 + Bpod shield reads an analog signal at 10kHz and streams its value to the DDS module. A configurable mapping function on the DDS module converts the analog signal to an output frequency. In this streaming-input configuration, the DDS module can generate behavior events to indicate when its frequency and amplitude parameters cross thresholds or meet other conditions.

Specifications

Compatability

• Requires Bpod v0.7 or newer.

Processor

• ARM Cortex M4: Freescale K20P64M50SF0 as part of the Teensy 3.2 development platform
• 90MHz Clock Speed
• 64KB sRAM
• Programmable using the Arduino language

Inputs

• Bpod State Machine (via RS-485 buffered UART, 1.3Mb/s)
• Second Bpod Module (via RS-485 buffered UART, 1.3Mb/s)
• USB

Outputs

• 1 output channel, driven by a DDS IC: Analog Devices AD9834
• Frequency Range: 1Hz : 100kHz
• Amplitude Range: 0mV : 650mV peak-to-peak
• Note: The signal has a DC offset that varies slightly with the amplitude setting. See the MATLAB plugin documentation section on amplitude adjustment for more info.

Power supply

• Can be derived from a USB A to B-micro cable (included)
• By connecting an onboard jumper, the board can be powered from State Machine r2. In this configuration, a dedicated USB cable is not required.

Material safety

• All parts are RoHS Compliant in our professional builds

Dimensions

• L: 10cm (4")
• W: 7cm (2.25")
• H: 4cm (1.5")