Hi Scott
The waveform generator actually requires different firmware from v2.0.1: look in /PulsePal/Waveform Generator/Arduino/
v2.0.1 is firmware that supports a proper object oriented interface for Pulse Pal's parametric pulse train functions, in /MATLAB_GEN2/.
Your need sounds like a perfect case for WaveGen's customWaveform function. The example code below (untested) should do the job:
Wave = [ones(1,2000)*5 4.98:-0.025:0]; % Generate waveform (sampled at 1kHz)
P = PulsePalWaveGen('COM3'); % Create WaveGen object (replace COM3 with your actual serial port)
P.customWaveform = Wave; % Upload the waveform
P.customWaveformSF = 1000; % Set sampling rate to 1kHz
P.waveform = 'custom'; % Tell WaveGen to use a custom waveform (instead of the default parametric function generator)
% By default, output Ch1 will respond to a TTL on trigger Ch1.
% You can also soft-trigger to test the playback with:
P.trigger;
Depending on how evenly you want the down-ramp to be, you can increase the sampling rate to 10kHz - the first line would then use [ones(1,20000)*5 4.998:-0.0025:0]
-Josh