Dear Josh,

When using BpodWavePlayer, we notice that when a wave is playing in loop mode (in one channel) and we try to update the waveform of another wave (to be played on a different channel) it starts producing distorted signals on all channels.

Here is a test protocol for this issue:

%% Create an instance of the wavePlayer module
W = BpodWavePlayer(WavePlayerUSB);

SF=50000;  
sig_T  = 4;            
Wave_Mask = randn(1, SF*sig_T);       
Wave_Mask = 4.9*Wave_Mask/(max(abs(Wave_Mask))); 
Level_A = -2*ones(1, 100);

Fstim = 40; 
Tstim = 1;    
timeSig = 0:1/SF:Tstim;
Wave_LaserPowerSig = 4*sin(2*pi*Fstim*timeSig); 


% Program wave server
W.LoopDuration = [300 0 0 0];   % in seconds
W.LoopMode={'On', 'Off', 'Off', 'Off'};   
W.SamplingRate = SF;
W.TriggerMode = 'Master';   % triggers can force-start a new wave during playback

W.TriggerProfileEnable = 'On';
W.OutputRange = '-5V:5V';

W.setupSDCard();

W.loadWaveform(1, Level_A);    
W.loadWaveform(2, Wave_Mask);
W.loadWaveform(3, Wave_LaserPowerSig);

W.TriggerProfiles = zeros(64,4);
W.TriggerProfiles(1,:) = [2 3 0 0];
W.TriggerProfiles(2,:) = [1 0 0 0];


%% Set Bpod serial message library with correct codes to trigger waves X on analog output channels X
analogPortIndex = find(strcmp(BpodSystem.Modules.Name, 'WavePlayer1'));
if isempty(analogPortIndex)
    error('Error: Bpod WavePlayer module not found. If you just plugged it in, please restart Bpod.')
end

ResetSerialMessages;

LoadSerialMessages('WavePlayer1', ['P' 0], 99);    
LoadSerialMessages('WavePlayer1', ['P' 1], 98); 
 

%% Main loop (runs once per trial)
for currentTrial = 1:MaxTrials
    S = BpodParameterGUI('sync', S); % Sync parameters with BpodParameterGUI plugin
    
    %--- Typically, a block of code here will compute variables for assembling this trial's state machine
    
    if currentTrial>1
        Wave_LaserPowerSig = randi(4)*sin(2*pi*Fstim*timeSig); 
        W.loadWaveform(3, Wave_LaserPowerSig);
    end
    
    %--- Assemble state machine
    sma = NewStateMachine();
    sma = AddState(sma, 'Name', 'FirstState', ... % This example state does nothing, and ends after 0 seconds
        'Timer', 1,...
        'StateChangeConditions', {'Tup', 'SecondState'},...
        'OutputActions', {'WavePlayer1' 99});
    sma = AddState(sma, 'Name', 'SecondState', ... % This example state does nothing, and ends after 0 seconds
        'Timer', 1,...
        'StateChangeConditions', {'Tup', 'LastState'},...
        'OutputActions', {'WavePlayer1' 98}); 
    sma = AddState(sma, 'Name', 'LastState', ... % This example state does nothing, and ends after 0 seconds
        'Timer', 1,...
        'StateChangeConditions', {'Tup', 'exit'},...
        'OutputActions', {}); 
    
    SendStateMatrix(sma); % Send state machine to the Bpod state machine device
    RawEvents = RunStateMatrix; % Run the trial and return events
    
    %--- Package and save the trial's data, update plots
    if ~isempty(fieldnames(RawEvents)) % If you didn't stop the session manually mid-trial
        BpodSystem.Data = AddTrialEvents(BpodSystem.Data,RawEvents); % Adds raw events to a human-readable data struct
        BpodSystem.Data.TrialSettings(currentTrial) = S; % Adds the settings used for the current trial to the Data struct (to be saved after the trial ends)
        SaveBpodSessionData; % Saves the field BpodSystem.Data to the current data file
        
        %--- Typically a block of code here will update online plots using the newly updated BpodSystem.Data
        
    end
    
    %--- This final block of code is necessary for the Bpod console's pause and stop buttons to work
    HandlePauseCondition; % Checks to see if the protocol is paused. If so, waits until user resumes.
    if BpodSystem.Status.BeingUsed == 0
        W.stop();
        return
    end
end

The Level_A wave is playing in loop mode on channel 1 at the start of each trial. At that time we need to update the waveform Wave_LaserPowerSig.
If the protocol runs like this for a few trials, the played output signals eventually become distorted. Often the BpodWavePlayer needs to be powered off/on to recover the integrity of the signals.

This however does not occur if we set Loop Mode to Off and use very long signals instead.

Is there a solution for this?