Issues communicating with Analog Input module

og100

Hi,

I'm a relative newcomer to Bpod, and am having trouble communicating with the Analog Input module...

I am using Matlab and PsychToolBox in Ubuntu, and can successfully connect and run some of the example Bpod protocols that make use of other modules e.g. HiFiSound2AFC works fine with the HiFi module, suggesting the general Bpod installation is okay. The AI module is detected in the Bpod console tab, and I have paired it with a USB port.

However, I cannot connect to the module from the Matlab cmd line:

A = BpodAnalogIn(BpodSystem.ModuleUSB.AnalogIn1);
Error: unable to connect to Bpod Analog Input module.

If I remove the config string in line 121 ArCOMObject_Ain.m

from this:
obj.Port = IOPort('OpenSerialPort', portString, 'BaudRate=256000, OutputBufferSize=100000, InputBufferSize=100000, DTR=1');

to this:
obj.Port = IOPort('OpenSerialPort', portString);

I can at least find and connect the module:

A = BpodAnalogIn(BpodSystem.ModuleUSB.AnalogIn1);
Analog Input Module found.

and I can open the oscilloscope GUI by executing A.Scope

But when I click 'Run' in the scope GUI I get the following warnings:

"Error while evaluating TimerFcn for timer 'timer-2'
Index exceeds the number of array elements. Index must not exceed 64."

And when I click 'Stop' I get the following error messages:

"Index exceeds the number of array elements. Index must not exceed 64.

Error in ArCOMObject_Ain/read (line 303)
varargout{i} = uint8(ByteString(Pos😛os+nValues(i)-1)); Pos = Pos + nValues(i);

Error in BpodAnalogIn/scope_StartStop (line 657)
obj.Port.read(obj.Port.bytesAvailable, 'uint8');

Error in BpodAnalogIn>@(h,e)obj.scope_StartStop() (line 541)
'Callback',@(h,e)obj.scope_StartStop(), 'BackgroundColor', [0.7 0.7 0.7], 'FontSize', TitleFontSize,...

Error while evaluating UIControl Callback."

I can trace i issue to ArCOMObject_Ain.m here

switch obj.Interface
case 0
ByteString = fread(obj.Port, nTotalBytes, 'uint8')';
case 1

ByteString = IOPort('Read', obj.Port, 1, nTotalBytes);
case 2
ByteString = srl_read(obj.Port, nTotalBytes);
end

Where IOPort Read returns a 64 length vector in ByteString that does not match nTotalBytes.

I'm guessing there is something going wrong with the serial port communication somewhere but any tips would be much appreciated thanks!

Oli

Josh

Hello Oli,

Try:

obj.Port = IOPort('OpenSerialPort', portString, ['ReceiveTimeout=0.05, BaudRate=192000, 
OutputBufferSize=1000000, InputBufferSize=1000000, 
DTR=1, PollLatency=0.0001, StartBackgroundRead=1']);

This will start a background process to collect the data from the OS buffer, which gets read out at your next call to IOPort('Read')

If this works we'll push it out in the next update. Really we should get rid of the special ArCOM class for BpodAnalogIn, and add its functionality to the main one.

-Josh

og100

Hi Josh,

Thanks for getting back to me, unfortunately this has not solved the issue an I still cannot connect to the AI module

A = BpodAnalogIn(BpodSystem.ModuleUSB.AnalogIn1);
Error in function Close: Usage error
Invalid port handle -1 provided. No such port open. Maybe you closed it beforehand?
Error in function Close: Usage error
Invalid port handle -1 provided. No such port open. Maybe you closed it beforehand?
Warning: The following error was caught while executing 'ArCOMObject_Ain' class destructor:
Error using IOPort
Usage:

IOPort('Close', handle);

Error in ArCOMObject_Ain/delete (line 338)
IOPort('Close', obj.Port);

Error in ArCOMObject_Ain (line 62)
obj.Port = [];

Error in BpodAnalogIn (line 77)
obj.Port = ArCOMObject_Ain(portString, 115200);

In ArCOMObject_Ain (line 62)
In BpodAnalogIn (line 77)
Error using BpodAnalogIn (line 79)
Error: unable to connect to Bpod Analog Input module.

Thanks again,
Oli

Josh

Hello Oli,

What version of Ubuntu and MATLAB are you running?
Please also run PsychToolboxVersion and share the result.

One thing to try: In BpodAnalogIn.m, change line 77 from

obj.Port = ArCOMObject_Ain(portString, 115200);

obj.Port = ArCOMObject_Ain(portString, 115200, 'Java');

This will force communication between the module and PC to use MATLAB's higher latency Java serial interface instead of PsychToolbox.
Depending on your setup, you may need to play with Linux permissions to connect to the port this way (add your account to the dialout group, etc)

-Josh

og100

Hi Josh,

That seems to have done the trick thanks a lot!

Oli