Differences

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--- kpnl:psychopy [2015/03/28 12:32] – [Hardware] admin
+++ kpnl:psychopy [2018/01/21 16:45] (current) – admin
@@ Line 19: / Line 19: @@
 </WRAP>
+====== Tutorials ======
-====== Notes on sending digital event codes ======
+[[https://www.youtube.com/watch?v=9BqRyut2UZk|PsychoPy Tutorials]]
+====== Miscellaneous Tips ======
+  * Do not use "filename" as a variable (i.e., column header in Excel). This conflicts with a variable in PsychPy and will result in some strange names for your output files.
+    * There are likely other variable names to avoid, but this is the first I've come across
+====== Sending digital event codes ======
 It is critical that we acquire stimulus-locked digital codes so that we can bin the data according to stimulus type during analysis. This is also essential for creating event-related averages of psychophysiological data (e.g. creating ERPs from EEG data) as it gives us the precise onset time of each stimulus. Below is a description of the hardware, software, and steps necessary for sending and acquiring such codes with PsychoPy and the BioSemi ActiveTwo system.
-===== Hardware =====
-  * [[http://labjack.com/u3|LabJack U3 DAQ device]]
+===== Sending an entire byte at once =====
-    * The stimulus presentation computer interfaces with this device via USB. The device then outputs the 8-bit digital signal which is relayed to the MP150 via a 37-pin ribbon cable which connects to a parallel port on the ActiveTwo USB receiver.
-  * [[http://www.winfordeng.com/products/brksd37.php|Winford DB37 'Slim' Female Connector Breakout Board]]
+//The following describes an issue and fix that is relevant for PsychoPy 1.83 and older. This fix will be included in version 1.84 and beyond. For a more detailed description of the issue and resolution see this PsychoPy [[https://groups.google.com/forum/#!searchin/psychopy-users/bit$20latency/psychopy-users/gN9ZSMgvTsE/uq5xePwSEwAJ
-    * This breakout board (aka terminal board or terminal block) gives us an easy way of wiring the output from the LabJack U3 to the ribbon cable.
+|forum thread]]//
-  * [[http://www.biosemi.com/receiver.htm|ActiveTwo USB receiver I/O]]
+The code used in PsychoPy to send digital codes via the LabJack device sets each bit sequentially, rather than setting the entire byte in parallel. This introduces a ~400 microsecond latency between each bit. This latency has two important consequences for use in EEG. 1) Sending a code of "255" (11111111) will have a latency relative to the stimulus onset that is ~3 milliseconds longer than sending a code of "1" (00000001). Of course, this introduces a confound when contrasting the latency of two conditions that use those codes.
+To fix the problem, one needs to modify a little bit of code included in the OS X PsychoPy standalone package.
+  - Right click on the PsychoPy application and select ''Show Package Contents''
+  - Navigate to /Applications/PsychoPy2/Contents/Resources/lib/python2.7/psychopy/hardware
+  - Open the ''labjacks.py'' file for editing (you might want create a copy of the file before making changes)
+  - Replace the class U3 definition
+Replace this code:
+<code python>
+class U3(u3.U3):
+    def setData(self, byte, endian='big', address=6008):
+        """Write 1 byte of data to the U3 port
+        parameters:
+            - byte: the value to write (must be an integer 0:255)
+            - endian: ['big' or 'small'] determines whether the first pin is the least significant bit or most significant bit
+            - address: the memory address to send the byte to
+                - 6008 = EIO (the DB15 connector)
+        """
+        if endian=='big':
+            byteStr = '{0:08b}'.format(byte)[-1::-1]
+        else:
+            byteStr = '{0:08b}'.format(byte)
+        [self.writeRegister(address+pin, int(entry)) for (pin, entry) in enumerate(byteStr)]
+</code>
+with this code:
+<code python>
+class U3(u3.U3):
+    def setData(self, byte, endian='big', address=6701):
+        """Write 1 byte of data to the U3 port
+        parameters:
+            - byte: the value to write (must be an integer 0:255)
+            - endian: ['big' or 'small'] (ignoring) determines whether the first pin is the least significant bit or most significant bit
+            - address: the memory address to send the byte to
+                - 6700 = FIO
+                - 6701 (default) = EIO (the DB15 connector)
+                - 6702 = CIO
+        """
+        #Upper byte is the writemask, and lower byte is the 8 lines/bits to set. Bit 0 = line 0, bit 1 = line 1, bit 2 = line 2, etc.
+        self.writeRegister(address, 0xFF00 + (byte&0xFF))
+</code>
+==== LabJack Port Addresses ====
+https://labjack.com/support/datasheets/u3/hardware-description/db15
-<WRAP center round box 80%>
-{{ :kpnl:biopac:labjack.png?350 |}}
-  - USB from stimulus presentation computer
-  - 8-bit digital output from I/O lines FIO0-FIO7.
-    - A separate wire connects each line to the breakout board.
-  - Wires are connected to screw terminals on the breakout board. Each terminal is connected to a single pin of the male/female DB-25 connectors.
-    - FIO0-FIO7 should be wired to terminals 2-9 of the breakout board.
-    - The ground should be wired to terminal 18 of the breakout board.
-  - A 25-pin ribbon cable connects the breakout board to the MP150
-</WRAP>
 ===== Setting the default LabJack address =====
-  * PsychoPy has a built-in python library to drive the LabJack DAQ device. By default, PsychoPy uses the address for the "EI0" DB15 pins (address = 6008). We use the "FIO" terminal blocks so we need to specify the correct address (''6000''). In order to use the "FIO" terminal we need to add the following custom code component to the beginning our Builder experiment. PsychoPy users [[https://groups.google.com/forum/#!topic/psychopy-users/Fvz3lSnkAWI|thread]].
+<note important>
+**The information contained in this box is moot if you use the method above to change the port address**
+PsychoPy has a built-in python library to drive the LabJack DAQ device. By default, PsychoPy uses the address for the "EI0" DB15 pins (address = 6008). We use the "FIO" terminal blocks so we need to specify the correct address (''6000''). In order to use the "FIO" terminal we need to add the following custom code component to the beginning our Builder experiment. PsychoPy users [[https://groups.google.com/forum/#!topic/psychopy-users/Fvz3lSnkAWI|thread]].
 <code python>
@@ Line 53: / Line 114: @@
         [self.writeRegister(address+pin, int(entry)) for (pin, entry) in enumerate(byteStr)]
 labjacks.U3.setData = mySetData
-</code>
+</code></note>
 ===== Initializing the LabJack =====
 ==== Status attribute ====
-  * There seems to be a bug in Builder that results in an attribute of the p_port not being initialized. Running an experiment with LabJack digital codes that was built in Builder will give the following error.
+  * There seems to be a bug in Builder that results in an attribute of the p_port not being initialized (see psychopy users [[https://groups.google.com/forum/#!searchin/psychopy-users/p_port.status/psychopy-users/7aX-5nDuqbU/uehchw6LGdcJ|thread]]). Running a  Builder-built experiment with LabJack digital codes will give the following error.
 <code python>