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--- kpnl:biopac:dio [2015/02/15 13:38] – admin
+++ kpnl:biopac:dio [2015/05/16 10:20] (current) – [Acquiring Digital Codes] admin
@@ Line 1: / Line 1: @@
 ====== Acquiring Digital Codes ======
-It is critical that we acquiring 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 the 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 using the Biopac MP150.
+It is critical that we acquire time-locked digital codes upon presentation of each stimulus. These codes are used to bin the data according to stimulus type during analysis. This is also essential for creating event-related averages of the 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 using the Biopac MP150.
 ===== Hardware =====
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   * [[http://www.winfordeng.com/products/brk25mf.php|Winford DB25 Dual Connector Breakout Board]]
     * 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.
+  * [[http://www.biopac.com/isolated-digital-interface-printer-port|Biopac I/O]]
 <WRAP center round box 80%>
@@ Line 19: / Line 20: @@
   - A 25-pin ribbon cable connects the breakout board to the MP150
 </WRAP>
 ===== Software =====
@@ Line 25: / Line 25: @@
 The LabJack U3 can be controlled via several different programs and languages. We use the [[http://labjack.com/support/labjackpython|LabJack Python module]] to send codes via [[http://www.psychopy.org/|PsychoPy]].
-To date, I have only had success controlling the LabJack from a computer running the Mavericks OS (not Yosemite). The computer should have [[https://developer.apple.com/xcode/|Xcode]] (including the **Command Line Tools**) installed. The libusb package should also be installed (see [[http://labjack.com/support/linux-and-mac-os-x-drivers|here]] for details). Finally, the [[http://labjack.com/support/linux-and-mac-os-x-drivers|LabJack exodriver]] and [[http://labjack.com/support/labjackpython|LabJack Python module]] should be installed.
+The computer (Mac) should have [[https://developer.apple.com/xcode/|Xcode]] (including the **Command Line Tools**) installed. The libusb package should also be installed (see [[http://labjack.com/support/linux-and-mac-os-x-drivers|here]] for details). Finally, the [[http://labjack.com/support/linux-and-mac-os-x-drivers|LabJack exodriver]] and [[http://labjack.com/support/labjackpython|LabJack Python module]] should be installed.
 Below is sample code for sending digital codes.  Additional details can be found [[http://labjack.com/support/labjackpython/low-level|here]] and [[http://labjack.com/support/u3/users-guide/5.2.5.10|here]].
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 **3.** Check the **Acquire** box next to channels 8-15. The **Plot** and **Value** boxes can remain unchecked.
-The MP150 does not read the 8-bit code. Rather, it is simply acquiring 8 separate channels of digital input. To covert these to decimal stimulus codes we must perform the following steps.
+<WRAP center round info 60%>
+  * Pins 2-9 on the DB25 map to digital inputs 8-15 on the MP150
+</WRAP>
+The MP150 does not read the 8-bit code. Rather, it is simply acquiring 8 separate channels of digital input. We need to create an additional channel that will take the result of an expression (that we define) as input. The expression will convert the 8 binary channels to a single decimal stimulus code.
+**4.** Select **Calculation**.
+**5.** Check the boxes for **Acquire**, **Plot**, and **Value**.
+**6.** From the “preset” dropdown menu select **''Expression''**.
+**7.** Select **Setup**
-Select “Calculation"
+**8.** Enter the following formula: ''(D8*1 + D9*2 + D10*4 +D11*8 + D12*16 + D13*32 + D14*64 + D15*128) / 5''
-Check the boxes for; Acquire, Plot, Value
+\\
-From the “preset” dropdown menu select “Expression"
+(note: we divide by 5 because the input is read as 5 volts. So a digital code of ''255'' would be summed to 1275.)
-Select ‘Setup"
-Enter the following formula:
-(note: the divide by 5 at the end is because the ‘high’ position is 5 volts. so a code of 255 would be summed to 1275)
-(D8*1 + D9*2 + D10*4 +D11*8 + D12*16 + D1x3*32 + D14*64 + D15*128) / 5