add note on JTAG disable fuse

README.md

@@ -98,6 +98,10 @@
 	<li><a href='i2c/loadcell-reading-v-force.png'>Results</a></li>
 </ul>
 
+## Pro Tips Etc
+
+ - Some XMEGAs have a JTAG peripheral (to program w/o PDI, and for debugging). There is a JTAG fuse which is set 'on' to default: this will prevent you from using the pins that JTAG uses. On the XMEGA A3U series, this is in PortB. 
+
 ## Atmel Studio Toolchain
 
 ``` !warn! windows only, sorry ```

circuit/bbxmega/eagle.epf

 [Eagle]
-Version="08 03 02"
+Version="09 01 01"
 Platform="Windows"
 Globals="Globals"
 Desktop="Desktop"
@@ -10,39 +10,20 @@ UsedLibraryUrn="urn:adsk.eagle:library:217"
 UsedLibraryUrn="urn:adsk.eagle:library:325"
 UsedLibraryUrn="urn:adsk.eagle:library:371"
 UsedLibrary="D:/Dropbox (Personal)/CBA/doc/libraries/eagle/fab.lbr"
-UsedLibrary="D:/Dropbox (Personal)/CBA/doc/libraries_jake/eagle/jake/tag-connect-2030.lbr"
 UsedLibrary="D:/Dropbox (Personal)/CBA/doc/libraries_jake/eagle/jake/tag-connect-2050.lbr"
 UsedLibrary="D:/Dropbox (Personal)/CBA/doc/libraries_jake/eagle/sparkfun/SparkFun-Connectors.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/Comparators.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/Digital.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/FilterProducts.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/Misc.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/Opamps.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/Optos.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/PAsystem.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/PowerProducts.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/References.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/SpecialFunctions.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/capmeter.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/diode.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/lt-spice-simulation.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/lt-supply.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/rload.lbr"
-UsedLibrary="C:/EAGLE 8.3.2/lbr/ltspice/sym.lbr"
 UsedLibrary="D:/Dropbox (Personal)/CBA/doc/libraries_jake/eagle/marekr/borkedlabs-passives.lbr"
 
 [Win_1]
-Type="Schematic Editor"
-Loc="0 0 1919 1016"
-State=1
-Number=2
-File="bbxmega.sch"
-View="-13.5313 5.97904 167.1 132.776"
-WireWidths=" 0.0762 0.1016 0.127 0.15 0.2 0.2032 0.254 0.3048 0.4064 0.508 0.6096 0.8128 1.016 1.27 2.54 0.1524"
+Type="Board Editor"
+Number=1
+File="bbxmega.brd"
+View="-0.0538375 -4.25636 63.4947 47.255"
+WireWidths=" 0.0762 0.1016 0.127 0.15 0.2 0.2032 0.3048 0.4064 0.508 0.6096 0.8128 1.016 1.27 2.54 0.1524 0.254"
 PadDiameters=" 0.254 0.3048 0.4064 0.6096 0.8128 1.016 1.27 1.4224 1.6764 1.778 1.9304 2.1844 2.54 3.81 6.4516 0"
 PadDrills=" 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.65 0.7 0.75 0.8 0.85 0.9 1 0.6"
 ViaDiameters=" 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.3 0"
-ViaDrills=" 0.2 0.25 0.3 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 1 0.35"
+ViaDrills=" 0.25 0.3 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 1 0.35 0.8636"
 HoleDrills=" 0.2 0.25 0.3 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 1 0.35"
 TextSizes=" 0.254 0.3048 0.4064 0.6096 0.8128 1.016 1.27 1.4224 1.6764 1.9304 2.1844 2.54 3.81 5.08 6.4516 1.778"
 PolygonSpacings=" 0.254 0.3048 0.4064 0.6096 0.8128 1.016 1.4224 1.6764 1.778 1.9304 2.1844 2.54 3.81 5.08 6.4516 1.27"
@@ -53,14 +34,14 @@ DimensionExtWidths=" 0.127 0.254 0.1 0.13 0.26 0"
 DimensionExtLengths=" 1.27 2.54 1 2 3 0"
 DimensionExtOffsets=" 1.27 2.54 1 2 3 0"
 SmdSizes=" 0.3048 0.1524 0.4064 0.2032 0.6096 0.3048 0.8128 0.4064 1.016 0.508 1.27 0.6604 1.4224 0.7112 1.6764 0.8128 1.778 0.9144 1.9304 0.9652 2.1844 1.0668 2.54 1.27 3.81 1.9304 5.08 2.54 6.4516 3.2512 1.27 0.635"
-WireBend=0
-WireBendSet=31
+WireBend=3
+WireBendSet=0
 WireCap=1
 MiterStyle=0
 PadShape=0
 ViaShape=1
 PolygonPour=0
-PolygonRank=0
+PolygonRank=1
 PolygonThermals=1
 PolygonOrphans=0
 TextRatio=8
@@ -75,17 +56,13 @@ SwapLevel=0
 ArcDirection=0
 AddLevel=2
 PadsSameType=0
-Layer=91
-Views=" 1: -13.5313 5.97904 167.1 132.776"
-Sheet="1"
+Layer=1
 
 [Win_2]
-Type="Board Editor"
-Loc="0 0 1919 1016"
-State=1
-Number=1
-File="bbxmega.brd"
-View="-1.29872 8.23325 42.8321 44.005"
+Type="Schematic Editor"
+Number=2
+File="bbxmega.sch"
+View="35.5536 22.2327 122.664 83.3809"
 WireWidths=" 0.0762 0.1016 0.127 0.15 0.2 0.2032 0.254 0.3048 0.4064 0.508 0.6096 0.8128 1.016 1.27 2.54 0.1524"
 PadDiameters=" 0.254 0.3048 0.4064 0.6096 0.8128 1.016 1.27 1.4224 1.6764 1.778 1.9304 2.1844 2.54 3.81 6.4516 0"
 PadDrills=" 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.65 0.7 0.75 0.8 0.85 0.9 1 0.6"
@@ -101,14 +78,14 @@ DimensionExtWidths=" 0.127 0.254 0.1 0.13 0.26 0"
 DimensionExtLengths=" 1.27 2.54 1 2 3 0"
 DimensionExtOffsets=" 1.27 2.54 1 2 3 0"
 SmdSizes=" 0.3048 0.1524 0.4064 0.2032 0.6096 0.3048 0.8128 0.4064 1.016 0.508 1.27 0.6604 1.4224 0.7112 1.6764 0.8128 1.778 0.9144 1.9304 0.9652 2.1844 1.0668 2.54 1.27 3.81 1.9304 5.08 2.54 6.4516 3.2512 1.27 0.635"
-WireBend=1
-WireBendSet=0
+WireBend=0
+WireBendSet=31
 WireCap=1
 MiterStyle=0
 PadShape=0
 ViaShape=1
 PolygonPour=0
-PolygonRank=1
+PolygonRank=0
 PolygonThermals=1
 PolygonOrphans=0
 TextRatio=8
@@ -123,12 +100,12 @@ SwapLevel=0
 ArcDirection=0
 AddLevel=2
 PadsSameType=0
-Layer=1
+Layer=91
+Views=" 1: 35.5536 22.2327 122.664 83.3809"
+Sheet="1"
 
 [Win_3]
 Type="Control Panel"
-Loc="0 0 1919 1039"
-State=1
 Number=0
 
 [Desktop]