Differences

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--- dio_tester_and_breakout [2018/12/28 15:10] – [Building the Board] tell
+++ dio_tester_and_breakout [2019/10/07 23:16] (current) – [Revision 2: Jan 2019] tell
@@ Line 53: / Line 53: @@
 ======Building the Board======
-Here's our first assembled board, connected to a power source for testing.   We used our [[fakerio digital input tester]], but your could use a RoboRIO or any source of +5v power.
+Here's our first assembled board, connected to a power source for testing.   We used our [[fakerio digital input tester]], but you could use a RoboRIO or any source of +5v power.
 {{ :img_20181214_175255951_1small.jpg?400 |}}
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 TODO: picture of this assembly.
+====== Revision 2: Jan 2019 ======
+We made three minor changes to this board design for the 2019 competition season.\\
+{{ :diotester-2019s.jpg?300|}}
+  * add the text "2019 season" to the back of the board, to help identify which are legal for this season, and which were the 2018 prototypes.  This will be handy next year too: boards built in previous years are fair game for off-robot testing and practice robots, but not legal for competition.
+  * add two tiny mounting holes.  To avoid enlarging the board, these holes only accept #2 bolts.  nylon hardware is recommended, as they're quite close to components
+  * add silkscreen labeling the three signals on the connectors "ground", "signal", and "+" power.
+This version of the board design is https://oshpark.com/projects/SlhiHbwO
+====== Proposed Revision 3: Feb 2019 ======
+A requirement that came up for the [[2019 cargo sensor]] is to gate together the outputs of several infrared sensors.  One way to do this is to invert each one, and then OR them together.  A proposed scheme was to add the inversion to the DIO board used at each sensor, and then wire those inverted output together in a wire-OR configuration.
+The proposed schematic is:
+{{ :img_20190224_115824025.jpg |}}
+The 4-pin jumper assembly allows the 2n7000 mosfet to be omitted entirely (making a board compatible with the earlier versions. Alternately, it can be used to invert either an input or output signal.  In boards where the mosfet is used, the pins for the sensor connections are seperated from the roborio connection and a copy that can be chained through to additional boards.
+We might build this one, or might build a separate logic gate board.  or both.
+One limitation of the schematic above is that while the inverted outputs can be wire-ORed and not affect the on-board status LED, wire-ORing the inputs would cause all of the LEDs to light if any input was low.  A more elaborate, buffered design would allow either true or inverted output to be wire-ORed, while still giving a useful status of the input.