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--- dio_tester_and_breakout [2018/11/30 16:53] – ilena
+++ dio_tester_and_breakout [2019/10/07 23:16] (current) – [Revision 2: Jan 2019] tell
@@ Line 1: / Line 1: @@
 During the 2018 season, we hand-wired a little board to break out and debug
-the Digital I/O wiring to the break-beam sensor.  This project is about a PC Board to replace that,
+the Digital I/O wiring to the break-beam sensor on our [[2018 intake|intake]]  This project is about a PC Board to replace that,
 and for other DIO testing and wiring.
@@ Line 29: / Line 29: @@
 The schematic and board files for our design is in our [[https://github.com/Team-4795/pcboards-2018/tree/master/dioboard2 | github ]]
-We used this DIO tester design to start learning about how to do schematics and board designs; our [[printed circuit boards]] pages use this design as an illustration.
+We used this DIO tester design to start learning about how to do schematics and board designs; our [[printed circuit boards]] tutorial pages use this design as an illustration.
-Here's a screen shot of the complete schematic:
+Here's a screenshot of the complete schematic:
-(TODO picture)
+{{ :dio_board_schematic.png?400 |}}
 On the schematic are:
-  * a basic LED circuit that lights up yellow if the +5v power is present and connected.
+  * a [[basic LED circuit]] that lights up yellow if the +5v power is present and connected.
   * a slightly modified LED circuit that lights a red LED if the signal wire is LOW (connected to ground)
   * Four connectors: one socket for connecting to the RoboRio, and three headers for sensors.
@@ Line 49: / Line 49: @@
  https://oshpark.com/shared_projects/UVZvYEPw
-We're expecting them back in early December 2018.
+Those first boards arrived early December 2018.
+{{ :img_20181206_215829056_1small.jpg?400 |}}
 ======Building the Board======
+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 |}}
+Another copy of the board was assembled differently, with the Break-beam sensor wires soldered directly to the board.
+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.