Differences

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--- roborio_digital_io [2018/01/28 15:01] – [Selecting from among more than two alternatives] tell
+++ roborio_digital_io [2018/12/11 22:31] (current) – [Selecting from among more than two alternatives] tell
@@ Line 98: / Line 98: @@
-====== Selecting from among more than two alternatives ======
-One DIO input can tell the software to do one out of two possible alternatives.  What if we want to select from between more than two?  Use more DIO inputs!
-We could use two DIOs for two different limit switches: one for UP, one for DOWN, and if neither switch is closed, we interpret that to mean the mechanism is somewhere in between.
-Suppose we want to select from four different autonomous routines.  we could use two switches, and tell the drive team to set them according to a table like this:
-  * 0: Closed, Closed - do nothing
-  * 1: Closed, Open   - drive forward
-  * 2: Open, Closed   - drive forward and place power cube
-  * 3: Closed, Closed - drive forward, turn left, drive, turn right, drive, and then place cube
-[picture]?
-But requiring the drivers to read the chart, even if it is written on the robot, is error prone.
-A better **user interface** would be a rotary switch.
-[picture]
-A typical rotary switch contains one or more "levels" each with a moving contact that can connect to one fixed contact at a time.  We typically draw the schematic for such a switch like this:
-{{ :rotary-switch.png?nolink |}}
-We can connect a two-level rotary switch like this to encode those four positions into the four possible values for two DIO inputs:
-{{ :rotary-binary2.png?nolink |}}
+What if we want to select between more than two choices?   See "fun with switches" on the page [[Switches as Digital IO]]
 ====== Conclusion ======