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-rw-r--r--Documentation/input/rotary-encoder.txt8
1 files changed, 6 insertions, 2 deletions
diff --git a/Documentation/input/rotary-encoder.txt b/Documentation/input/rotary-encoder.txt
index bddbee188624..46a74f0c551a 100644
--- a/Documentation/input/rotary-encoder.txt
+++ b/Documentation/input/rotary-encoder.txt
@@ -9,8 +9,9 @@ peripherals with two wires. The outputs are phase-shifted by 90 degrees
and by triggering on falling and rising edges, the turn direction can
be determined.
-Some encoders have both outputs low in stable states, whereas others also have
-a stable state with both outputs high (half-period mode).
+Some encoders have both outputs low in stable states, others also have
+a stable state with both outputs high (half-period mode) and some have
+a stable state in all steps (quarter-period mode).
The phase diagram of these two outputs look like this:
@@ -32,6 +33,9 @@ The phase diagram of these two outputs look like this:
|<-->|
one step (half-period mode)
+ |<>|
+ one step (quarter-period mode)
+
For more information, please see
https://en.wikipedia.org/wiki/Rotary_encoder