clarify which sonar sensor the holder is for

diff --git a/3d-printables/sonar-table-top-holder.scad b/3d-printables/sonar-table-top-holder.scad
index 42578116602547606d7927d23504471146d9f736..56d58f9c7af31d61ccc14866d0caf3540dd106ab 100644 (file)
--- a/3d-printables/sonar-table-top-holder.scad
+++ b/3d-printables/sonar-table-top-holder.scad
@@ -4,6 +4,14 @@
 // https://gitorious.org/ozzloy/challenge-bot
 // https://github.com/waynegramlich/challenge-bot
 
+/*
+  this holds an hc-sr04 sonar sensor to a 3/16 inch deck.
+  http://fritzing.org/projects/hc-sr04-project
+  it can hold the sonar sensor either facing down, or forwards.
+  when facing down, it can detect if it passes over the edge of a table.
+  when facing forwards, it can detect and follow something in front of it.
+ */
+
 $fn = 60;
 
 // 3/16 inch in mm deck_depth = 4.7625;