README: warn about channel output during testing.

diff --git a/README b/README
index 74fda4421a4235165a5a998af19446209295a06f..15d5c6dbc36a07694a4967082921c7b0b1144759 100644 (file)
--- a/README
+++ b/README
@@ -70,10 +70,19 @@ See the examples in the `doc` directory.
 Testing
 =======
 
-Integration tests with::
+Run integration tests with::
 
     $ nosetests --with-doctest --doctest-extension=txt doc
 
+The analog integration tests read from analog input channels 0 through
+3, and write to analog output channels 0 and 1, so you'll need a board
+with that many channels.  You should also make sure that the analog
+output channels aren't plugged into anything sensetive, since the
+tests sweep their output around over a reasonable chunk of the channel
+range.  Some of the internal unit tests also write, so it's safest to
+just disconnect all digital lines and analog outputs before running
+the tests.
+
 Run both integration tests and internal unit tests with::
 
     $ ./test.sh