diff --git a/README b/README
new file mode 100644
index 0000000..8232086
--- /dev/null
+++ b/README
@@ -0,0 +1,15 @@
+Ben Blinkenlights
+=================
+
+This project is a proof of concept implementation of Rikard Lindstrom's
+idea of using the Ben's uSD slot as a general extension interface also
+for devices that don't speak MMC or SD/SDIO. The application is a simple
+LED circuit, as suggested by David Samblas.
+
+The uSD slot gives access to six GPIOs, a 3.3 V supply that can be
+switched on and off by software, and ground. We use a simple form of
+multiplexing to drive ten LEDs with this interface.
+
+Note that one should only light one LED at a time. If multiple LEDs are
+lit, they will share the current though the common resistor, and will
+thus be less bright than a single LED.
diff --git a/bbl/bbl.c b/bbl/bbl.c
index f081655..36bbaad 100644
--- a/bbl/bbl.c
+++ b/bbl/bbl.c
@@ -1,5 +1,5 @@
 /*
- * bbl.c - Read or write any CPU register
+ * bbl.c - Produce a "Knight Rider" effect on the LED board
  *
  * Written 2010 by Werner Almesberger <werner@openmoko.org>
  *