1 files changed, 6 insertions, 0 deletions
diff --git a/bin/build.sh b/bin/build.sh
index 6920a3f..ddd2a72 100755
--- a/bin/build.sh
+++ b/bin/build.sh
@@ -3,6 +3,12 @@
 # Instead of using a Makefile, since most of the firmwares here build in the
 # same exact way, here's a script to do the same thing
 
+if [ -z "$1" ]; then
+  echo "Usage: build.sh MCU myprogram"
+  echo "MCU is a number, like '13' for attiny13 or '841' for attiny841"
+  exit
+fi
+
 export ATTINY=$1 ; shift
 export PROGRAM=$1 ; shift
 export MCU=attiny$ATTINY