1 files changed, 7 insertions, 0 deletions
diff --git a/bin/flash.sh b/bin/flash.sh
index 019631a..0423c90 100755
--- a/bin/flash.sh
+++ b/bin/flash.sh
@@ -2,6 +2,13 @@
 
 # Flashes both fuses and firmware.
 
+if [ -z "$1" ]; then
+  echo "Usage: flash.sh MCU myprogram[.hex]"
+  echo "MCU is a number, like '13' for attiny13 or '841' for attiny841"
+  echo "The .hex suffix is optional."
+  exit
+fi
+
 set -e
 
 BASEDIR=$(dirname "$0")