diff --git a/README.md b/README.md
index 74b99ad..1d889b0 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,15 @@
 # Han Mqtt Adapter
+Han port pinout:
+1. 5V
+2. Data request (connect to 5V to enable)
+3. GND
+4. NC
+5. DATA (TX 115200 inverted)
+6. GND
+
+Add voltage divider to Pico RX pin:
+- 10k between pico RX pin and GND
+- 10k between HAN pin 5 and pico RX pin
 
 ![front](20220814_231222.MEDIUM.jpeg)
 ![back](20220814_231229.MEDIUM.jpeg)