diff --git a/firmware/config/boards/hellen/hellen128/connectors/main.yaml b/firmware/config/boards/hellen/hellen128/connectors/main.yaml
index 976ea9e91b..6d3a409630 100644
--- a/firmware/config/boards/hellen/hellen128/connectors/main.yaml
+++ b/firmware/config/boards/hellen/hellen128/connectors/main.yaml
@@ -1,3 +1,5 @@
+# https://docs.google.com/spreadsheets/d/1x9pB8oRpY1ISkrGYIsa5j2MrnQVA644REb9Ebl41tcw
+
 pins:
   - pin: A1
     function: NC