diff --git a/README.md b/README.md
index 5c5e7b2..bce71c3 100644
--- a/README.md
+++ b/README.md
@@ -36,9 +36,11 @@ LEDs: 8 blinkleds, 1 usb led
 
 RTC clock, quartz and battery
 
-GPDI 3.3V-5V bidirectional level shifter
-General Purpose Differential Interface,
-female socket more-or-less compatible
+3.3V-5V I2C bidirectional level shifter for GPDI
+
+GPDI is General Purpose Differential Interface,
+Electrically LVDS, mostly TMDS tolerant
+female receptacle more-or-less compatible
 with digital monitors/TVs
 
 # Todo