diff --git a/README.md b/README.md
index 2a1356b..da669b1 100644
--- a/README.md
+++ b/README.md
@@ -4,8 +4,10 @@ tileLED
 A very minimalistic driver for 8x8 LED dot matrix displays.
 
 
-Based on an ATmega8 this board can drive a simple LED matrix display.
+Based on an ATmega8 this board can drive a simple LED matrix displays. There is no real "driver" circuit on the board. We just use the GPIOs of the AVR mcu to sink/source the LED current.
 
-The source code includes a simple demonstration. Paired with a DS1820 digital temperature sensor, the display shows the current temperature.
+According to the ATmega8 datasheet this usage is a bit out of spec, but tests with 3 Volt button cells were successful. Also 5 Volt supplies are okay.
+
+The source code includes a simple demonstration application. Paired with a DS1820 digital temperature sensor, the display shows the current temperature and records the minimal and maximal temperature ever measured.
 
 A Blog post on http://www.steffenvogel.de will follow.