document power supply requirements for v0.2

diff --git a/TeleMetrum/index.mdwn b/TeleMetrum/index.mdwn
index 46f16f7e5f0ee9dd8b6259e5563ca9382e9a9ff3..02fd7f430c510d6314bc95570eb9349b30ead711 100644 (file)
--- a/TeleMetrum/index.mdwn
+++ b/TeleMetrum/index.mdwn
@@ -118,6 +118,12 @@ necessary to support the companion board interface added in v0.2.
   place parts!  Without an inspection microscope, loading and testing these
   boards might be impossible.
 
   place parts!  Without an inspection microscope, loading and testing these
   boards might be impossible.
 

+* The addition of on-board GPS in v0.2 means that the total power consumption
+  can exceed the rate at which we draw power from the USB interface, 
+  particularly when the GPS is in cold start mode.  This means a battery must 
+  be attached during operation, and also that the battery will only charge 
+  effectively from USB when the board is turned off.
+

 * The v0.1 artwork had three issues, two of which required physical rework
   on each board.  All of these issues were fixed in v0.2.
 
 * The v0.1 artwork had three issues, two of which required physical rework
   on each board.  All of these issues were fixed in v0.2.