[Lancelot] Something to watch out for...

H. Peter Anvin hpa at zytor.com
Tue Sep 21 12:47:12 PDT 2004

I just managed to get bitten by this -- perhaps I'm the only one -- so 
here is a warning:

At least on the Cyclone edition board, the power to the CompactFlash 
slot is gated!

I hadn't put cf_power in the pinlist I published ages ago, and as a 
result it was left floating.  The bizarre result was that the CF card 
worked for reading, but not for writing!  I guess there was just enough 
power let through that the capacitors held Vcc high enough to work 
(presumably above 3.2 V or so) except when it was writing.

It was a real puzzler to figure out.

Instantiating cf_power (pin M13) and driving it to VCC (1) solved the 

I have uploaded an updated pin list to:



More information about the Lancelot mailing list