see: http://mbed.org/users/okini3939/notebook/low-power-lpc81x/

Revision:
1:f336c9774f7a
Parent:
0:349dc3aae37a
--- a/swm.c	Thu Jun 06 09:52:40 2013 +0000
+++ b/swm.c	Fri Jun 07 22:47:35 2013 +0000
@@ -45,8 +45,7 @@
     /* SWCLK */
     /* SWDIO */
     /* RESET */
-    /* CLKIN */
-    LPC_SWM->PINENABLE0 = 0xffffff33UL; 
+    LPC_SWM->PINENABLE0 = 0xffffffb3UL; 
 }
 
  /**********************************************************************