Jon Hart

BDM ignored when /XCLKS tied to GND (Pierce config)

Discussion created by Jon Hart on May 26, 2006
Latest reply on Jun 6, 2006 by Jon Hart
We are using MC9S12DP512 with Pierce oscillator.  Debugging with Cosmic ZAP and P&E USB Multilink.
The Freescale docs say that /XCLKS must be grounded on reset to get the Pierce oscillator to work.  This is true.  We are finding, however, that this prevents the Multilink from working.  In fact, with the BDM cable connected, the processor resets and runs (which it shouldn't do) if /XCLKS is tied to GND.
We are coming to the conclusion that there is a bug somewhere, since the P&E dev board has a Pierce Crystal config but THEY dont tie /XLCKS to GND ( how come? )
If we dont GND /XCLKS we never acheive a PLL lock and stay in "limp home" mode.
Any help much appreciated!