John Erickson

9S12DJ64 oscillator and BDM question

Discussion created by John Erickson on Jun 27, 2010
Latest reply on Jul 30, 2010 by John Erickson

Hi all,

I successfully designed and realized a project using an older HC12 processor back in 2003, so I am now trying to use the 9S12DJ64 to take its place.  I have two questions:

1)  I am using a Pierce oscillator on my 9S12DJ64 with an 8 MHz crystal (R_B=10M, with bypass caps into EXTAL and XTAL both at 22pF),  PE7 driven low, VDDPLL bypassed to GND with 100nF.  The PLL components across XFC and VDPLL (using the Motorola filter application) are 2.7kohm in series with 4.7nF and those in parallel with a 470pF.  However, my 68HC912B32 eval board will not take control of my 9S12DJ64 via BDM, so I suspect the 9S12DJ64 oscillator is not functioning.  Is there anything I should look out for?  I don't need the PLL actually, so if I can get the 9S12DJ64 running at 8 MHz bus without it, I'd be pleased.

2)  Can an 8 MHz bus 9S12DJ64 be controlled via the BDM by a 68HC912B32 eval board (also running at 8 MHz bus) with D-Bug12?

I attached the board schematic.  You can see how simple it is.  I'm only using 7 pins for I/O on the entire processor.


Thank you.