S12 / MagniV Microcontrollers中的主题 Re: MC9S12C32 Oscillator problem

MC9S12C32 Oscillator problem

sfb — Wed, 24 Oct 2007 20:33:34 GMT

Hi,

I am using MC9S12C32 and there is a problem with oscillator. There is 10MHz external oscillator but controller works with its own self-clock. I am using pierce osc and pull-down the XCLKS with 4K7. I think there is a problem with clock quality checking. But I don't know how to resolve this problem. What can I do?

Re: MC9S12C32 Oscillator problem

Lundin — Thu, 25 Oct 2007 13:54:43 GMT

Hard to tell without knowing what your oscillator looks like. What are the values used for the components? Also, double-check the soldering of the crystal, that is a rather common problem.

Re: MC9S12C32 Oscillator problem

sfb — Thu, 25 Oct 2007 14:04:24 GMT

Oscillator value is 4MHz, Capacitor values 22pF (I tried variations - 15, 22, 33, 47). I use 1M parallel resistor. I use pierce osc. configuration. XCLKS is pulled low by 4K7. But I don't sure my reset condiguration:

I was using MCP 100 for supervisor bu that was mistake(because of push-pull style and its problem for BDM). So I removed it and pulled high reset pin by 1K2. Does it cause problem?

Re: MC9S12C32 Oscillator problem

sfb — Thu, 25 Oct 2007 16:10:54 GMT

Dear Lundin,

I think solved the problem. VDD1 was pulled high.I removed the connection with 5V and VDD1 now external osc. is working (20MHz). Thanks for your reply.

Re: MC9S12C32 Oscillator problem

Lundin — Thu, 25 Oct 2007 20:33:53 GMT

Vdd1 and Vdd2 are the internal 2.5 voltage used by the mcu. Nothing should be connected to them but a decoupling capacitor (100nF or so) tied to the internal ground Vss1, Vss2. There is proposition in the manual regarding the electrical layout for those pins, as well as the oscillator and PLL filter.