What's capacitor for oscillator? MC9S08LC36

取消
显示结果 
显示  仅  | 搜索替代 
您的意思是: 

What's capacitor for oscillator? MC9S08LC36

1,784 次查看
cicciounico
Contributor III

Hi,
I use MC9S08LC36 with oscillator at 2MHz.
I must use the  micro at 3V but my Vcc can be less 3V (example 2.6V).
At 2.8V the oscillator don't run!
I suppose wrong capacitor (I have try 10pF and 18pF).
I have try to change ICGTRM but don't run!

It run only at 3V.
What's capacity I must insert with 2Mhz of oscillator?
Thanks

 

 

Added p/n to subject.



Message Edited by NLFSJ on 2009-01-22 08:55 AM
标签 (1)
0 项奖励
回复
3 回复数

567 次查看
cicciounico
Contributor III
Now work!
I have change oscillator from 2MHz to 32KHz.
Now at 2.4V work fine and the oscillator run it.

thanks.
0 项奖励
回复

567 次查看
cicciounico
Contributor III
Thanks!
The LVD is disable.
The reset is alwais high.
I have test my board with Vcc=2.8V and I have see XTAL (PTB1) alwais high. If I tap the pin of microcontroller with a finger the oscillator wakeup and it run then I suppose is the oscillator.
My supposition is wrong?
Vcc is not to low, is 2.8V.
Thanks again!
0 项奖励
回复

567 次查看
Lundin
Senior Contributor IV
I don't think this is related to the oscillator, and the cap values aren't all that critical. 18pF should work fine.

Instead I strongly suspect the low-voltage detection is reseting the circuit, as it should. This kicks at around 2.6V. Have you configured the LVD properly for lower voltages?

You should be able to easily determine if this is the problem or not, by checking the reset pin of the MCU with an oscilloscope.
0 项奖励
回复