Kinetis Microcontrollers中的主题 K60: External clock characteristics

K60: External clock characteristics

mike65535 — Mon, 05 Nov 2012 21:52:10 GMT

I'm trying to find a spec for the electrical requirements for providing an external clock to the K60.

I currently have a circuit that puts a sinewave on "EXTAL", a sinewave that has a DC component of about 0.8V and a pk-to-pk voltage of about 0.7V

I get intermittent hanging at this in bsp_cm

while ((MCG_S & MCG_S_IREFST_MASK) != 0x00U) /* Check that the source of the FLL reference clock is the external reference clock. */

{

}

making me suspicious of the clock.

Re: K60: External clock characteristics

JimDon — Mon, 05 Nov 2012 22:32:46 GMT

Read the data sheet:

http://cache.freescale.com/files/microcontrollers/doc/data_sheet/K60P144M120SF3.pdf?fpsp=1

Re: K60: External clock characteristics

mike65535 — Tue, 06 Nov 2012 13:37:15 GMT

I've seen that and it doesn't tell me what I need to know.

I'd like to know the peak-to-peak amplitude and the DC offset it can tolerate of an external clock signal provide on EXTAL.

For ex, must the clock go from, say 0.5V to 1.5 V, or say from 0.8V to 1.8V or what?

Re: K60: External clock characteristics

apanecatl — Tue, 13 Nov 2012 17:55:09 GMT

Hi Mike, here are the XTAL pin electrical specifications, depending on the oscillator mode (low power or high gain) the signal amplitude can be either .6V or VDD, the full table can be found in chapter 6.3.2 Oscillator electrical characteristics of the K60 datasheet: