Problem on switching FEI or FEE mode into FBE mode

priyanto — Fri, 22 Sep 2006 04:25:35 GMT

Hi,

I'm working on the project that uses battery-operated PCB deploying freescale MC9S08GT60.

To save power in the normal mode, the PCB uses 32K external crystal oscillator in the FBE

(FLL Bypassed External) mode. However, during power on or reset, I use internal oscillator

in the FEI (FLL Engaged Internal) at 5.5MHz. The problem is that I still cannot switch the mode

from FEI to FBE in low frequency. It always ended up with 4.4 MHz clock.

Another approach, during power on or reset, I use FEE (FLL Engaged External) at 4.5 MHz

using external oscillator. It can switch to FBE at 48KHz, but it does not work reliably during

reset operation. Many times I have to hit the reset switch several times,or it does not work at all.

Can anybody have good advice or solution? I would appreciate if I can get the sample code.

Thanks.

-Priyanto.

8-bit MicrocontrollersのトピックProblem on switching FEI or FEE mode into FBE mode