MPC860 power up problem

[billy_huan]

When I power up the MPC860, the clkout pin will generate a clock switch from 40MHz to 13MHz over and over, which the extal clock source is 40MHz. The MODCK0 is "1" and MODCK1 is "0".

So why would such a case happen? The error hardware configration or the chip itself is bad.

B.R.

[billy_huan]

Although I solve the clcok problem, these still no any signals from the UART TXD pin.

The old design had been used for 5 years, the boot and software are the same, the hardware is just re-layout.

[alexander_yakov]

Could you please describe in more details, what was the exact root cause of the clkout problem?

If this root cause is somehow related to re-layout, than I'm quite sure the UART issue is also related to re-layout.

[alexander_yakov]

Could you please describe in more details what you mean by "generate a clock switch from 40MHz to 13MHz over and over"

Do you mean output clock switchs from 40MHz to 13MHz after the power on? Or the clock output remains stable, but the value switches from power-on to power-on cycles?

Do you have scope picture illustrating the problem?