8-bit MicrocontrollersのトピックCOP watchdog MCU S08AC

COP watchdog MCU S08AC

matri — Tue, 01 Apr 2008 20:25:13 GMT

Hello,

I'am developing firmware for an automatic electrical control burner, it must meet the IEC60730 class C, and I'm considering to use new MCU S08AC Freescale.
For me could be very interesting to select as clock source for the COP watchdog the internal 1KHz clock source. But, I need to find documents to demonstrate that this clock source is completely independent of any bus clock source.
Moreover, the COP counter is reset by writing any value in the read only SRS register. This act correspond to send a reset signal to the COP counter. How I can demonstrate this? In the data sheet are not showed COP block diagram.

Thanks a lot for any help or suggestion.

Marilena

Re: COP watchdog MCU S08AC

allawtterb — Tue, 01 Apr 2008 20:47:55 GMT

The datasheet does mention in a few places that the 1 kHz clock is seperate from any other clock. Take a look at section 5.7(Page 69) and section 5.9.7 (Page77) Table 5-10, the last field.

http://www.freescale.com/files/microcontrollers/doc/data_sheet/MC9S08AC16.pdf?pspll=1

Here are the quotes:

From sectoin 5.7:
The 1-kHz internal clock source is completely independent of any bus clock source and is used only by the RTI module and, on some MCUs, the COP watchdog.

From section 5.9.7:
The clock source for the real-time interrupt is a self-clocked source which oscillates at about 1 kHz, is independent of other MCU clock sources.

- Brett