ST72F264

[shermantec]

Posted on July 15, 2005 at 04:59

ST72F264

[shermantec]

Posted on July 10, 2005 at 11:11

I would like to use the internal RC oscillator and also use SCI communication @4800baud.

I couldn't find in the datasheet the absolute min/max RC clock deviation between ST72264 devices.

I would like to know if it's safe to use the internal RC without preforming calibration for each device? (the other timing beside the SCI communication is negligible).

Thx

[torrey]

Posted on July 14, 2005 at 13:07

In section 6.2 (Multi-Oscillator) of the datasheet, it indicates that the RC oscillator has lower frequency accuracy.

In section 13.5.4 (RC Oscillators), it indicates that the internal frequency can vary from 2 to 6 MHz. Since this is a factor of 3 difference, I'm not sure if there is much hope for any SCI communication without calibration through the Baud Rate registers and/or Extended Prescalers.

It also looks like temperature can affect RC timing significantly, so you may want to make sure you are at operating temp before attempting calibration.

[fggnrc]

Posted on July 15, 2005 at 04:59

Latino,

even if ST72264 devices SCI are not LIN compatible, you could follow what LIN protocol suggests to syncronize clocks.

For instance, the sender may send a BREAK character whose duration is known. The ST2264 receiver could then measure this duration and set-up his local oscillator according to the result.

Then, the only thing that matters is the clock short-term stability.

I hope I was useful...

EtaPhi