uPSD UART Mode0 Max Baud

wek1 · ‎2004-03-01

Posted on March 01, 2004 at 14:31

wek1 · ‎2011-05-17

Posted on May 17, 2011 at 11:58

Hi,

The uPSD321x datasheet states (table 45) that the max. baud rate of UART in mode0 is 1MHz (constraining the Xtal freq. to 12MHz).

I haven't seen this kind of constraint in other '51 clones.

Is this true?

Have a nice day!

Jan

sjo · ‎2011-05-17

Posted on May 17, 2011 at 11:58

In uart mode0 the Baud rate is defined as Osc/12 and is fixed, as far as I am aware this has always been the case on 8051.

Regards

sjo

wek1 · ‎2011-05-17

Posted on May 17, 2011 at 11:58

Yes, but what about the MAXIMUM baud rate?

Jan

jinguanghua · ‎2011-05-17

Posted on May 17, 2011 at 11:58

I have tested Modeo using uart0, I got 1Mhz.

wek1 · ‎2011-05-17

Posted on May 17, 2011 at 11:58

Yes, of course, this is what I expected (as other '51 clones work this way).

But why then the ''max. 1MHz'' in datasheet of uPSD321x Table 45, page62?

Jan

PS. FrankJ, what is your device? Could you try it also @ 40MHz?

wek1 · ‎2011-05-17

Posted on May 17, 2011 at 11:58

I don't quite understand:

- what was the Xtal frequency? 12MHz?

- did you try higher Xtal frequency? and mode0 baud was still 1MHz?

Jan

jinguanghua · ‎2011-05-17

Posted on May 17, 2011 at 11:58

I use 24M crystal on the board and uart 0 mode 0 mode, I got 2M speed.

jinguanghua · ‎2011-05-17

Posted on May 17, 2011 at 11:58

ST3234A, I don't have 40Mhz crystal on hand.