PCLK speeds

philip1 · ‎2005-04-19

Posted on April 20, 2005 at 06:50

PCLK speeds

philip1 · ‎2005-04-19

Posted on April 19, 2005 at 12:04

I'm a bit confused about the maximum allowed clock rates in the STR710, with particular relevance to maximum baud rates on the serial ports.

In the Reference Manual there is a table with PCLK1 set to 20MHz and a maximum baud rate of 625kBaud. Reading the data sheet seems to say that MCLK can go to 50Mhz but PCLK can only go up to 33MHz (is that a recommended value or an absolute maximum value?)

Can you tell me what is the maximum recommended clock rate for PCLK1 and 2 and hence for the various peripheral devices?

Many Thanks

PhilipJ

Edited:

sorry I've just found the entry in your FAQ about the clock speeds so my question is now a bit simpler,

can you set the Baud Rate register UARTn_BR to 1 or is 2 the minimum value allowed (as per the tables in the reference manual)?

[ This message was edited by: philipj on 19-04-2005 15:45 ]

hichem2 · ‎2005-04-19

Posted on April 19, 2005 at 12:54

Hello all,

You are right RISC, and the 2 mentioned in the table of the reference manual is just an example ;)

Regards,

Hich

philip1 · ‎2005-04-19

Posted on April 19, 2005 at 14:58

Thanks moderators!!

What happens if you setup the chip for a 32MHz PCLK1 and put 1 in the register? according to the data sheet both conditions are legal and therefore should produce a baud rate of 2Mbits/sec.

Does the port somehow choose to work at 625kbaud or just it go into some fault condition?

Thanks for your help

philip1 · ‎2005-04-19

Posted on April 20, 2005 at 06:50

OK,

thanks for the help.

It's a bit disappointing because I really wanted 1Mbit/sec for a project that would use a mimimum of 40 ARM7s (maximum of 230!!) talking to each other on an RS485 bus. I will see if my update rates can work at 625kbits/sec.

thanks again