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PCLK speeds

philip1
Associate II
Posted on April 20, 2005 at 06:50

PCLK speeds

4 REPLIES 4
philip1
Associate II
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
Associate II
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
Associate II
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
Associate II
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