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[ARM] UART1 baudrate calculation for 12 MHz

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pigrabbit

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For LPC2148 controller how to find baudrate for 12Mhz:
How to find P value and M value & pclk, U1DLL. i need brief explanation. can anyone help me.....
 
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d123

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I wish I could help you as that is an interesting question and I could learn something from the answer.

To save people time, the datasheet is here (please correct if this is not the right datasheet):
 

KlausST

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Hi,

12 MBaud? Or is 12MHz the system clock frequency?

Klaus
 

alexan_e

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To save people time, the datasheet is here (please correct if this is not the right datasheet):

Actually that contains the general characteristics and electrical data. The details about registers are in the user manual

For LPC2148 controller how to find baudrate for 12Mhz:
How to find P value and M value & pclk, U1DLL. i need brief explanation. can anyone help me.....

Have you tried the user manual?
The PLL settings are described in sections 4.8.9 to 4.8.11

To experiment with UART you can download the code bundle located https://www.lpcware.com/content/nxp...pc213xlpc214x-peripherals-using-keils-μvision
It includes a UART example (and a library you can use).

You never mentioned the compiler you are using, the examples are for keil uvision.
 
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FvM

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I think alexan_e answered much more than you asked.

Now it's time for you to become familiar with the very basic LPC2148 system properties.

After reviewing the mentioned documents, you'll realize that you are dealing with at least three different clock frequencies:
- Fosc, the external crystal or oscillator frequency
- CCLK, the processor clock frequency, PLL generated in the range of 10 to 60 MHz
- PCLK, the peripheral clock frequency, divided CCLK, drives e.g. the UART

Instead of repeating 12 MHz like a mantra, find out what's the actual PCLK of your design.
 
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