AVR-Chat

At 07:59 AM 10/03/2009, you wrote:
>#define UBRRVAL (((F_CPU/(USART_BAUDRATE*4UL)))) // using the double baud flag

>May want to try *8UL instead of *4UL for double speed. (usually *16)

I know you would NEVER have overlooked that in ASM.  ;-)


Regards

John Samperi

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On Mon, Mar 9, 2009 at 5:38 PM, John Samperi
<samperi@ampertronics.com.au> wrote:
> At 07:59 AM 10/03/2009, you wrote:
>>#define UBRRVAL (((F_CPU/(USART_BAUDRATE*4UL)))) // using the double baud flag
>
>>May want to try *8UL instead of *4UL for double speed. (usually *16)
>
> I know you would NEVER have overlooked that in ASM.  ;-)

The problem is that the equation I quoted IS giving me the right baud.
I don't know why..

David VanHorn wrote:
> On Mon, Mar 9, 2009 at 5:38 PM, John Samperi
> <samperi@ampertronics.com.au> wrote:
>   
>> At 07:59 AM 10/03/2009, you wrote:
>>     
>>> #define UBRRVAL (((F_CPU/(USART_BAUDRATE*4UL)))) // using the double baud flag
>>>       
>>> May want to try *8UL instead of *4UL for double speed. (usually *16)
>>>       
>> I know you would NEVER have overlooked that in ASM.  ;-)
>>     
>
> The problem is that the equation I quoted IS giving me the right baud.
> I don't know why..
>
>   
    Does the clock prescaler is correctly programmed?

    Mark Jordan

>    Does the clock prescaler is correctly programmed?

Prescaler?

I only see UBRRH and UBRRL.
Is there a prescaler between the UART and the Xtal in a M32?

David VanHorn wrote:
>>    Does the clock prescaler is correctly programmed?
>>     
>
> Prescaler?
>
> I only see UBRRH and UBRRL.
> Is there a prescaler between the UART and the Xtal in a M32?
>
>   
    Sorry, I thought it has one like the ATMega48.

    What is your exact baud rate using a 4MHz clock?

    Mark Jordan

>    Sorry, I thought it has one like the ATMega48.
>
>    What is your exact baud rate using a 4MHz clock?

I'll check it again in the morning, but I was getting good data with
the PC set to 115200, and the equation as quoted, with *2 instead of
*16