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LPC2292 Bootloader maximal autobaudrate?

Started by alipowsky July 12, 2006
I understood, that the LPC2292 bootloader autodetects the Baudrate of
the connected terminal.
Does anybody has some info, how this is done in details, and which is
the maximum available baudrate, which can be detected by the bootloader.
My system runs on a 10 MHz xtal.

Thanks
Andreas

An Engineer's Guide to the LPC2100 Series

--- In l..., "alipowsky" wrote:
>
> I understood, that the LPC2292 bootloader autodetects the Baudrate of
> the connected terminal.
> Does anybody has some info, how this is done in details, and which is
> the maximum available baudrate, which can be detected by the bootloader.
> My system runs on a 10 MHz xtal.
>
> Thanks
> Andreas

If you are running Version 1.64 of Philips Boot loader, with 14.7456
MHz crystal the maximum standard baud rate is 230400.

Working backwards, I expect the maximum for 10MHz crystal is 156250.

Jaya

My questions pointed to the other direction:
Which is the maximum baudrate (not necessarily a standard baudrate)
which the LPC would be able to detect. This probably will depend on
the way how the LPC autodetects it and the xtal used (10 MHz in my case).
My apporach is to do bootloader communication with this maximum not
standard baudrate .

Andreas

--- In l..., "jayasooriah" wrote:
>
> --- In l..., "alipowsky" wrote:
> >
> > I understood, that the LPC2292 bootloader autodetects the Baudrate of
> > the connected terminal.
> > Does anybody has some info, how this is done in details, and which is
> > the maximum available baudrate, which can be detected by the
bootloader.
> > My system runs on a 10 MHz xtal.
> >
> > Thanks
> > Andreas
>
> If you are running Version 1.64 of Philips Boot loader, with 14.7456
> MHz crystal the maximum standard baud rate is 230400.
>
> Working backwards, I expect the maximum for 10MHz crystal is 156250.
>
> Jaya
>
--- In l..., "alipowsky" wrote:
>
> My questions pointed to the other direction:
> Which is the maximum baudrate (not necessarily a standard baudrate)
> which the LPC would be able to detect. This probably will depend on
> the way how the LPC autodetects it and the xtal used (10 MHz in my
case).
> My apporach is to do bootloader communication with this maximum not
> standard baudrate .
>
> Andreas

For Philips boot loader, the maximum baud rate corresponds to minimum
baud rate divisor value of 4. Hence for 10MHz crystal your maximum
would be 10,000,000/(16*4) = 156250 baud.

The reason for minimum divisor value 4 has to do how the it is
implemented in the Philips Boot Loader. An optimal implementation can
go down to divisor count of 1 and this makes the upper limit in your
case 625000 baud.

My loader (SILL) with 14.7456MHz crystal will auto baud to 921600.

Hope this helps.

Jaya

>
> My loader (SILL) with 14.7456MHz crystal will auto baud to 921600.
>

Can LPC go up to 921600 baud?
Last time I checked, 230400 was maximum. Beyond that PC was dropping
characters.
May be PC was not able to handle the speed.
Best Regards,

Mukund Deshmukh.
Beta Computronics Pvt Ltd
10/1, IT Park, Parsodi,
Nagpur-440022
Cell - 9422113746
--- In l..., Mukund Deshmukh wrote:
>
> >
> > My loader (SILL) with 14.7456MHz crystal will auto baud to 921600.
> > Can LPC go up to 921600 baud?
> Last time I checked, 230400 was maximum. Beyond that PC was dropping
> characters.
> May be PC was not able to handle the speed.

You are probably right Mukund in relation to PCs. The board I have
uses FTDI's FT232BM and is a VCP on the PC side.

Note that UART itself will work to 921600 baud with 14.7456 MHz xtal
with CPU clock same as xtal clock. However the auto baud
implementation will only work to at most 1/4 of this rate.

Jaya