Re: [avr-gcc-list] Const array in bootloader section

[Marko Panger]

My board will interface to a system which is already developed and 
installed so my communication protocol is somewhat already defined and I 
can't implement my (new) error detection scheme.

I must use a 8 bit CRC checking scheme with the "CRC polynom" defined by
the other side of the system. A solution was to calculate the CRC by 
using a table, but I am unable to place the table (pre-defined constant 
array) in the bootloader section.

Any other idea how to put a defined array in the bootloader section ?

Anyway thanks !

marko

Reza Naima wrote:
> somewhat delayed, but check out http://www.reza.net/avr/ -- i've already
> gotten a uart based bootloader written -- and it supports a simple
> checksum as well.
>
> -r
>
> On Fri, Sep 26, 2003 at 12:47:14PM +0200, Marek Michalkiewicz sent me this...
>
> > On Fri, Sep 26, 2003 at 10:50:12AM +0200, Marko Panger AGB Lab wrote:
> >
> > > I am implementing a bootloader which will receive data over a standard UART.
> > > Because the board will be mounted in a very noisy environment I would like
> > > to compute a CRC over the received data. The CRC is computed by using a CRC
> > > table.
> >
> > Not exactly the answer to your question (how to put the CRC table
> > in the bootloader), but see <avr/crc16.h> for an efficient CRC-16
> > implementation.  See http://pdfserv.maxim-ic.com/en/an/app27.pdf
> > (pages 14-16) for some background how it works.
> >
> > No big tables, and no slow one-bit-at-a-time loops, just 23 words
> > and cycles - should be fine for use in a bootloader.  This CRC is
> > compatible with the MODBUS RTU (http://www.modbus.org/) protocol.
> >
> > Hope this helps,
> > Marek
> >
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