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UART CHR(0)

 
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medifa

Bascom Member



Joined: 19 Jun 2017
Posts: 1

PostPosted: Mon Jun 19, 2017 9:01 am    Post subject: UART CHR(0) Reply with quote

Hallo,

I have a problem with the UART on a ATMEGA128.
I`m trying the calculate a CRC checksum, but sometimes I receive a chr(0).
This character terminates the string so the calculated checksum doesnŽ t match.

What can I do?

Here is the code:

Code:

         for stringzaehler = 1 to 29
            if in_com2(stringzaehler)=0 then
               ergebnisstring=ergebnisstring + chr(000)
            else
               ergebnisstring = ergebnisstring + str(in_com2(stringzaehler))
            end if
         next stringzaehler
         er=crc16(ergebnisstring(), 29)

         lbyte = er and 255
         shift er,right,8
         hbyte = er and 255

 


(BASCOM-AVR version : 2.0.7.8 , Latest : 2.0.7.8 )
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Evert :-)

Bascom Expert



Joined: 18 Feb 2005
Posts: 2108

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PostPosted: Mon Jun 19, 2017 9:58 am    Post subject: Reply with quote

Don't work with strings but with array's.
You have to make you own receive routine that does something with the chr(0) and put the rest in the array.
Depends on you protocol of course if this can work.

Or determine the length of the string with LEN(mystring) and then calculate the crc over this length.


Ps have a look at HIGH and LOW function to split up the crc.
Ps ,ps or use overlay to split the word up in bytes.
Dim My_word As Word
Dim Low_byte As Byte At My_word Overlay
Dim High_byte As Byte At My_word + 1 Overlay

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