CRC8UNI

CRC8UNI

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Action

Returns the CRC value of a variable or array.

 

 

Syntax

Var = CRC8UNI( source , L)

 

 

Remarks

Var

The variable that is assigned with the CRC8 of variable source.

Source

The source variable or first element of the array to get the CRC8 of.

L

The number of bytes to check.

 

CRC is used in communication protocols to check if there are no transmission errors.

The CRC8 function in BASCOM is mainly intended to be used with 1WIRE.

 

The CRC8UNI uses the CCITT with polynome value 7.

 

noticeWhen you want to use a different polynome, you can override the default by defining a constant named CRC8_POLY

Const CRC8_POLY = &HAA 'use a different value

 

 

See also

CHECKSUM , CRC16, CRC16UNI , CRC32 , TCPCHECKSUM , CRCMB , CRC8

 

 

Example

'------------------------------------------------------------------------------
'name                     : crc8-16-32.bas
'copyright                : (c) 1995-2017, MCS Electronics
'purpose                  : demonstrates CRC
'micro                    : Mega48
'suited for demo          : yes
'commercial addon needed  : no
'------------------------------------------------------------------------------
 
$regfile = "m48def.dat"                                     ' specify the used micro
$crystal = 8000000                                         ' used crystal frequency
$baud = 19200                                               ' use baud rate
$hwstack = 32                                               ' default use 32 for the hardware stack
$swstack = 10                                               ' default use 10 for the SW stack
$framesize = 40                                             ' default use 40 for the frame space
 
 
Dim Ar(10) As Byte
Dim J As Byte
Dim W As Word
Dim L As Long
Dim S As String * 16
 
 
S = "123456789"
 
Ar(1) = 1
Ar(2) = 2
Ar(3) = 3
 
 
J = Crc8(ar(1) , 3)                                         'calculate value which is 216
j = Crc8Uni(ar(1) , 3)                                     'calculate unsing CCITT which is 72
W = Crc16(ar(1) , 3)                                       '24881
L = Crc32(ar(1) , 3)                                       '1438416925
 
'                  data , length, intial value , Poly, reflect input, reflect output
 
Print Hex(Crc16Uni(S , 9 , 0 , &H1021 , 0 , 0))             'CRC-CCITT (0x0000)   31C3
Print Hex(Crc16Uni(S , 9 , &HFFFF , &H1021 , 0 , 0))       'CRC-CCITT (0xFFFF)   29B1
Print Hex(Crc16Uni(S , 9 , &H1D0F , &H1021 , 0 , 0))       'CRC-CCITT (0x1D0F)   E5CC
Print Hex(Crc16Uni(S , 9 , 0 , &H8005 , 1 , 1))             'crc16                BB3D
Print Hex(Crc16Uni(S , 9 , &HFFFF , &H8005 , 1 , 1))       'crc16-modbus         4B37
 
End