© MCS Electronics, 1995-2007

COUNTER0 and COUNTER1

Action

Set or retrieve the internal 16 bit hardware register.

Syntax

Remarks

Because the above 16 bit register pairs must be accessed somewhat differently than you may expect, they are implemented as variables.

The exception is TIMER0/COUNTER0, this is a normal 8 bit register and is supplied for compatibility with the syntax.

When the CPU reads the low byte of the register, the data of the low byte is sent to the CPU and the data of the high byte is placed in a temp register. When the CPU reads the data in the high byte, the CPU receives the data in the temp register.

When the CPU writes to the high byte of the register pair, the written data is placed in a temp register. Next when the CPU writes the low byte, this byte of data is combined with the byte data in the temp register and all 16 bits are written to the register pairs. So the MSB must be accessed first.

All of the above is handled automatically by BASCOM when accessing the above registers.

Note that the available registers may vary from chip to chip.

The BASCOM documentation used the 90S8515 to describe the different hardware registers.

CPEEK

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© MCS Electronics, 1995-2007

Action

Returns a byte stored in code memory.

Syntax

var = CPEEK( address )

Remarks

There is no CPOKE statement because you can not write into programmemory. Cpeek(0) will return the first byte of the file. Cpeek(1) will return the second byte of the binary file.

See also

PEEK , POKE , INP , OUT

Example

'-----------------------------------------------------------------------------

------------

'be careful when writing into internal memory !!

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Dim I As Integer , B1 As Byte

'dump internal memory

Next

'note that you can not write into codememory!!

CRC8

Action

Returns the CRC8 value of a variable or array.

Syntax

Var = CRC8( source , L)

Remarks

CRC8 is used in communication protocols to check if there are no transmission errors. The 1wire for example returns a crc byte as the last byte from it’s ID.

The code below shows a VB function of crc8

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© MCS Electronics, 1995-2007

Function Docrc8(s As String) As Byte Dim j As Byte

Dim k As Byte Dim crc8 As Byte crc8 = 0

For m = 1 To Len(s)

x = Asc(Mid(s, m, 1)) For k = 0 To 7

j = 1 And (x Xor crc8)

crc8 = Fix(crc8 / 2) And &HFF x = Fix(x / 2) And &HFF

If j <> 0 Then

crc8 = crc8 Xor &H8C End If

Next k Next

Docrc8 = crc8 End Function

See also

CHECKSUM , CRC16, CRC32 , TCPCHECKSUM

ASM

The following routine is called from mcs.lib : _CRC8

The routine must be called with Z pointing to the data and R24 must contain the number of bytes to check.

On return, R16 contains the CRC8 value. The used registers are : R16-R19, R25.

Example

Config Com1 = Dummy , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0

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© MCS Electronics, 1995-2007

Dim Ar(10) As Byte

Dim J As Byte

Ar(1) = 1

Ar(2) = 2

Ar(3) = 3

CRC16

Action

Returns the CRC16 value of a variable or array.

Syntax

Var = CRC16( source , L)

Remarks

CRC16 is used in communication protocols to check if there are no transmission errors. The 1wire for example returns a crc byte as the last byte from it’s ID.

Use CRC8 for the 1wire routines.

There are a lot of different CRC16 routines. There is no real standard since the polynomial will vary from manufacture to manufacture.

The equivalent code in VB is shown below. There are multiple ways to implement it in VB. This is one of them.

VB CRC16 Sample

Private Sub Command1_Click()

Dim ar(10) As Byte

Dim b As Byte

Dim J As Integer

ar(1) = 1 ar(2) = 2 ar(3) = 3

b = Docrc8(ar(), 3) ' call funciton Print b

'calculate value which is 216

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© MCS Electronics, 1995-2007

J = CRC16(ar(), 3) ' call function

Print J

End Sub

Function Docrc8(ar() As Byte, bts As Byte) As Byte Dim J As Byte

Dim k As Byte Dim crc8 As Byte crc8 = 0

For m = 1 To bts

x = ar(m)

For k = 0 To 7

J = 1 And (x Xor crc8)

crc8 = Fix(crc8 / 2) And &HFF x = Fix(x / 2) And &HFF

If J <> 0 Then

crc8 = crc8 Xor &H8C End If

Next k Next

Docrc8 = crc8 End Function

'*****************************************************************

Public Function CRC16(buf() As Byte, lbuf As Integer) As Integer Dim CRC1 As Long

Dim b As Boolean CRC1 = 0 ' init CRC

For i = 1 To lbuf ' for each byte CRC_MSB = CRC1 \ 256 crc_LSB = CRC1 And 255 CRC_MSB = CRC_MSB Xor buf(i)

CRC1 = (CRC_MSB * 256) + crc_LSB

For J = 0 To 7 Step 1 ' for each bit

CRC1 = shl(CRC1, b)

If b Then CRC1 = CRC1 Xor &H1021

Next J

Next i

CRC16 = CRC1

End Function

'Shift Left function

Function shl(n As Long, ByRef b As Boolean) As Long Dim L As Long

L = n

L = L * 2

If (L > &HFFFF&) Then b = True

Else

b = False End If

shl = L And &HFFFF& End Function

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© MCS Electronics, 1995-2007

See also

CHECKSUM , CRC8, CRC32 , TCPCHECKSUM

ASM

The following routine is called from mcs.lib : _CRC16

The routine must be called with X pointing to the data. The soft stack–Y must contain the number of bytes to scan.

On return, R16 and R17 contain the CRC16 value. The used registers are : R16-R19, R25.

Example

Config Com1 = Dummy , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0

Dim Ar(10) As Byte

Dim J As Byte

Dim W As Word

Dim L As Long

Ar(1) = 1

Ar(2) = 2

Ar(3) = 3

End

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© MCS Electronics, 1995-2007

CRC32

Action

Returns the CRC32 value of a variable.

Syntax

Var = CRC32( source , L)

Remarks

CRC32 is used in communication protocols to check if there are no transmission errors.

See also

CHECKSUM , CRC8, CRC16 , TCPCHECKSUM

Example

Config Com1 = Dummy , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0

Dim Ar(10) As Byte

Dim J As Byte

Dim W As Word

Dim L As Long

Ar(1) = 1

Ar(2) = 2

Ar(3) = 3

End

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