© MCS Electronics, 1995-2007
COUNTER0 and COUNTER1
Action
Set or retrieve the internal 16 bit hardware register.
Syntax
COUNTER0 = var |
TIMER0 can also be used |
var = COUNTER0 |
|
COUNTER1 = var |
TIMER1 can also be used |
var = COUNTER1 |
|
CAPTURE1 = var |
TIMER1 capture register |
var = CAPTURE1 |
|
COMPARE1A = var |
TIMER1 COMPARE A register |
var = COMPARE1A |
|
COMARE1B = var |
TIMER1 COMPARE B register |
var = COMPARE1B |
|
PWM1A = var |
TIMER1 COMPAREA register. (Is used for PWM) |
var = PWM1A |
|
PWM1B = var |
TIMER1 COMPARE B register. (Is used for PWM) |
var = PRM1B |
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|
Remarks
Var |
A byte, Integer/Word variable or constant that is assigned to the register |
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or is read from the register. |
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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
© MCS Electronics, 1995-2007
Action
Returns a byte stored in code memory.
Syntax
var = CPEEK( address )
Remarks
Var |
Numeric variable that is assigned with the content of the program memory |
|
at |
|
address |
Address |
Numeric variable or constant with the address location |
|
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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
'----------------------------------------------------------------------------- |
|
------------ |
: peek.bas |
'name |
'copyright |
: (c) 1995-2005, MCS Electronics |
'purpose |
: demonstrates PEEk, POKE, CPEEK, INP and OUT |
'micro |
: Mega48 |
'suited for demo |
: yes |
'commercial addon needed |
: no |
'-----------------------------------------------------------------------------
------------
$regfile = "m48def.dat" |
' specify the used |
micro |
' used crystal |
$crystal = 4000000 |
frequency |
' use baud rate |
$baud = 19200 |
$hwstack = 32 |
' default use 32 |
for the hardware stack |
' default use 10 |
$swstack = 10 |
for the SW stack |
' default use 40 |
$framesize = 40 |
for the frame space |
|
Dim I As Integer , B1 As Byte |
|
'dump internal memory |
'only 32 registers |
For I = 0 To 31 |
in AVR |
'get byte from |
B1 = Peek(i) |
internal memory |
|
Print Hex(b1) ; " "; |
'write a value into memory |
'Poke I , 1 |
Next |
'new line |
Print |
'be careful when writing into internal memory !!
|
© MCS Electronics, 1995-2007 |
'now dump a part ofthe code-memory(program) |
For I = 0 To 255 |
'get byte from |
B1 = Cpeek(i) |
internal memory |
"; |
Print Hex(b1) ; " |
Next |
|
'note that you can not write into codememory!! |
Out &H8000 , 1 |
'write 1 into XRAM |
at address 8000 |
'return value from |
B1 = Inp(&H8000) |
XRAM |
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Print B1 |
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End |
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CPEEKH
Action
Returns a byte stored in upper page of code memory of micro with more then 64KB such as M103, M128.
Syntax
var = CPEEKH( address )
Remarks
Var |
Numeric variable that is assigned with the content of the program memory |
|
at |
|
address |
Address |
Numeric variable or constant with the address location |
|
|
CpeekH(0) will return the first byte of the upper 64KB.
Since the M103 has 64K words of code space the LPM nstruction can not access the 64 upper Kbytes.
The CpeekH() function peeks in the upper 64 KB.
This function should be used with the M103 or M128 only.
See also
PEEK , POKE , INP , OUT
Example
'----------------------------------------------------------------------------- |
|
------------ |
: peek.bas |
'name |
'copyright |
: (c) 1995-2005, MCS Electronics |
'purpose |
: demonstrates PEEk, POKE, CPEEK, INP and OUT |
'micro |
: Mega48 |
'suited for demo |
: yes |
'commercial addon needed |
: no |
'-----------------------------------------------------------------------------
------------
$regfile = "m48def.dat" |
' specify the used |
|
page -409- |
|
© MCS Electronics, 1995-2007 |
micro |
' used crystal |
$crystal = 4000000 |
frequency |
' use baud rate |
$baud = 19200 |
$hwstack = 32 |
' default use 32 |
for the hardware stack |
' default use 10 |
$swstack = 10 |
for the SW stack |
' default use 40 |
$framesize = 40 |
for the frame space |
|
Dim I As Integer , B1 As Byte
'dump internal memory
For I = 0 To 31 |
'only 32 registers |
in AVR |
'get byte from |
B1 = Peek(i) |
internal memory |
"; |
Print Hex(b1) ; " |
'Poke I , 1 |
'write a value into memory |
Next |
'new line |
Print |
'be careful when writing into internal memory !! |
'now dump a part ofthe code-memory(program) |
For I = 0 To 255 |
'get byte from |
B1 = Cpeek(i) |
internal memory |
"; |
Print Hex(b1) ; " |
Next
'note that you can not write into codememory!!
Out &H8000 , 1 |
'write 1 into XRAM |
at address 8000 |
'return value from |
B1 = Inp(&H8000) |
XRAM |
|
Print B1 |
|
End |
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CRC8
Action
Returns the CRC8 value of a variable or array.
Syntax
Var = CRC8( 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. |
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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
© 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.
;##### X = Crc8(ar(1) , 7) |
Ldi R24,$07 ; number of bytes |
Ldi R30,$64 |
; address of ar(1) |
Ldi R31,$00 ; load constant in register |
Rcall _Crc8 |
; call routine |
Ldi R26,$60 |
; address of X |
St X,R16 |
; store crc8 |
Example
$regfile = "m48def.dat" |
' specify the used |
micro |
' used crystal |
$crystal = 8000000 |
frequency |
' use baud rate |
$baud = 19200 |
$hwstack = 32 |
' default use 32 |
for the hardware stack |
' default use 10 |
$swstack = 10 |
for the SW stack |
' default use 40 |
$framesize = 40 |
for the frame space |
|
Config Com1 = Dummy , Synchrone = 0 , Parity = None , Stopbits = 1 , Databits = 8 , Clockpol = 0
