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 [,page] )

 

 

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
page	A numeric variable or constant with the page address. Each page is 64 KB.

 

The similar Cpeek() function only works on the first 64 KB page. It was intended for processors with memory up to 64 KB.

When processors were made by Atmel with larger memory like the Mega128 (128 KB) the cpeekH() function was added.

The CpeekH() function uses the ELPM instruction instead of the LPM instruction that Cpeek() uses.

 

Since the memory is broken up in page of 64 KB, the cpeekH() function also access the memory in pages.

You can also omit the page number in which case the compiler will calculate the proper page address.

 

CpeekH(address,0) will work on the first page (first 64 KB)

CpeekH(address,1) will work on the second page (second 64 KB)

 

When omitting the page, the compiler will calculate and load the page register automatically.

 

 While the AVR uses word addresses since all instructions are 2 bytes long, the Cpeek() function uses a byte address. You need to take that in consideration with for example a boot loader address. The Atmel data sheet will only mention word addresses. For example boot loader address $1000 in the data sheet is $2000 and $2001 byte address for Cpeek().

See also

PEEK , POKE , INP , OUT

 

 

Example

'-----------------------------------------------------------------------------------------
'name : peek.bas
'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
$crystal = 4000000 ' 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 I As Integer , B1 As Byte
'dump internal memory
For I = 0 To 31 'only 32 registers in AVR
B1 = Peek(i) 'get byte from internal memory
Print Hex(b1) ; " ";
'Poke I , 1 'write a value into memory
Next
Print 'new line
'be careful when writing into internal memory !!
 
'now dump a part ofthe code-memory(program)
For I = 0 To 255
B1 = Cpeek(i) 'get byte from internal memory
Print Hex(b1) ; " ";
Next
'note that you can not write into codememory!!
 
Out &H8000 , 1 'write 1 into XRAM at address 8000
B1 = Inp(&H8000) 'return value from XRAM
Print B1
End

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