1WSEARCHFIRST - Revision history

Admin: Created page with "= Action
= This statement reads the first ID from the 1wire bus into a variable(array).
2013-02-01T12:40:50Z

Created page with "= <span class="f_Header">Action</span><br/> = This statement reads the first ID from the 1wire bus into a variable(array). <span style="font-family: 'Arial'; color: #000000..."

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= <span class="f_Header">Action</span><br/> =

This statement reads the first ID from the 1wire bus into a variable(array).

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= <span class="f_Header">Syntax</span><br/> =

var2 = <span class="f_Syntax">1WSEARCHFIRST</span>()

var2 = <span class="f_Syntax">1WSEARCHFIRST</span>( port , pin)

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= <span class="f_Header">Remarks</span><br/> =
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var2

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A variable or array that should be at least 8 bytes long that will be assigned with the 8 byte ID from the first 1wire device on the bus.

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port

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The PIN port name like PINB or PIND.

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pin

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The pin number of the port. In the range from 0-7. Maybe a numeric constant or variable.

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The 1wireSearchFirst() function must be called once to initiate the ID retrieval process. After the 1wireSearchFirst() function is used you should use successive function calls to the [[1WSEARCHNEXT|1wSearchNext]] function to retrieve other ID's on the bus.

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A string can not be assigned to get the values from the bus. This because a null may be returned as a value and the null is also used as a string terminator.

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I would advice to use a byte array as shown in the example.

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The 1wirecount function will take 4 bytes of SRAM.

___1w_bitstorage , Byte used for bit storage :

lastdeviceflag bit 0

id_bit bit 1

cmp_id_bit bit 2

search_dir bit 3

___1wid_bit_number, Byte

___1wlast_zero, Byte

___1wlast_discrepancy , Byte

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= <span class="f_Header">ASM</span><br/> =

The following asm routines are called from mcs.lib.

_1wire_Search_First : (calls _1WIRE, _ADJUST_PIN , _ADJUST_BIT_ADDRESS)

Parameters passed : R24 : pin number, R30 : port , X : address of target array

Returns nothing.

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= <span class="f_Header">See also</span><br/> =

[[1WWRITE]] , [[1WRESET]] , [[1WREAD|1WREAD ]], [[1WSEARCHNEXT]], [[1WIRECOUNT]]

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= <span class="f_Header">Example</span><br/> =

<source lang="bascomavr">
'--------------------------------------------------------------------------------
'name : 1wireSearch.bas
'copyright : (c) 1995-2005, MCS Electronics
'purpose : demonstrates 1wsearch
'micro : Mega48
'suited for demo : yes
'commercial addon needed : no
'--------------------------------------------------------------------------------

$regfile = "m48def.dat"
$crystal = 4000000

$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

Config 1wire = Portb.0 'use this pin
'On the STK200 jumper B.0 must be inserted

'The following internal bytes are used by the scan routines
'___1w_bitstorage , Byte used for bit storage :
' lastdeviceflag bit 0
' id_bit bit 1
' cmp_id_bit bit 2
' search_dir bit 3
'___1wid_bit_number, Byte
'___1wlast_zero, Byte
'___1wlast_discrepancy , Byte
'___1wire_data , string * 7 (8 bytes)

'[DIM variables used]
'we need some space from at least 8 bytes to store the ID
Dim Reg_no(8) As Byte

'we need a loop counter and a word/integer for counting the ID's on the bus
Dim I As Byte , W As Word

'Now search for the first device on the bus
Reg_no(1) = 1wsearchfirst()

For I = 1 To 8 'print the number
Print Hex(reg_no(i));
Next
Print

Do
'Now search for other devices
Reg_no(1) = 1wsearchnext()
For I = 1 To 8
Print Hex(reg_no(i));
Next
Print
Loop Until Err = 1

'When ERR = 1 is returned it means that no device is found anymore
'You could also count the number of devices
W = 1wirecount()
'It is IMPORTANT that the 1wirecount function returns a word/integer
'So the result variable must be of the type word or integer
'But you may assign it to a byte or long too of course
Print W

'as a bonus the next routine :
' first fill the array with an existing number
Reg_no(1) = 1wsearchfirst()
' unremark next line to chance a byte to test the ERR flag
'Reg_no(1) = 2
'now verify if the number exists
1wverify Reg_no(1)
Print Err
'err =1 when the ID passed n reg_no() does NOT exist
' optinal call it with pinnumber line 1wverify reg_no(1),pinb,1

'As for the other 1wire statements/functions, you can provide the port and pin number as anoption
'W = 1wirecount(pinb , 1) 'for example look at pin PINB.1
End
</source><br/>{{Languages}}

[[Category:BASCOM_Language_Reference]]