1-Wire D/A-Wandler

[mat-sche]

Hi,

der DS2450 16bit 1Wire ADC kannst Du als Wandler nehmen. Diesen kannst Du Dir auch als kostenloses Sample von Michrochip zuschicken lassen. Mit diesem kannst Du eine Auflösung von 16 bit erreichen. Wichtig ist hier nur Dein Platinenlayout, dieses muss sehr genau und gut entwickelt sein , um eine gute Wandlung hinzubekommen (Rauschminimierung, Wandlergenauigkeit).
Hier ist mein verwendeter Code in Bascom:

Declare Sub Crc_get()
Const 1w_readmem = &HAA
Const 1w_writemem = &H55
Const 1w_convertch = &H3C
Const 1w_readrom = &H33
Const 1w_matchrom = &H55
Const 1w_skiprom = &HCC
Const 1w_searchrom = &HF0
Const 1w_conditsrc = &HEC
Const 1w_ovdrvskprom = &H3C
Const 1w_ovdrvmtchrom = &H69
Const 1w_vccoperation = &H40

1wreset                                                                                                                                               'reset the device
  1wwrite 1w_skiprom                                                                                                                                  'Skip ROM
  1wwrite 1w_writemem                                                                                                                                 'Write Memory
  1wwrite &H1C                                                                                                                                        'Write to 001C
  1wwrite &H00
  1wwrite 1w_vccoperation                                                                                                                             'VCC Operation keeps device active!!

  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                                                                                               'read dummy byte

 1wreset                                                                                                                                              'reset the device
  'Write to locations beginning at 00 08
  1wwrite 1w_skiprom                                                                                                                                  'Skip ROM
  1wwrite 1w_writemem                                                                                                                                 'Write Memory
  1wwrite &H08                                                                                                                                        'Write to 00 08
  1wwrite &H00


' Set up Channel A for 16 bit resolution
  1wwrite &H00                                                                                                                                        '16 bit resoultion
  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                                                                                               'read dummy byte
' 5.12 Volt range
  1wwrite &H00                                                                                                                                        '5.12 Volt Range
  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                                                                                               'read dummy byte

' Set up Channel B for 16 bit resolution
  1wwrite &H00                                                                                                                                        '16 bit resoultion
  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                                                                                               'read dummy byte
' 5.12 Volt range
  1wwrite &H01                                                                                                                                        '5.12 Volt Range
  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                                                                                               'read dummy byte
' Set up Channel C for 16 bit resolution
  1wwrite &H00                                                                                                                                        '16 bit resoultion
  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                                                                                               'read dummy byte
' 5.12 Volt range
  1wwrite &H01                                                                                                                                        '5.12 Volt Range
  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                                                                                               'read dummy byte

' Set up Channel D for 16 bit resolution
  1wwrite &H00                                                                                                                                        '16 bit resoultion
  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                                                                                               'read dummy byte
' 5.12 Volt range
  1wwrite &H01                                                                                                                                        '5.12 Volt Range
  Crc_get                                                                                                                                             'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)

'( Set up Channel C for output 1
  1wwrite &HC0                                                                  'Output Open/Output OFF C0 is OFF 80 is ON
  Crc_get                                                                       'Read in 2 bytes 16bits
 Crc_dummy = 1wread(1)                                                          'read dummy byte
' 5.12 Volt range
  1wwrite &H00                                                                  'Doesn't matter space keeper
  Crc_get                                                                       'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                         'read dummy byte

' Set up Channel D for output 0
  1wwrite &HC0                                                                  'Output Open/Output OFF
  Crc_get                                                                       'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)                                                         'read dummy byte
' 5.12 Volt range
  1wwrite &H00                                                                  'Doesn't matter space keeper
  Crc_get                                                                       'Read in 2 bytes 16bits
  Crc_dummy = 1wread(1)
')

'*******************************************************************************
 '------------------ D S 2 4 5 0 ---------------------
    1wreset                                                                                                                                           'reset the device

    1wwrite 1w_skiprom                                                                                                                                '&HCC Skip ROM
    1wwrite 1w_convertch                                                                                                                              '&H3C Begin Conversion
    1wwrite &H0F                                                                                                                                      'Convert Mask 0000|DCBA ie 0F=0000|1111
    1wwrite &H00                                                                                                                                      '0                                                                'Preset Mask Set=D Clear=d DdCcBbAa ie 55=0101|0101

    Crc_get                                                                                                                                           'Read in 2 bytes 16bits
    Waitms 6                                                                                                                                          'use formula to calculate exact duration for channels

    1wreset                                                                                                                                           'reset the device
    1wwrite 1w_skiprom                                                                                                                                'Skip ROM
    1wwrite 1w_readmem                                                                                                                                'Read Memory
    1wwrite &H00                                                                                                                                      'Read Channel A
    1wwrite &H00                                                                                                                                      'Address 0000 and 0001

    For I_x = 1 To 4

        Lowbyte(i_x) = 1wread(1)
        Highbyte(i_x) = 1wread(1)

        Waitms 5

        Adval_adc1 = Makeint(lowbyte(1) , Highbyte(1))                                                                                                'PSG 500
        Adval_adc2 = Makeint(lowbyte(2) , Highbyte(2))                                                                                                'CDG 45
        Adval_adc3 = Makeint(lowbyte(3) , Highbyte(3))                                                                                                'PCG 400
        Adval_adc4 = Makeint(lowbyte(4) , Highbyte(4))
        'Print Adval_adc1 ; Spc(3) ; Adval_adc2                                  'IKR

    Next

Leider gibt es den AD nicht in Dip Version, nur in SMD.

Gruß MAT