DS1820 - jak obsłużyć Search ROM [F0h] ?

[Badman]

W tej chwili dysponuje tylko 1 DS1820, lecz już nie długo będę miał drugi, dlatego wyprzedając fakty
Jak powinna prawidłowo wygladać obsługa polecenia Search ROM [F0h] ?

1. Master inicjalizuje 1-wire
2. Master wysyła F0h

i co dalej ? Napewno któryś z czujników odpowie 1-szy, zczytać 64 bity, a co później ?

[Pikczu]

Dalej będzie przysłowiowa D..a bo najpierw musisz wiedzieć czego tak naprawdę szukasz na tej magistrali.
Więc najpierw trzeba zapisać kolejno te czujniki do pamięci musisz zrobić szybką procedurę zapisywania np i chyba najlepiej do pamięci eeprom.
(zapisujesz je osobno podpinając do magistrali , nie zapomnij o opóźnieniu po zapisie pierwszego.
Jeśli tego nie zrobisz pierwszy przyłożony do magistrali zapisze się tak samo w "komórkach" przeznaczonych na drugi czujnik )
czyli np na podstawie mojego kodu (bez tego opóźnienia)

Kod: Zaznacz cały

Do                                                          'poczatek petli rejstracyjnej
Dsx(1) = 1wsearchfirst()                                    'szukaj ds na magistrali
If Err = 0 Then                                             'jesli znalazl ds-a
   Incr Ds_y                                                'zwieksz ds_y o 1
        Select Case Ds_y:                                   'w zaleznosci ktory to ds
   Case 1:                                                  'pierwszy ds
     For Index = 1 To 8                                     'zapisz jego dane do eeprom
     Eds1(index) = Dsx(index)
     Next Index                                             'i tak 8 razy
    
   Case 2:                                                  'dla ds-a 2
     For Index = 1 To 8                                     'zapisz jego dane do eeprom
     Eds2(index) = Dsx(index)
     Next Index                                             'i tak 8 razy
     
  
End If                                                      'koniec warunklu
Loop Until Ds_y = 2                                        'koniec petli liczącej do 2 czujników 

Return              

Teraz masz to zapisane w pamięci eeprom
po wystartowaniu procesora musisz prze pisać te dane z eeproma do zmiennej której będziesz używał

Kod: Zaznacz cały

For Index = 1 To 8
    Ds1(index) = Eds1(index)                                'czytaj numery z eeprom po właczeniu zasilania
    Ds2(index) = Eds2(index)                                'czytaj numery z eeprom po włączeniu zasilania
   
Next Index
     Index = 0 

np tak jak wyżej
Teraz jak już pewnie wiesz potrzebujesz opóźnienie minimum 750ms po wysłaniu komendy konwersi temperatury

Kod: Zaznacz cały

 1wreset
   1wwrite &HCC                                             'konwertuj  wszystkie  
   1wwrite &H44 

teraz po upływie minimum 750ms
możesz odczytać temperaturę z ds-ów

Kod: Zaznacz cały

1wreset
   1wwrite &H55    ' komenda match rom 
   1wwrite Ds1(1) , 8                                       'wysyłasz adres konkretnego układu 
   1wwrite &HBE                                               'komenda odczytu scraczpada 
   I1(1) = 1wread(2) ' i od razu zapisanie do zmiennej tablicowej 


   1wreset
   1wwrite &H55                    ' komenda match rom 
   1wwrite Ds2(1) , 8             'wysyłasz adres konkretnego układu                                   
   1wwrite &HBE                     'komenda odczytu skraczpada 
   I2(1) = 1wread(2)            ' i od razu zapisanie do zmiennej tablicowej 

Myślę że w miarę zrozumiale to przedstawiłem

[Badman]

Hmm. Piszę jak na razie w asemblerze.
Jak u Ciebie wygląda zawartość procedury 1wsearchfirst ?
W nocie do DS1820 po wydaniu F0h jest:

DS1820 Tx BIT 0
DS1820 Tx ~(BIT 0)
MASTER Tx BIT 0
↓
sprawdzenie czy zgadza się BIT 0 jeśli tak, to to samo dla bitu następnego, aż do BIT 63.

Jednak tej kombinacji nie rozumiem, może ktoś mi to wytłumaczyć ?

[Pikczu]

Niestety z asemblera wiem tylko tyle że jest. Więc nie bardzo umiem pomóc ale może ktoś inny coś podpowie.

[keruseykaryu]

W zasadzie cały proces masz w nocie opisany ze szczegółami.

Example of a ROM Search

The ROM search process is the repetition of a simple 3–step routine: read a bit, read the complement of the bit, then write the desired value of that bit. The bus master performs this simple, 3–step routine on each bit of the ROM. After one complete pass, the bus master knows the contents of the ROM in one device. The remaining number of devices and their ROM codes may be identified by additional passes.
The following example of the ROM search process assumes four different devices are connected to the same 1–Wire bus. The ROM data of the four devices is as shown:
ROM1 00110101...
ROM2 10101010...
ROM3 11110101...
ROM4 00010001...

The search process is as follows:
1. The bus master begins the initialization sequence by issuing a reset pulse. The slave devices respond by issuing simultaneous presence pulses.
2. The bus master will then issue the Search ROM command on the 1–Wire bus.
3. The bus master reads a bit from the 1–Wire bus. Each device will respond by placing the value of the first bit of their respective ROM data onto the 1–Wire bus. ROM1 and ROM4 will place a 0 onto the 1–Wire bus, i.e., pull it low. ROM2 and ROM3 will place a 1 onto the 1–Wire bus by allowing the line to stay high. The result is the logical AND of all devices on the line, therefore the bus master sees a 0. The bus master reads another bit. Since the Search ROM data command is being executed, all of the devices on the 1–Wire bus respond to this second read by placing the complement of the first bit of their respective ROM data onto the 1–Wire bus. ROM1 and ROM4 will place a 1 onto the 1–Wire, allowing the line to stay high. ROM2 and ROM3 will place a 0 onto the 1–Wire, thus it will be pulled low. The bus master again observes a 0 for the complement of the first ROM data bit. The bus master has determined that there are some devices on the 1–Wire bus that have a 0 in the first position and others that have a 1.
The data obtained from the two reads of the 3–step routine have the following interpretations:
00 There are still devices attached which have conflicting bits in this position.
01 All devices still coupled have a 0–bit in this bit position.
10 All devices still coupled have a 1–bit in this bit position.
11 There are no devices attached to the 1–Wire bus.

4. The bus master writes a 0. This deselects ROM2 and ROM3 for the remainder of this search pass, leaving only ROM1 and ROM4 connected to the
1–Wire bus.
5. The bus master performs two more reads and receives a 0–bit followed by a 1–bit. This indicates that all devices still coupled to the bus have 0’s as their second ROM data bit.
6. The bus master then writes a 0 to keep both ROM1 and ROM4 coupled.
7. The bus master executes two reads and receives two 0–bits. This indicates that both 1–bits and 0–bits exist as the third bit of the ROM data of the attached devices.
8. The bus master writes a 0–bit. This deselects ROM1 leaving ROM4 as the only device still connected.
9. The bus master reads the remainder of the ROM bits for ROM4 and continues to access the part if desired. This completes the first pass and uniquely identifies one part on the 1–Wire bus.
10.The bus master starts a new ROM search sequence by repeating steps 1 through 7.
11. The bus master writes a 1–bit. This decouples ROM4, leaving only ROM1 still coupled.
12.The bus master reads the remainder of the ROM bits for ROM1 and communicates to the underlying logic if desired. This completes the second ROM search pass, in which another of the ROMs was found.
13.The bus master starts a new ROM search by repeating steps 1 through 3.
14.The bus master writes a 1–bit. This deselects ROM1 and ROM4 for the remainder of this search pass, leaving only ROM2 and ROM3 coupled to the
system.
15.The bus master executes two read time slots and receives two zeros.
16.The bus master writes a 0–bit. This decouples ROM3, and leaving only ROM2.
17.The bus master reads the remainder of the ROM bits for ROM2 and communicates to the underlying logic if desired. This completes the third ROM search pass, in which another of the ROMs was found.
18.The bus master starts a new ROM search by repeating steps 13 through 15.
19.The bus master writes a 1–bit. This decouples ROM2, leaving only ROM3.
20.The bus master reads the remainder of the ROM bits for ROM3 and communicates to the underlying logic if desired. This completes the fourth ROM search pass, in which another of the ROMs was found.

Note the following:
The bus master learns the unique ID number (ROM data pattern) of one 1–Wire device on each ROM Search operation. The time required to derive the part’s unique ROM code is:
960 ms + (8 + 3 x 64) 61 ms = 13.16 ms
The bus master is therefore capable of identifying 75 different 1–Wire devices per second.

Teraz translate.google.pl i do dzieła.