Rainbow-electronics DS2482-800 Bedienungsanleitung PDF herunterladen (Seite 17)

DS2482-800: Eight-Channel 1-Wire Master

17 of 22

Not Acknowledged by Master: At some time when receiving data, the master must signal an end of data to the

slave device. To achieve this, the master does not acknowledge the last byte that it has received from the slave. In

response, the slave releases SDA, allowing the master to generate the STOP condition.

Figure 10. I²C Timing Diagram

SCL

SDA

STOP START

BUF

HD:STA

LOW

HD:DAT

HIGH

SU:DAT

Repeated

START

SU:STA

HD:STA

SU:STO

Spike

Suppression

NOTE: Timing is referenced to V

ILMAX

and V

IHMIN

Writing to the DS2482

To write to the DS2482, the master must access the device in write mode, i.e., the slave address must be sent with

the direction bit set to 0. The next byte to be sent is a command code, which, depending on the command, may be

followed by a command parameter. The DS2482 will acknowledge valid command codes and expected/valid

command parameters. Additional bytes or invalid command parameters will never be acknowledged.

Reading from the DS2482

To read from the DS2482, the master must access the device in read mode, i. e., the slave address must be sent

with the direction bit set to 1. The read pointer determines the register that the master will read from. The master

may continue reading the same register over and over again, without having to re-address the device, e. g., to

watch the 1WB changing from 1 to 0. To read from a different register, the master must issue the Set Read Pointer

command and then access the DS2482 again in read mode.

I²C Communication—Legend

SYMBOL DESCRIPTION SYMBOL DESCRIPTION

S START Condition DRST Command "Device Reset", F0h

AD,0 Select DS2482 for Write Access WCFG Command "Write Configuration", D2h

AD,1 Select DS2482 for Read Access CHSL Command "Channel Select", C3h

Sr Repeated START Condition SRP Command "Set Read Pointer", E1h

P STOP Condition 1WRS Command "1-Wire Reset", B4h

A Acknowledged 1WWB Command "1-Wire Write Byte", A5h

A\ Not Acknowledged 1WRB Command "1-Wire Read Byte", 96h

(Idle) Bus Not Busy 1WSB Command "1-Wire Single Bit", 87h

<byte> Transfer of 1 Byte 1WT Command "1-Wire Triplet", 78h

1 2 ... 12 13 14 15 16 17 18 19 20 21 22

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