Rainbow-electronics DS3903 Bedienungsanleitung PDF herunterladen (Seite 8)

DS3903

Triple 128-Position Nonvolatile

Digital Potentiometer

8 ______________________________________________________________________

word consists of 101000 binary followed by A0 then the

R/W bit. If the R/W bit is high, a read operation is initiat-

ed. If the R/W bit is low, a write operation is initiated.

For a device to become active, the value of A0 must be

the same as the hard-wired address pins on the

DS3903. Upon a match of written and hard-wired

addresses, the DS3903 outputs a zero for one clock

cycle as an acknowledge. If the address does not

match, the DS3903 returns to a low-power mode.

Write Operations

After receiving a matching device address byte with the

R/W bit set low, the device goes into the write mode of

operation. The master must transmit an 8-bit EEPROM

memory address to the device to define the address

where the data is to be written. After the byte has been

received, the DS3903 transmits a zero for one clock

cycle to acknowledge the memory address has been

received. The master must then transmit an 8-bit data

word to be written into this memory address. The

DS3903 again transmits a zero for one clock cycle to

acknowledge the receipt of the data byte. At this point,

the master must terminate the write operation with a stop

condition. The DS3903 then enters an internally timed

STOP

CONDITION

OR REPEATED

START

CONDITION

REPEATED IF MORE BYTES

ARE TRANSFERRED

ACK

START

CONDITION

ACK

ACKNOWLEDGEMENT

SIGNAL FROM RECEIVER

ACKNOWLEDGEMENT

SIGNAL FROM RECEIVER

SLAVE ADDRESS

MSB

SCL

SDA

R/W

DIRECTION

BIT

12 678 9 12 893–7

Figure 2. 2-Wire Data Transfer Protocol

SDA

SCL

HD:STA

LOW

HIGH

BUF

HD:DAT

SU:DAT

REPEATED

START

SU:STA

HD:STA

SU:STO

STOP START

Figure 3. 2-Wire AC Characteristics

1 2 3 4 5 6 7 8 9 10 11

Digital Potentiometer 1

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