DS1805 데이터 시트보기 (PDF) - Maxim Integrated

부품명

상세내역

제조사

DS1805

Addressable Digital Potentiometer

Maxim Integrated 

Addressable Digital Potentiometer

Following the START condition, the DS1805 monitors

the SDA bus checking the device type identifier being

transmitted. Upon receiving the 0101 address code

and appropriate device select bits, the slave device

outputs an acknowledge signal on the SDA line.

Command and Protocol

The DS1805’s command and protocol structure of the

DS1805 allows the user to read or write to both the

scratchpad and potentiometer registers. Figures 4 and

5 show the command structures for the part.

Potentiometer data values and control and command

values are always transmitted most significant bit

(MSB) first. During communications, the receiving unit

always generates the acknowledge.

Reading the DS1805

As shown in Figure 4, the DS1805 provides one read-

command operation. This operation allows the user to

read both potentiometers. Specifically, the R/W bit of the

control byte is set equal to a one for a read operation.

Communication to read the DS1805 begins with a START

condition that is issued by the master device. The control

byte from the master device follows the START condition.

Once the control byte has been received by the DS1805,

the part responds with an acknowledge. The read/write

bit of the control byte as stated should be set equal to

one for reading the DS1805.

When the master has received the acknowledge from the

DS1805, the master can then begin to receive poten-

tiometer wiper data. The value of the register-0 wiper

position will be the first returned from the DS1805. Once

the eight bits of the register-0 wiper position have been

transmitted, the master needs to issue an acknowledge,

unless it is the only byte to be read, in which case the

master issues a not acknowledge. If desired, the master

can stop the communication transfer at this point by issu-

ing the STOP condition. However, if the value of the

potentiometer-1 wiper position value is needed, commu-

Table 1. 2-Wire Command Words

COMMAND

COMMAND VALUE

Write Register-0

101010 01

Write Potentiometer-1 Register

101010 10

Write Both Registers

101011 11

nication transfer can continue by clocking the remaining

eight bits of the potentiometer-1 value, followed by a not

acknowledge. Final communication transfer is terminated

by issuing the STOP command. Figure 4 shows the flow

of the read operation.

Writing to the DS1805

Figure 5 shows a data flow diagram for writing the

DS1805. The DS1805 has three write-command opera-

tions. These include write reg-0, write pot-1, and write

reg-0/pot-1. The write reg-0 command allows the user to

write the value of scratchpad register-0 and as an option

the value of potentiometer-1. The write-1 command allows

the user to write the value of potentiometer-1 only. The

last write command, write-0/1, allows the user to write

both registers to the same value with one command and

one data value being issued.

All the write operations begin with a START condition.

Following the START condition, the master device issues

the control byte. The read/write bit of the control byte is

set to zero for writing the DS1805. Once the control byte

has been issued and the master receives the acknowl-

edgment from the DS1805, the command byte is trans-

mitted to the DS1805. As mentioned above, there exist

three write operations that can be used with the DS1805.

Figure 5 and Table 1 show the binary value of each write

command.

Package Information

For the latest package outline information, go to

www.maxim-ic.com/packages.

CONTROL

BYTE

MSB

LSB

MSB

0 1 0 1 A2 A1 A0 1

R/W = 1

DATA

BYTE

REG-0

OPTIONAL

DATA

BYTE

LSB

MSB

LSB

POT-1

Figure 4. 2-Wire Read Protocols

_____________________________________________________________________ 9

Share Link: