DS1683STR datasheet(18/21 Pages) MAXIM

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DS1683

Total-Elapsed-Time and Event Recorder with Alarm

Maxim Integrated

data. A NACK is used to terminate a read sequence or

as an indication that the device is not receiving data.

Byte Write: A byte write consists of 8 bits of information

transferred from the master to the slave (most significant

bit first) plus a 1-bit acknowledgement from the slave

to the master. The 8 bits transmitted by the master

are done according to the bit write definition and the

acknowledgement is read using the bit read definition.

Byte Read: A byte read is an 8-bit information transfer

from the slave to the master plus a 1-bit ACK or NACK

from the master to the slave. The 8 bits of information

that are transferred (most significant bit first) from the

slave to the master are read by the master using the bit

read definition, and the master transmits an ACK using

the bit write definition to receive additional data bytes.

The master must NACK the last byte read to terminate

communication so the slave returns control of SDA to

the master.

Slave Address Byte: Each slave on the I2C bus

responds to a slave address byte sent immediately

following a START condition. The slave address byte

contains the slave address in the most significant 7 bits

and the R/W bit in the least significant bit.

The DS1683’s slave address is D6h (1101 011R/W,

where R/W is 0). When the R/W bit is 0 (such as in D6h),

the master is indicating it will write data to the slave. If

R/W is set to a 1 (D7h in this case), the master is indicat-

ing it wants to read from the slave. See Figure 8.

If an incorrect (nonmatching) slave address is written,

the DS1683 assumes the master is communicating with

another I2C device and ignores the communication

until the next START condition is sent.

Memory Address: During an I2C write operation to the

DS1683, the master must transmit a memory address

to identify the memory location where the slave is to

store the data. The memory address is always the sec-

ond byte transmitted during a write operation following

the slave address byte.

I2C Communication

Writing a Single Byte to a Slave: The master must

generate a START condition, write the slave address

byte (R/W = 0), write the memory address, write the

byte of data, and generate a STOP condition. The mas-

ter must read the slave’s acknowledgement during all

byte write operations.

When writing to the DS1683, EEPROM is written fol-

lowing the STOP condition at the end of the write

command. To change the setting without changing the

EEPROM, terminate the write with a repeated START

condition before the next STOP condition occurs.

Using a repeated START condition prevents the tW

delay required for the EEPROM write cycle to finish.

For a write command, data is transferred after receiv-

ing a STOP.

Writing Multiple Bytes to a Slave: To write multiple

bytes to a slave, the master generates a START condi-

tion, writes the slave address byte (R/W = 0), writes the

memory address, writes up to 8 data bytes, and gener-

ates a STOP condition. The DS1683 writes 1 to 8 bytes

(one page or row) with a single write transaction. This is

internally controlled by an address counter that allows

data to be written to consecutive addresses without

transmitting a memory address before each data byte

is sent. The address counter limits the write to one

8-byte page (one row of the memory map). Attempts

to write to additional pages of memory without sending

a STOP condition between pages result in the address

counter wrapping around to the beginning of the pres-

ent row. For example, a 3-byte write starts at address

06h and writes 3 data bytes (11h, 22h, and 33h) to

three “consecutive” addresses. The result is that

addresses 06h and 07h would contain 11h and 22h,

respectively, and the third data byte, 33h, would be

written to address 00h. To prevent address wrapping

from occurring, the master must send a STOP condi-

tion at the end of the page, then wait for the bus-free

or EEPROM write time to elapse. Then the master can

generate a new START condition and write the slave

address byte (R/W = 0) and the first memory address

of the next memory row before continuing to write data.

Acknowledge Polling: Any time a EEPROM byte is

written, the DS1683 requires the EEPROM write time

(tW) after the STOP condition to write the contents of

the byte to EEPROM. During the EEPROM write time,

the device does not acknowledge its slave address

because it is busy. It is possible to take advantage

Figure 8. DS1683 I2C Slave Address

0R/W

MSB

LSB

READ/WRITE BIT

SLAVE ADDRESS

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