M41ST85W_11 STMICROELECTRONICS [STMicroelectronics], M41ST85W_11 Datasheet - Page 15

• Manufacturer Part Number: M41ST85W_11
• Description: 3.0/3.3 V I2C combination serial RTC, NVRAM supervisor and microprocessor supervisor
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M41ST85W
2.2
Note:
Read mode
In this mode the master reads the M41ST85W slave after setting the slave address (see
Figure
address 'An' is written to the on-chip address pointer. Next the START condition and slave
address are repeated followed by the READ mode control bit (R/W=1). At this point the
master transmitter becomes the master receiver.
The data byte which was addressed will be transmitted and the master receiver will send an
acknowledge bit to the slave transmitter (see
only incremented on reception of an acknowledge clock. The M41ST85W slave transmitter
will now place the data byte at address An+1 on the bus, the master receiver reads and
acknowledges the new byte and the address pointer is incremented to An+2.
This cycle of reading consecutive addresses will continue until the master receiver sends a
STOP condition to the slave transmitter.
The system-to-user transfer of clock data will be halted whenever the address being read is
a clock address (00h to 07h). The update will resume either due to a stop condition or when
the pointer increments to a non-clock or RAM address.
This is true both in READ mode and WRITE mode.
An alternate READ mode may also be implemented whereby the master reads the
M41ST85W slave without first writing to the (volatile) address pointer. The first address that
is read is the last one stored in the pointer (see
Figure 9.
9). Following the WRITE mode control bit (R/W=0) and the acknowledge bit, the word
Slave address location
START
Doc ID 7531 Rev 11
1
1
SLAVE ADDRESS
0
Figure 10 on page
1
Figure 11 on page
0
0
0
R/W
A
AI00602
16). The address pointer is
16).
Operating modes
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