ds2786 Maxim Integrated Products, Inc., ds2786 Datasheet - Page 21

• Manufacturer Part Number: ds2786
• Description: Ds2786 Standalone Ocv-based Fuel Gauge
• Manufacturer: Maxim Integrated Products, Inc.

Write Data Protocol
The write data protocol is used to write to register and shadow RAM data to the DS2786 starting at memory
address MAddr. Data0 represents the data written to MAddr, Data1 represents the data written to MAddr + 1 and
DataN represents the last data byte, written to MAddr + N. The master indicates the end of a write transaction by
sending a STOP or Repeated START after receiving the last acknowledge bit.
The MSB of the data to be stored at address MAddr can be written immediately after the MAddr byte is
acknowledged. Because the address is automatically incremented after the least significant bit (LSB) of each byte
is received by the DS2786, the MSB of the data at address MAddr + 1 is can be written immediately after the
acknowledgement of the data at address MAddr. If the bus master continues an auto-incremented write transaction
beyond address 4Fh, the DS2786 ignores the data. Data is also ignored on writes to read-only addresses and
reserved addresses, as well as a write that auto increments to the Function Command Register (address FEh).
Incomplete bytes and bytes that are Not Acknowledged by the DS2786 are not written to memory. As noted in the
Memory Section, writes to EEPROM locations modify the shadow RAM only.
Read Data Protocol
The Read Data protocol is used to read register and shadow RAM data from the DS2786 starting at memory
address specified by MAddr. Data0 represents the data byte in memory location MAddr, Data1 represents the data
from MAddr + 1 and DataN represents the last byte read by the master.
Data is returned beginning with the MSB of the data in MAddr. Because the address is automatically incremented
after the LSB of each byte is returned, the MSB of the data at address MAddr + 1 is available to the host
immediately after the acknowledgement of the data at address MAddr. If the bus master continues to read beyond
address FFh, the DS2786 outputs data values of FFh. Addresses labeled “Reserved” in the Memory Map (Table 3)
return undefined data. The bus master terminates the read transaction at any byte boundary by issuing a No
Acknowledge followed by a STOP or Repeated START.
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package
outline information, go to www.maxim-ic.com/DallasPackInfo.)
S SAddr W A MAddr A Data0 A Data1 A … DataN A P
S SAddr W A MAddr A Sr SAddr R A Data0 A Data1 A … DataN N P
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