MCP79411 datasheet(35/60 Pages) MICROCHIP

35 / 60 page

 2010-2013 Microchip Technology Inc.

DS20002266E-page 35

MCP79410/MCP79411/MCP79412

FIGURE 9-2:

ACKNOWLEDGE TIMING

9.1.2

DEVICE ADDRESSING AND OPERATION

A control byte is the first byte received following the

Start condition from the master device (Figure 9-2).

The control byte consists of a control code; for the

MCP7941X this is set as ‘1010111X’ for read (0xAF)

and write (0xAE) operations for the EEPROM.

The control byte for accessing the SRAM and RTCC

registers are set to ‘1101111X’ (0xDF for a read, 0xDE

for a write). The RTCC registers and the SRAM share

the same address space.

The last bit of the control byte defines the operation to

be performed. When set to a ‘1’ a read operation is

selected, and when set to a ‘0’ a write operation is

selected. The next byte received defines the address of

the data byte (Figure 9-3). The upper address bits are

transferred first, followed by the Least Significant bits

(LSb).

Following the Start condition, the MCP7941X monitors

the SDA bus, checking the device type identifier being

transmitted. Upon receiving an ‘1010111X’ or

‘1101111X’ code, the slave device outputs an

Acknowledge signal on the SDA line. Depending on the

state of the R/W bit, the MCP7941X will select a read

or write operation.

FIGURE 9-3:

CONTROL BYTE AND ADDRESS SEQUENCE BIT ASSIGNMENTS

SCL

Transmitter must release the SDA line at this point

allowing the Receiver to pull the SDA line low to

acknowledge the previous eight bits of data.

Receiver must release the SDA line at this point

so the Transmitter can continue sending data.

Data from transmitter

SDA

Acknowledge

Bit

010

R/W

••

•

••

EEPROM CONTROL BYTE

ADDRESS BYTE

CONTROL

CODE

111

101

R/W

••

•

••

SRAM/RTCC CONTROL BYTE

ADDRESS BYTE

CONTROL

CODE

111

MCP79411 Datasheet(PDF) 35 Page - Microchip Technology

MCP79411 Datasheet(HTML) 35 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Datasheet Download

Link URL