Datasheet
11XX
DS22067J-page 10 2011 Microchip Technology Inc.
4.0 DEVICE COMMANDS
After the device address byte, a command byte must
be sent by the master to indicate the type of operation
to be performed. The code for each instruction is listed
in Table 4-1.
TABLE 4-1: INSTRUCTION SET
4.1 Read Instruction
The Read command allows the master to access any
memory location in a random manner. After the
READ
instruction has been sent to the slave, the two bytes of
the Word Address are transmitted, with an Acknowl-
edge sequence being performed after each byte. Then,
the slave sends the first data byte to the master. If more
data is to be read, the master sends a MAK, indicating
that the slave should output the next data byte. This
continues until the master sends a NoMAK, which ends
the operation.
To provide sequential reads in this manner, the 11XX
contains an internal Address Pointer which is incre-
mented by one after the transmission of each byte. This
Address Pointer allows the entire memory contents to
be serially read during one operation. When the highest
address is reached, the Address Pointer rolls over to
address ‘0x000’ if the master chooses to continue the
operation by providing a MAK.
FIGURE 4-1: READ COMMAND SEQUENCE
Instruction Name Instruction Code Hex Code Description
READ 0000 0011 0x03 Read data from memory array beginning at specified address
CRRD 0000 0110 0x06 Read data from current location in memory array
WRITE 0110 1100 0x6C Write data to memory array beginning at specified address
WREN 1001 0110 0x96 Set the write enable latch (enable write operations)
WRDI 1001 0001 0x91 Reset the write enable latch (disable write operations)
RDSR 0000 0101 0x05 Read STATUS register
WRSR 0110 1110 0x6E Write STATUS register
ERAL 0110 1101 0x6D Write ‘
0x00’ to entire array
SETAL 0110 0111 0x67 Write ‘
0xFF’ to entire array
7654
Data Byte 1
3210
7654
Data Byte 2
3210
7654
Data Byte n
3210
SCIO
MAK
MAK
NoMAK
11010100
Start Header
SCIO
Device Address
MAK
00
(1)
001010
MAK
Command
01000001
MAK
NoSAK
SAK
Standby Pulse
SCIO
SAK
15 14 13 12
Word Address MSB
11 10 9 8
MAK
SAK
7654
Word Address LSB
3210
MAK
SAK
SAK
SAK
SAK
Note 1: For the 11XXXX1, this bit must be a ‘1’.