Datasheet

© 2011-2012 Microchip Technology Inc. DS22272C-page 49
MCP4706/4716/4726
6.0 MCP47X6 I
2
C COMMANDS
The I
2
C protocol does not specify how commands are
formatted, so this section specifies the MCP47X6’s I
2
C
command formats and operation.
The commands can be grouped into the following
categories:
• Write memory
• Read memory
• General Call commands
The supported commands are shown in Table 6-2.
Many of these commands allow for continuous
operation. This means that the I
2
C master does not
generate a Stop bit but repeats the required
data/clocks. This allows faster updates since the
overhead of the I
2
C control byte is removed. Table 6-1
shows the supported commands and the required
number of bit clocks for both single and continuous
commands.
Write commands, determined by the R/W bit = 0, use
up to three command codes bits (C2:C0) to determine
the write’s operation.
The Read command is strictly determined by the R/W
bit = 1. There are two formats of the command, one for
12-bit and 10-bit devices and a second for 8-bit
devices.
The General Call commands utilize the I
2
C
specification reserved General Call command address
and command codes.
6.0.1 ABORTING A TRANSMISSION
A Restart or Stop condition in an expected data bit
position will abort the current command sequence and
data will not be written to the MCP47X6.
TABLE 6-1: I
2
C COMMANDS - NUMBER
OF CLOCKS
Command
# of Bit
Clocks
(1)
Operation Mode
Write Volatile DAC Register
Command
(2)
Single 29
Continuous 18n + 11
Write Volatile Memory
Command
Single 38
Continuous 27n + 11
Write All Memory Command Single 38
Continuous 27n + 11
Write Volatile Configuration
Bits Command
Single 20
Continuous 9n + 11
Read Command (12 and
10-bit DAC Register)
(2)
Single 65
Continuous 54n + 11
Read Command
(8-bit DAC Register)
(2)
Single 47
Continuous 36n + 11
Note 1: “n” indicates the number of times the command
operation is to be repeated.
2: This command is useful to determine when an
EEPROM programming cycle has completed
(RDY/BSY
Status bit)
TABLE 6-2: MCP47X6 SUPPORTED COMMANDS
Command
Code
(Note 1) Command Name
Writes Volatile
Memory?
Writes
EEPROM
Memory?
Command
during
EEPROM
Write
Cycle?
Comment
C2 C1 C0 Config. DAC Config. DAC
00X
Write Volatile DAC Register
Command (Note 2)
PD1:PD0
only
Yes No No No Writes volatile power-down bits
so can also be used to exit a
power-down state.
010
Write Volatile Memory
Command
Yes Yes No No No
011
Write All Memory Command Yes Yes Yes Yes No
100Write Volatile Configuration
Bits Command
Yes No No No No
101
Reserved
N/A N/A N/A N/A
N/A
Reserved (Note 3)
110
111 N/A N/A N/A N/A Reserved (Note 3)
N/A
Read Command
N/A N/A N/A N/A
Yes Determined by R/W bit in I
2
C™
Control byte
General Call Reset N/A N/A N/A N/A No Determined by General Call
command byte after the I
2
C
General Call address.
General Call Wake-up
N/A N/A N/A N/A
No
Note 1: These bits are the MSb of the 2nd byte in the I
2
C Write command. See Figure 6-1 to Figure 6-4.
2: X = Don’t Care bit. This command format does not use C0 bit.
3: Device operation is not specified.