MCP4017/18/19
DS22147A-page 36
2009 Microchip Technology Inc.
5.2.9
I2C COMMAND PROTOCOL
The MCP4017/18/19 is a slave I2C device which
supports 7-bit slave addressing. The slave address
contains seven fixed bits.
Figure 5-9 shows the control
byte format.
5.2.9.1
Control Byte (Slave Address)
The Control Byte is always preceded by a START
condition. The Control Byte contains the slave address
consisting of seven fixed bits and the R/W bit.
Figure 5-9 shows the control byte format and
Table 5-2 shows
the I2C address for the devices.
FIGURE 5-9:
Slave Address Bits in the
I2C Control Byte.
TABLE 5-2:
DEVICE I2C ADDRESS
5.2.9.2
Hardware Address Pins
The MCP4017/MCP4018/MCP4019 does not support
hardware address bits.
5.2.10
GENERAL CALL
The General Call is a method that the Master device
can communicate with all other Slave devices.
The MCP4017/18/19 devices do not respond to
General Call address and commands, and therefore
the communications are Not Acknowledged.
FIGURE 5-10:
General Call Formats.
SA6 A5A4A3A2 A1A0 R/W A/A
Start
bit
Slave Address
R/W bit
A bit (controlled by slave device)
R/W = 0 = write
R/W = 1 = read
A = 0 = Slave Device Acknowledges byte
A = 1 = Slave Device does not Acknowledge byte
“0” “1” “0” “1” “1” “1” “1”
Device
I2C Address
Comment
MCP4017
‘0101111’
MCP4018
‘0101111’
MCP4019
‘0101111’
0
00 0
S
000 0
X
xxxx
Ax
x
0 A P
General Call Address
Second Byte
“7-bit Command”
Reserved 7-bit Commands (By I2C Specification - Philips # 9398 393 40011, Ver. 2.1 January 2000)
‘0000 011’b - Reset and write programmable part of slave address by hardware.
‘0000 010’b - Write programmable part of slave address by hardware.
‘0000 000’b - NOT Allowed
The Following is a “Hardware General Call” Format
0
000
S
0000
X
xx
A
xx1 A
General Call Address
Second Byte
“7-bit Command”
X
xxxx
xxX A P
n occurrences of (Data + A / A)
This indicates a “Hardware General Call”
MCP4016/7/8/9 will ignore this byte and
all following bytes (and A), until
a Stop bit (P) is encountered.