ina219 datasheet

INA219
SBOS448G –AUGUST 2008–REVISED DECEMBER 2015 www.ti.com
Programming (continued)
8.5.5.1 Serial Bus Address
To communicate with the INA219, the master must first address slave devices through a slave address byte. The
slave address byte consists of seven address bits, and a direction bit indicating the intent of executing a read or
write operation.
The INA219 has two address pins, A0 and A1. Table 1 describes the pin logic levels for each of the 16 possible
addresses. The state of pins A0 and A1 is sampled on every bus communication and should be set before any
activity on the interface occurs. The address pins are read at the start of each communication event.
Table 1. INA219 Address Pins and Slave Addresses
A1 A0 SLAVE ADDRESS
GND GND 1000000
GND V
S+
1000001
GND SDA 1000010
GND SCL 1000011
V
S+
GND 1000100
V
S+
V
S+
1000101
V
S+
SDA 1000110
V
S+
SCL 1000111
SDA GND 1001000
SDA V
S+
1001001
SDA SDA 1001010
SDA SCL 1001011
SCL GND 1001100
SCL V
S+
1001101
SCL SDA 1001110
SCL SCL 1001111
8.5.5.2 Serial Interface
The INA219 operates only as a slave device on the I
2
C bus and SMBus. Connections to the bus are made
through the open-drain I/O lines SDA and SCL. The SDA and SCL pins feature integrated spike suppression
filters and Schmitt triggers to minimize the effects of input spikes and bus noise. The INA219 supports the
transmission protocol for fast (1- to 400-kHz) and high-speed (1-kHz to 2.56-MHz) modes. All data bytes are
transmitted most significant byte first.
8.5.6 Writing to and Reading from the INA219
Accessing a particular register on the INA219 is accomplished by writing the appropriate value to the register
pointer. Refer to Table 2 for a complete list of registers and corresponding addresses. The value for the register
pointer as shown in Figure 18 is the first byte transferred after the slave address byte with the R/W bit LOW.
Every write operation to the INA219 requires a value for the register pointer.
Writing to a register begins with the first byte transmitted by the master. This byte is the slave address, with the
R/W bit LOW. The INA219 then acknowledges receipt of a valid address. The next byte transmitted by the
master is the address of the register to which data will be written. This register address value updates the
register pointer to the desired register. The next two bytes are written to the register addressed by the register
pointer. The INA219 acknowledges receipt of each data byte. The master may terminate data transfer by
generating a START or STOP condition.
When reading from the INA219, the last value stored in the register pointer by a write operation determines
which register is read during a read operation. To change the register pointer for a read operation, a new value
must be written to the register pointer. This write is accomplished by issuing a slave address byte with the R/W
bit LOW, followed by the register pointer byte. No additional data are required. The master then generates a
START condition and sends the slave address byte with the R/W bit HIGH to initiate the read command. The
next byte is transmitted by the slave and is the most significant byte of the register indicated by the register
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