MC6450 Datasheet, PDF (51/90 Pages) List of Unclassifed Manufacturers – 6-Axis eCompass

MC6450 6-Axis e-Compass
Preliminary Datasheet
8.3 I2C Message Format
The device uses the following general format for writing to the internal registers. The I2C master
generates a START condition, and then supplies the device ID. The 8^th bit is the R/W# flag (write cycle
= 0). The device pulls SDA low during the 9^th clock cycle indicating a positive ACK. This means, from
an 8-bit point of view of an external I2C master, writes should be written to address(0x98 for
accelerometer) and reads will occur by reading address (0x99 for accelerometer).
The second byte is the 8-bit register address of the device to access, and the last byte is the data to
write.
I2C Master
(To Sensor)
I2C Slave
(From Sensor)
START
Device ID (4C)
R/W#
Register Address
Register Data to Write
Stop
S
10011000
R7 R6 R5 R4 R3 R2 R1 R0
D7 D6 D5 D4 D4 D2 D1 D0
P
ACK
ACK/NAK
ACK
ACK/NAK
ACK
ACK/NAK
Figure 29. I2C Message Format, Write Cycle, Single Register Write
In a read cycle, the I2C master writes the device ID (R/W# = 0) and register address to be read. The
master issues a RESTART condition and then writes the device ID with the R/W# flag set to ‘1’. The
device shifts out the contents of the register address.
I2C Master
(To Sensor)
START
Device ID (4C)
R/W#
S
10011000
Register Address
R7 R6 R5 R4 R3 R2 R1 R0
Restart
Device ID (4C)
R/W#
R
10011001
NAK
NAK
I2C Slave
(from Sensor)
ACK
ACK/NAK
ACK
ACK/NAK
ACK
ACK/NAK
D7 D6 D5 D4 D3 D2 D1 D0
Read Data Byte
Figure 30. I2C Message Format, Read Cycle, Single Register Read
STOP
P
The I2C master may write or read consecutive register addresses by writing or reading additional bytes
after the first access. The device will internally increment the register address.
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