MC3630 Datasheet, PDF (28/83 Pages) –

MC3630 3-Axis Accelerometer
Preliminary Datasheet
I2C Message Format
NOTE: At least one I2C STOP condition must be present between samples in order for
the device to update the sample data registers.
The device uses the following general format for writing to the internal registers. The I2C
master generates a START condition, and then supplies the 7-bit device ID. The 8th bit is the
R/W# flag (write cycle = 0). The device pulls DIN_SDA low during the 9th clock cycle indicating
a positive ACK.
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
R/W#
Register Address
Register Data to Write
Stop
S
11011100
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 12. 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
R/W#
S
11011100
Register Address
R7 R6 R5 R4 R3 R2 R1 R0
Restart
Device ID
R/W#
R
11011101
NAK
NAK
STOP
P
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 13. I2C Message Format, Read Cycle, Single Register Read
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.
NOTE: See (0x0E) Feature Register 2 for address wrap details.
SPI Physical Interface
The device always operates as an SPI slave. An SPI master must initiate all communication
and data transfers and generate the SCK_SCL clock that synchronizes the data transfer. The
CSN pin must be pulled up to VDDIO when the SPI interface is not in use. The SPI interface
can operate in 3-wire or 4-wire mode.
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