CMR3000-D0X VTI Hamlin, CMR3000-D0X Datasheet - Page 12

• Manufacturer Part Number: CMR3000-D0X
• Description: Cmr3000-d0x Block Diagram With Digital Spi And I 2 C Interface
• Manufacturer: VTI Hamlin

4.1.2
4.1.2.1
4.1.3
VTI Technologies Oy
Myllynkivenkuja 6
P.O. Box 27
FI-01621 Vantaa
www.vti.fi
Examples of SPI communication
Multiple slave devices in SPI bus
Example of register read
Figure 5. An example of SPI read communication.
address for the selected operation, which is defined by bit 7 (‘0’ = read ‘1’ = write), which is
followed by one zero bit. The later 8 bits in the MOSI line contain data for a write operation and are
‘don’t-care’ for a read operation. CMR3000 samples bits in from MOSI line on the rising edge of
SCK and bits out to MISO line on falling edge of SCK.
The first bits in MISO line are not defined bit (bit 1), fixed zero bit (bit 2), power reset status (bits 3-
5), fixed zero bit (bit6), fixed one bit (bit7) and fixed zero bit (bit8). The later 8 bits contain data for a
read operation. During the write operation, these data bits are zero.
For write commands, data is written into the addressed register on the falling edge of 16th SCK
pulse.
For read commands, data is latched into the internal SPI output register (shift register) on the 8th
rising edge of SCK. The output register is shifted out MSB first over MISO output.
When the CSB is high state between data transfers, the MISO line is in the high-impedance state.
Multiple read operation mode (decrement reading) is supported for angular rate output data
registers (0Ch...11h). Reading can be started from any of these registers and address is reduced
by one continuously. From register address 0Ch the address jumps to 11h.
An example of Z-axis angular read command is presented in Figure 5. The master gives the
register address to be read via the MOSI line: '11' in hex format and '010001' in binary format,
register name is Z_MSB. 7
The sensor replies to a requested operation by transferring the register content via MISO line. After
transferring the asked Z_MSB register content, the master gives next register address to be read:
'10' in hex format and '010000' in binary format, register name is Z_LSB. The sensor replies to the
requested operation by transferring the register content MSB first.
Since both SPI and I
of when the CMR3000 is connected to a SPI bus with multiple slave devices. In case of multiple
devices on same SPI bus, it's important to prevent MOSI_SDA pin changes during SCK_SCL pin
high state. If the MOSI_SDA pin state is changed when the SCK_SCL pin is in high state, the I
transmission is engaged, see Figure 6 below.
2
C interfaces are enabled by default, certain precautions should be taken care
Doc.Nr. 82112900.A.02
th
bit is set to '0' to indicate the read operation.
CMR3000-D0X Series
Rev. A.02
12/ 26
2
C