STEVAL-MKI024V1 STMicroelectronics, STEVAL-MKI024V1 Datasheet - Page 19

• Manufacturer Part Number: STEVAL-MKI024V1
• Description: DEMO BOARD BASED ON LIS331DL
• Manufacturer: STMicroelectronics
• Series: MEMSr

Specifications of STEVAL-MKI024V1

• Design Resources: STEVAL-MKI024V1 Gerber Files STEVAL-MKI024V1 Schematics STEVAL-MKI024V1 Bill of Materials
• Sensor Type: Accelerometer, 3 Axis
• Sensing Range: ±2.3g, 9.2g
• Interface: SPI, USB
• Sensitivity: 72mg/digit
• Voltage - Supply: 5V, USB
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: LIS331DL
• Acceleration: 2 g, 8 g
• Sensing Axis: Triple Axis
• Output Type: Digital
• Interface Type: USB
• Silicon Manufacturer: ST Micro
• Silicon Core Number: LIS331DL
• Kit Application Type: Sensing - Motion / Vibration / Shock
• Application Sub Type: Accelerometer
• Kit Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-8719

LIS331DL
5.1.1
I
The transaction on the bus is started through a START (ST) signal. A START condition is
defined as a HIGH to LOW transition on the data line while the SCL line is held HIGH. After
this has been transmitted by the Master, the bus is considered busy. The next byte of data
transmitted after the start condition contains the address of the slave in the first 7 bits and
the eighth bit tells whether the Master is receiving data from the slave or transmitting data to
the slave. When an address is sent, each device in the system compares the first seven bits
after a start condition with its address. If they match, the device considers itself addressed
by the Master.
The Slave ADdress (SAD) associated to the LIS331DL is 001110xb. SDO/SA0 pad can be
used to modify less significant bit of the device address. If SDO pad is connected to voltage
supply LSb is ‘1’ (address 0011101b) else if SDO pad is connected to ground LSb value is
‘0’ (address 0011100b). This solution permits to connect and address two different
accelerometers to the same I
Data transfer with acknowledge is mandatory. The transmitter must release the SDA line
during the acknowledge pulse. The receiver must then pull the data line LOW so that it
remains stable low during the HIGH period of the acknowledge clock pulse. A receiver which
has been addressed is obliged to generate an acknowledge after each byte of data
received.
The I
protocol must be adhered to. After the start condition (ST) a slave address is sent, once a
slave acknowledge (SAK) has been returned, a 8-bit sub-address will be transmitted: the 7
LSb represent the actual register address while the MSB enables address auto increment. If
the MSb of the SUB field is 1, the SUB (register address) will be automatically incremented
to allow multiple data read/write.
The slave address is completed with a Read/Write bit. If the bit was ‘1’ (Read), a repeated
START (SR) condition will have to be issued after the two sub-address bytes; if the bit is ‘0’
(Write) the Master will transmit to the slave with direction unchanged.
the SAD+Read/Write bit pattern is composed, listing all the possible configurations.
Table 10.
Table 11.
Table 12.
2
Master
C operation
Slave
Master
Slave
Command
2
C embedded inside the LIS331DL behaves like a slave device and the following
Read
Read
Write
Write
ST
SAD+Read/Write patterns
Transfer when Master is writing one byte to slave
Transfer when Master is writing multiple bytes to slave
ST
SAD + W
SAD[6:1]
001110
001110
001110
001110
SAD + W
2
SAK
C bus.
SAD[0] = SDO/SA0
SAK
SUB
0
0
1
1
SAK
SUB
DATA
SAK
R/W
SAK
0
1
0
1
DATA
Table 10
00111001 (39h)
00111000 (38h)
00111011 (3Bh)
00111010 (3Ah)
DATA
Digital interfaces
SAD+R/W
SAK
explains how
SAK
SP
19/42
SP