sca3000-e05pwb VTI Hamlin, sca3000-e05pwb Datasheet - Page 12

• Manufacturer Part Number: sca3000-e05pwb
• Description: Sca3000 Series 3-axis Accelerometer
• Manufacturer: VTI Hamlin

2.5 Ring Buffer
2.5.1
2.5.2
2.5.2.1
VTI Technologies Oy
www.vti.fi
Description
Usage
Overflow condition
The SCA3000's Ring Buffer is a 192 acceleration data samples long (64 samples of 11 bit three
axis data) internal memory to relax the real-time operation requirements of the host processor. The
following parameters are configurable:
The ring buffer can be enabled by setting BUF_EN bit in MODE register to "1". After enabling the
buffer, acceleration data can be read from BUF_DATA register using decrement register read,
which is described in section 4.1.3.2 for SPI and 4.2.1.3 for I
Each measurement axis can be individually disabled by setting corresponding bits in BUF_X_EN,
BUF_Y_EN and BUF_Z_EN in OUT_CTRL register to "0".
Output data length can be changed from 11 bits to 8 bits by setting bit BUF_8BIT in MODE register
to "1". See section 3.3 for bit level descriptions.
The count of available data samples in output ring buffer can be read from BUF_COUNT register.
Register value is updated only when it is accessed over the SPI or I
Data shift out order is X,Y,Z. In 11 bit mode two bytes must be read to get all 11 bits out. In that
case, the MSB byte is 1
See section 2.7 for interrupt functionality details.
Acceleration data is available in X_LSB, X_MSB, Y_LSB, Y_MSB, Z_LSB and Z_MSB when the
ring buffer is enabled.
Overflow is detected from data ring buffer in same way as from the output registers. See section
2.2.2.1 for details.
1. Each measurement axis can be individually disabled. If measurement data from e.g. Y-axis
2. Buffer data length can be changed from 11 to 8 bits. In 8-bit
3. Ring buffer's input sample rate can be the same as the sensor's data rate or divided by 2
4. The Interrupt condition, when enabled, can be selected between two: interrupt in INT-pin
1. 11 bits data length, X&Y&Z axis enabled:
2. 11 bits data length, Y&Z axis enabled:
3. 8 bits data length, all axis enabled:
4. 8 bits data length, X&Z axis enabled:
5. 8 bits data length, Z axis enabled:
is not needed, available memory can be used for X- and Z-axis data.
using shorter read sequence.
or 4. When the divider is e.g. 2, only every 2
occurs when the buffer is 50% or 75% full.
X1_MSB, X1_LSB, Y1_MSB, Y1_LSB, Z1_MSB, Z1_LSB, X2_MSB, X2_LSB, ... latest
Z_LSB
Y1_MSB, Y1_LSB, Z1_MSB, Z1_LSB, Y2_MSB, Y2_LSB, Z2_MSB, Z2_LSB, Y3_MSB,
Y3_LSB, ..., latest Z_LSB
X1, Y1, Z1, X2, Y2, Z2,..., latest Z
X1, Z1, X2, Z2, X3, Z3, ..., latest Z
Z1, Z2, Z3, ... , latest Z
st
Doc.Nr. 8257300A.07
. Examples:
nd
acceleration data will be stored.
2
C interface.
2
C.
mode,
data can be read out
SCA3000 Series
Rev.A.07
12/ 43