CMA3000-D0X VTI Hamlin, CMA3000-D0X Datasheet - Page 31

• Manufacturer Part Number: CMA3000-D0X
• Description: Cma3000-d0x Series 3-axis Accelerometer
• Manufacturer: VTI Hamlin

9
9.1 Acceleration data reading via I
9.1.1
VTI Technologies Oy
www.vti.fi
Known issues
Interrupt based acceleration reading
CMA3000-D01 has a design issue (to be corrected) related to acceleration data reading via I
bus: acceleration data reading during the INT-pin assertion (i.e. internal output register update)
causes the data corruption. The following sections discuss how to overcome this.
Interrupt (INT-pin) based acceleration data reading can be used only in measurement mode. After
interrupt signal activation the acceleration data has to be read before next interrupt activation. The
allowed reading time depends on selected measurement mode. Detailed timing values are
presented in Table 12 and Figure 24 below.
Table 12. CMA3000-D01 maximum reading periods in interrupt based acceleration data reading.
Output data rate
CMA3000-D01, MODE bits x10
ODR: 400Hz
CMA3000-D01, MODE bits x01
ODR: 100Hz
CMA3000-D01, MODE bits 011
ODR: 40Hz
ODR = Output Data Rate
Figure 24. Interrupt based CMA3000 acceleration data read timing.
If the above presented data read timing constraints are not met, the acceleration output data
should be ignored. Valid data samples can be read after the next interrupt signal.
INT-pin
Interrupt activation
Doc.Nr. 8281000.12
Reading period, T
2
C bus
Maximum reading
period, T
2.25 ms
22.5 ms
9.0 ms
r
r
Acceleration reading ends
Interrupt initialized
Interrupt activation
CMA3000-D0X Series
Rev. 0.12
31/ 35
2
C