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BMA255

Data sheet

Page 27

BST-BMA255-DS004-04 | Revision 1.1 | December 2013

Bosch Sensortec

third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice.

In latched mode an asserted interrupt status and the selected pin are cleared by writing ´1´ to

bit (0x21) reset_int. If the activation condition still holds when it is cleared, the interrupt status is

asserted again with the next change of the acceleration registers.

In the temporary mode an asserted interrupt and selected pin are cleared after a defined period

of time. The behaviour of the different interrupt modes is shown graphically in figure 6. The

timings in this mode are subject to the same tolerances as the bandwidths (see Table 1).

internal signal from

interrupt engine

interrupt output

non-latched

temporary

latched

latch period

Figure 6: Interrupt modes

Several interrupt engines can use either unfiltered or filtered acceleration data as their input. For

these interrupts, the source can be selected with the bits in register (0x1E). These are (0x1E)

int_src_data, (0x1E) int_src_tap, (0x1E) int_src_slo_no_mot, (0x1E) int_src_slope, (0x1E)

int_src_high, and (0x1E) int_src_low. Setting the respective bits to ´0´ (´1´) selects filtered

(unfiltered) data as input. The orientation recognition and flat detection interrupt always use

filtered input data.

It is strongly recommended to set interrupt parameters prior to enabling the interrupt. Changing

parameters of an already enabled interrupt may cause unwanted interrupt generation and

generation of a false interrupt history. A safe way to change parameters of an enabled interrupt

is to keep the following sequence: disable the desired interrupt, change parameters, wait for at

least 10ms, and then re-enable the desired interrupt.

4.7.2 Mapping to physical interrupt pins (inttype to INT Pin#)

Registers (0x19) to (0x1B) are dedicated to mapping of interrupts to the interrupt pins “INT1” or

“INT2”. Setting (0x19) int1_”inttype” to ´1´ (´0´) maps (unmaps) “inttype” to pin “INT1”.

Correspondingly setting (0x1B) int2_”inttype” to ´1´ (´0´) maps (unmaps) “inttype” to pin “INT2”.

Note: “inttype” to be replaced with the precise notation, given in the memory map in chapter 6.

Example: For flat interrupt (int1_flat): Setting (0x19) int1_flat to ´1´ maps int1_flat to pin “INT1”.

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