Specifications

BMA180
Preliminary data sheet
Bosch Sensortec
Rev. 1.0 Page 35 / - proprietary information - 06 March 2009
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Specifications within this document are preliminary and subject to change without notice. Document is not intended for publication.
7.9.1 adv_int
This bit is used to disable 3 advanced interrupt control bits: slope_alert, slope_int and st_damp.
If adv_int = 0, writing these advanced interrupt control bits to 1 has no effect on IC functions
(these bits are ignored). This feature is used to avoid IC mal-function when the above
mentioned advanced interrupt features shouldn’t be used but these bits are written to 1 by error.
adv_int
0
1
Functions of the bits are enabled
Advanced interrupt control bits
Can't be activated (writing them to 1 has no effect)
7.9.2 new_data_int
If this bit is set to 1, an interrupt will be generated when all three axes acceleration values are
new, i. e. BMA180 updated all acceleration values after latest serial read-out. Interrupt
generated from new data detection is a latched one; microcontroller has to write reset_INT at 1
after interrupt has been detected high. This interrupt is also reset by any acceleration byte read
procedure (read access to address 02h to 07h).
New data interrupt always occurs at the end of the Z-axis value update in the output register
(2.4kHz rate, if smp_skipping = ‘0’, at 2*bw rate, if smp_skipping = ‘1’). Following figure shows
two examples of X-axis read out and the corresponding interrupt generation.
Explanation of new data interrupt.
left side - read out command of x-axis prior to next x-axis conversion
→ new data interrupt after completion of current conversion cycle
after z-axis conversion
right side - read out of x-axis send after x-axis conversion
→ new data interrupt at the end of next period when x axis has been updated
Please refer to section 5.1 for more details.
Note: When using the I
2
C interface for data transfer, the data read out phase can be longer than
417µs (depending on I
2
C clock frequency and the amount of data transmitted). Starting a new
data read out sequence may lead to a situation where the new_data_int may not be cleared
right in time. This must be considered and taken care of properly.
T X Y Z
X-axis value read out
New data interrupt
X-axis value read out
New data interrupt
T X Y Z T X Y Z T X Y Z
X-axis value read out
New data interrupt
X-axis value read out
New data interrupt
T X Y Z T X Y Z
…