BDU behaviour - IIS2DLPC

[KJose.1]

Hi
 

I would like to clarify the exact behaviour of the BDU function. According to the datasheet and application note, BDU should prevent the output registers from being updated until both the LSB and MSB have been read.

After enabling BDU, I repeatedly read only the LSB register without reading the corresponding MSB. However, I receive a new LSB value with each read. This means LSB is getting updated, eventhough the condition of reading both LSB and MSB is not fulfilled. Why acceleration data appears to update even though the corresponding MSB register has not been read?

I’m using the following notations to explain better.

 

Time	LSB	MSB
t1	L1	M1
t2	L2	M2
t3	L3	M3
t4	L4	M4

 

Could you please clarify whether the LSB is allowed to update while the MSB remains frozen? If so, when the MSB is eventually read, should it correspond to the first LSB value or to the latest LSB value? i.e. If i read LSB only 4 times and then read MSB, would it be M1 or M4?  Is the BDU behaviour identical when using different modes and digital interfaces?

Thank you in advance for your clarification.