MLX90363 Datasheet, PDF (21/57 Pages) Melexis Microelectronic Systems – Triaxis® Magnetometer IC With High Speed Serial Interface

MLX90363
Triaxis® Magnetometer IC
With High Speed Serial Interface
14.6. Trigger Mode 2
The Trigger Mode 1 works without Sync pulses, as the GET1 command plays the role of a sync pulse.
When a delay between the regular message readback and the start of acquisition is needed, or when two
or more slaves should be triggered synchronously, the use of a sync pulse is required, and this is the
meaning of the Trigger Mode 2.
Principle: The master first enables the trigger mode 2 by issuing a GET2 command.
The master then sends a Sync Pulse, at the appropriate time, to initiate the magnetic field acquisition and
post-processing.
Finally the master reads the response message with a NOP or a GET2. The GET2 command re-initiates a
sync pulse triggered acquisition, whereas the NOP command would just allow the master to receive the
latest packet.
FW background
S
PI
S
PI
ASP
DSP
SPI
S
PI
S
PI
ASP DSP
SPI
S
PI
SPI HW
Get2
Sync
Puls
Get2
Sync
Puls
tRESync
tSyncFE
Get2
Figure 6 – Trigger Mode 2 – Single Slave Approach
A timing constraint between GET2 and the sync pulse (tRESync) should be met.
When this timing is smaller than the constraint, the sync pulse might not be taken in account, causing the
next GET2 to return a NTT packet.
GET1 and GET2/SyncPulse can be interlaced.
Multi-slave approach: The way of working described below fits the multi-slave applications where
synchronous acquisitions are important. GET2 commands are sent one after the other to the slaves. Then
the Sync Pulses are sent almost synchronously (very shortly one after the other).
Mode 2 in dual slave
FW1 backgrouPSnId
ASP DSP SPI
S
PI
ASP DSP SPI
S
PI
SPI HW1Get2
Get2
FW2
background
S
PI
ASP DSP SPI
S
PI
ASP DSP SPI
Get2
S
PI
SPI HW2
Get2
Sync
Puls
Get2
Sync
Puls
Get2 for Slave 1 and Get2 for Slave 2 do not overlap
Get2
Figure 7 – Trigger mode 2 - Multi-slave approach, example for two slaves
3901090363
Rev. 005
Page 21 of 57
Data Sheet
Jul/13