MA300GQ-P Datasheet, PDF (10/18 Pages) MPS Industries, Inc. – Angular Sensor for 3-Phase Brushless Motor Commutation and Position Control with Side-Shaft Positioning Capability

MA300
Angular Sensor for 3-Phase Brushless Motor
Commutation and Position Control with Side-Shaft
Positioning Capability
Read Back the Register Content
It might be helpful to check the content of a
register, for instance to verify that the
programming was successful. The user must send
the REGISTER READ command (0001), then the
4-bit address of the register being tested. The last
8 bits of the stream will be ignored. The user can
send for instance 0000 0000:
command reg. address MSB
value
LSB
0001 xxxx 00000000
The MagAlpha response is within the same
transmission. In the first byte (simultaneous to the
4-bit READ command and the 4-bit address), the
MagAlpha sends the 8 MSB of the measured
angle A(15:8). The second byte is the content of
the register being tested. After this transmission,
the MagAlpha continues delivering the usual 16-
bit angles A(15:0).
Example
To check the content of register 4 (0100), which
contains 8 MSB’s of the zero setting, send the
data:
command reg. address MSB
Value
LSB
0001 0100 00000000
Simultaneously the MagAlpha replies:
Angle Out
MSB
Value
LSB
A(15:12)
A(11:8)
Z(11:4)
10. Output Signals
The bit order of the transmitted data is MSB first,
LSB last. The timing requirements are indicated in
section 3. Every 2µs, new data is transferred into
the output buffer. The master device connected to
the MagAlpha triggers the reading by pulling CS
down. When a falling edge of the CS signal
occurs, the data remains in the output buffer until
the CS signal returns to logic 1. When the CS is
low, the master can read the data by sending
clock pulses with a maximum frequency of
25MHz. There is no minimum frequency or
timeout. See Figure 11 for a simple reading of 16-
bit data.
Figure 11: Timing Diagram for Simple SPI Readout
A full reading requires 16 clock pulses. The
MA300 delivers:
MSB
A(15:8)
LSB
A(7:0)
If the user needs less resolution (since the MSB is
sent first), they can read the angle by sending less
than 16 pulses. For instance, by sending only 8
pulses, the MagAlpha provides an 8-bit angle
without ambiguity over 360 deg:
MSB
LSB
A(15:8)
If the master triggers the reading faster than the
refresh rate, the MagAlpha may send the same
data point several times.
In some applications, it is helpful to know how
many data updates occur between two successive
readouts or if the same data points were read
more than once. For this purpose, the user can
read an 8-bit index attached to the data. This
keeps track of the precise time of measurement
without the need of precisely controlling the
readout time. This index runs from 0 to 255 and is
incremented by 1 each time the output buffer is
Monolithic Power Systems, Inc. | Gland, Switzerland | Tel: [phone] | [e-mail] | www.sensimatech.com
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Reserved. MA700 Rev 1.0 September 2014
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