MA700GQ-P Datasheet, PDF (9/15 Pages) MPS Industries, Inc. – Angular Sensor for Position Control with Side-Shaft Positioning Capability

MA700
Angular Sensor for Position Control with
Side-Shaft Positioning Capability
sends the 8 MSB of the measured angle A(15:8). The
second byte is the content of the register under test.
After this transmission the MagAlpha will continue
delivering the usual 16-bit angles A (15:0).
Example
To check the content of the register 4 (0100), which
contains the 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
A(15:12)
A(11:8)
value
LSB
Z(11:4)
10. Output Signals
The raw data coming out of the conditioning blocks is
an absolute angle, between 0 and 360 deg. This angle is
coded on 16 bits, depending on the value of AF. The
absolute output is sent out digitally as serial data. The
other outputs, ABZ or UVW, are constructed from the
absolute angles.
Absolute - Serial
The bit order of the transmitted data is MSB first, LSB
last. The timing requirements are indicated in section 3.
Every 2µs a new data is transferred into the output
buffer. The master device connected to the MagAlpha
triggers the reading by pulling the 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. As the CS is low, the master can read the data
by sending clock pulses with a maximum frequency of
25 MHz. There is not any minimum frequency or
timeout. See Figure 11 for a simple reading of 16 bit
data.
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 several times the same
data point.
In some applications it is helpful to know how many
data updates occurred between two successive readouts
or if the same data points was read more than once. For
this purpose the user can read an 8-bit index attached to
the data .It allows keeping 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
refreshed. Using the index the user can detect a double
reading of the same data (same index), or how many
data points were skipped.
For reading the 8-bit index the master has to send
16 + 8 = 24 clock pulses (see Figure 12).
Figure 11: Timing Diagram for Simple SPI Readout
A full reading requires 16 clock pulses. The MA700
delivers:
MSB
A(15:8)
LSB
A(7:0)
In case the user needs less resolution, since the MSB is
sent first, he can read the angle by sending less than 16
pulses. For instance by sending only 8 pulses, the
Figure 12: Timing Diagram for SPI Angle + Index Readout
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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