A31316 datasheet(28/61 Pages) ALLEGRO

28 / 61 page

3D Magnetic Position Sensor IC

A31316

Allegro MicroSystems

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

SENT Sampling Time

The SENT output data is sampled 33 ticks prior to the start of

the SCN nibble. If beginning a new serial message, it is also

composed at this time. This is detailed in Figure 19. In the figure,

Data 1 and Data 5 are sent out. Others are discarded.

33 tTICK

sync

SCN Data nibbles CRC

Pause (op�onal)

sync

SCN

CRC

Pause (op�onal)

Tupdate

Internal sample �me of the sensor.

Sample �me of the SENT serial message, SCN, and data nibbles.

Serial message is only sampled a�er previous serial message was sent.

Registers

SENT output

Data 0

Data 1

Data 2

Data 3

Data 4

Data 5

Data 6

Data 7

Data 8

Data 9

Data nibbles

33 tTICK

Figure 20: SENT Frame Sample Timing

SENT Output Rate

The SENT output rate depends on the SENT mode. In regular

SENT, the frame length is defined by the frame contents. Using

SENT-Pause, the frame length is constant. The length of the

frames can be selected. There are four options for the frame

length settings. Using sent_frame_rate = 0, the shortest possible

pause-pulse that can achieve a fixed frame duration is used, with

the calculation shown in the table below. Using the options sent_

frame_rate = 1, 2 or 3, a fixed frame rate, measured in ms rather

than ticks, can be selected. Settings are detailed in Table 16.

Table 12: SENT frame duration, depending on

sent_frame_rate

Frame rate including pause pulse

3 data nibbles: frame length 210 ttick

4 data nibbles: frame length 228 ttick

6 data nibbles: frame length 282 ttick

0.5 ms

1.0 ms

2.0 ms

The output behavior for correct frame rate configurations can be

seen in Figure 210 below:

Selected frame length

SENT output

Selected frame length

sync

SCN Data nibbles CRC

Pause

sync

SCN Data nibbles CRC

Pause

Start request for the SENT serial message

Figure 21: SENT frame start depending on selected frame rate

If the frame rate is configured to be so high that a message is not

finished before the intended start of the next one, the start request

is discarded. Such a setting is shown in Figure 221.

Selected frame length

Start request for the SENT serial message

SENT output

sync

SCN Data nibbles CRC

Pause

sync

SCN Data nibbles CRC

Pause

Selected frame length

Figure 22: SENT frame start depending on selected frame rate, with sent_frame_rate defining a too fast frame rate setting

A31316 Datasheet(PDF) 28 Page - Allegro MicroSystems

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