A1335 Datasheet, PDF (16/29 Pages) Allegro MicroSystems – Precision Hall-Effect Angle Sensor IC with I 2C, SPI, and SENT Interfaces

A1335
Precision Hall-Effect Angle Sensor IC
with I²C, SPI, and SENT Interfaces
SENT MESSAGE STRUCTURE
Data within a SENT message frame is represented as a series of
nibbles, with the following characteristics:
• Each nibble is an ordered pair of a low-voltage interval
followed by a high-voltage interval
• The low-voltage interval acts as the delimiting state which acts
as a boundary between each nibble. The length of this low-
voltage interval is fixed at 5 ticks.
• The high-voltage interval performs the job of the information
state and is variable in duration in order to contain the data
payload of the nibble
• The slew rate of the falling edge may be adjusted using the
SENT_DRIVER parameter.
The duration of a nibble is denominated in ticks. The period of
a tick is set by the SENT_TICK parameter. The duration of the
nibble is the sum of the low-voltage interval plus the high-voltage
interval.
The parts of a SENT message are arranged in the following
required sequence (see Figure 7):
1. Synchronization and Calibration: Flags the start of the
SENT message.
2. Status and Communication Nibble: Provides A1335 status
and the optional serial data determined by the setting of the
SENT_SERIAL parameter.
3. Data: Angle information and optional data.
4. CRC: Error checking.
5. Pause Pulse (optional): Fill pulse between SENT message
frames.
05
12
Ticks
Message
Signal
Voltage
Low High
Interval Interval
Nibble Data Value = 0000
05
27
Ticks
Message
Signal
Voltage
Low
Interval
High
Interval
Nibble Data Value = 1111
Table 4: Nibble Composition and Value
Quantity of Ticks
Low-
Voltage
Interval
High-
Voltage
Interval
Total
Binary
(4-bit)
Value
5
7
12
0000
5
8
13
0001
5
9
14
0002
Decimal
Equivalent
Value
0
1
2
Figure 6: General Value Formation for SENT
0000 (left), 1111 (right)
5
21
26
1110
14
5
22
27
1111
15
SENT_FIXED
SENT_FIXED
SENT_FIXED
SENT_FIXED
SENT_FIXED
SENT_FIXED
Nibble Name
56 ticks
Synchronization
and Calibration
12 to 27
ticks
Status and
Commun-
ication
12 to 27
ticks
Data 1
(MSB)
12 to 27
ticks
Data 6
t_SENT
Figure 7: General Format for SENT Message Frame
12 to 27
ticks
CRC
Pause
Pulse
(optional)
Allegro MicroSystems, LLC
16
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com