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AS5245

Data Sheet - D e t a i l e d D e s c r i p t i o n

8.2 Synchronous Serial Interface (SSI)

Figure 5. Synchronous Serial Interface with Absolute Angular Position Data

If CSn changes to logic low, Data Out (DO) will change from high impedance (tri-state) to logic high and the read-out will be initiated.

Each subsequent rising CLK edge shifts out one bit of data.

The serial word contains 18 bits, the first 12 bits are the angular information D[11:0], the subsequent 6 bits contain system information,

about the validity of data such as OCF, COF, LIN, Parity and Magnetic Field status (increase/decrease).

8.2.1 Serial Data Contents

D11:D0 – Absolute angular position data (MSB is clocked out first).

OCF – (Offset Compensation Finished). Logic high indicates the finished Offset Compensation Algorithm.

COF – (Cordic Overflow). Logic high indicates an out of range error in the CORDIC part. When this bit is set, the data at D9:D0 is invalid. The

absolute output maintains the last valid angular value. This alarm may be resolved by bringing the magnet within the X-Y-Z tolerance limits.

LIN – (Linearity Alarm). Logic high indicates that the input field generates a critical output linearity. When this bit is set, the data at D9:D0 may still

be used, but can contain invalid data. This warning may be resolved by bringing the magnet within the X-Y-Z tolerance limits.

Even Parity – Bit for transmission error detection of bits 1…17 (D11…D0, OCF, COF, LIN, MagINC, MagDEC). Placing the magnet above the

chip, angular values increase in clockwise direction by default.

Data D11:D0 is valid, when the status bits have the following configurations:

Note:

MagInc=MagDec=1 is only recommended in YELLOW mode (see Table 8)

Table 7. Status Bit Outputs

OCF

COF

LIN

Mag INC

Mag DEC

Parity

10

0

00

Even checksum of bits

1:15

01

10

11

CSn

CLK

DO

Angular Position Data

Status Bits

1

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0 OCF COF LIN

Mag

INC

Mag

DEC

Even

PAR

818

1

D11

D10

D11