AS5311

Data Sheet

www.austriamicrosystems.com

Revision 1.01

13 - 23

A value of zero or close to zero indicates a missing magnet.

Figure 9: Synchronous Serial Interface with Magnetic Field Strength Data

0

1

0

0

0

0

M6

M5

M4

M3

M2

M1

M0

OCF COF

LIN

Mag

INC

Mag

DEC

Even

PAR

D11

1

18

8

Status Bits

Magnetic field strength data

CSn

DO

CLK

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, if CLK is high at the falling edge of CSn (Figure 8), the first 12 bits are the

absolute distance 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).

If CLK is low at the falling edge of CSn (Figure 9), the first 12 bits contain the magnitude information

(range = 00…7F hex) and the subsequent bits contain the status bits (see above)

7.3.1

Data Contents

D11:D0 absolute linear position data (MSB is clocked out first)

M11:M0 magnitude / magnetic field strength information (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 D11:D0 (likewise M11:M0) is invalid.

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 D11:D0 may still be used, but can contain invalid data. This warning can be

resolved by increasing the magnetic field strength.

Even Parity

bit for transmission error detection of bits 1…17 (D11…D0, OCF, COF, LIN, MagINC, MagDEC)

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

Table 4: Status Bit Outputs

OCF

COF

LIN

Mag

INC

Mag

DEC

Parity

0

0

0

1

1

0

1

0

0

1*)

1*)

even checksum of bits 1:15

*) MagInc=MagDec=1 is only recommended in YELLOW mode (see Table 5)