AS5040 View Datasheet(PDF) - austriamicrosystems AG

Part Name

Description

Manufacturer

AS5040

10-Bit 360º Programmable Magnetic Rotary Encoder

austriamicrosystems AG 

AS5040 − Programming the AS5040

ams Datasheet

[v2-12] 2017-Jun-20

Zero Position Programming

Zero position programming is an OTP option that simplifies

assembly of a system, as the magnet does not need to be

manually adjusted to the mechanical zero position. Once the

assembly is completed, the mechanical and electrical zero

positions can be matched by software. Any position within a

full turn can be defined as the permanent new zero/index

position.

For zero position programming, the magnet is turned to the

mechanical zero position (e.g. the “OFF”-position of a rotary

switch) and the actual angular value is read.

This value is written into the OTP register bits Z9:Z0 (see

Figure 33) and programmed as described in Programming the

AS5040.

This new absolute zero position is also the new Index pulse

position for incremental output modes.

Note(s): The zero position value may also be modified before

programming, e.g. to program an electrical zero position that

is 180° (half turn) from the mechanical zero position, just add

512 to the value read at the mechanical zero position and

program the new value into the OTP register.

Repeated OTP Programming

Although a single AS5040 OTP register bit can be programmed

only once (from 0 to 1), it is possible to program other,

unprogrammed bits in subsequent programming cycles.

However, a bit that has already been programmed should not

be programmed twice. Therefore it is recommended that bits

that are already programmed are set to “0” during a

programming cycle.

Non-Permanent Programming

It is also possible to re-configure the AS5040 in a

non-permanent way by overwriting the OTP register.

This procedure is essentially a “Write Data” sequence (see

Figure 33) without a subsequent OTP programming cycle.

The “Write Data” sequence may be applied at any time during

normal operation. This configuration remains set while the

power supply voltage is above the power-on reset level (see 0).

See Application Note AN5000-20 for further information.

Analog Readback Mode

Non-volatile programming (OTP) uses on-chip zener diodes,

which become permanently low resistive when subjected to a

specified reverse current.

The quality of the programming process depends on the

amount of current that is applied during the programming

process (up to 130mA).

Page 35

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