TMC262 参数 Datasheet PDF下载

TMC262 DATASHEET (Rev. 2.07 / 2013-FEB-14)

9

4

stallGuard2 Load Measurement

stallGuard2 provides an accurate measurement of the load on the motor. It can be used for stall

detection as well as other uses at loads below those which stall the motor, such as coolStep load-

adaptive current reduction. (stallGuard2 is a more precise evolution of the earlier stallGuard

technology.)

The stallGuard2 measurement value changes linearly over a wide range of load, velocity, and current

settings, as shown in Figure 4.1. At maximum motor load, the value goes to zero or near to zero. This

corresponds to a load angle of 90° between the magnetic field of the coils and magnets in the rotor.

This also is the most energy-efficient point of operation for the motor.

1000

stallGuard2

reading

900

800

700

600

500

400

300

200

100

0

10

20

30

40

50

60

70

80

90

100

Start value depends

on motor and

operating conditions

stallGuard value reaches zero

and indicates danger of stall.

This point is set by stallGuard

threshold value SGT.

Motor stalls above this point.

Load angle exceeds 90° and

available torque sinks.

motor load

(% max. torque)

Figure 4.1 stallGuard2 load measurement SG as a function of load

Two parameters control stallGuard2 and one status value is returned.

Parameter

SGT

Description

7-bit signed integer that sets the stallGuard2

threshold level for asserting the SG_TST output

and sets the optimum measurement range for

readout. Negative values increase sensitivity,

and positive values reduce sensitivity so more

torque is required to indicate a stall. Zero is a

good starting value. Operating at values below -

10 is not recommended.

Mode bit which enables the stallGuard2 filter for

more precision. If set, reduces the measurement

frequency to one measurement per four

fullsteps. If cleared, no filtering is performed.

Filtering

compensates

for

mechanical

asymmetries in the construction of the motor,

but at the expense of response time. Unfiltered

operation is recommended for rapid stall

detection. Filtered operation is recommended

for more precise load measurement.

Setting

0

+1… +63

-1… -64

Comment

indifferent value

less sensitivity

higher sensitivity

SFILT

0

1

standard mode

filtered mode

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