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TMC211 DATASHEET (V. 1.04 / January 7, 2005)
5.1.11 Reference Search / Position initialization
A stepper motor does not provide information about the actual position of the motor. Therefore it is
recommended to perform a reference drive after power-up or if a motor shutdown happened in case of
a problem. The RunInit command initiates the reference search. The RunInit command consists of a
Vmin and a Vmax parameter and also position information about the end of first and second motion.
(6.11.9 RunInit).
A reference drive consists of two motions (Figure 6: RunInit): The first motion is to drive the motor into
a stall position or a reference switch. The first motion is performed under compliance of the selected
Vmax and Vmin parameter and the acceleration parameter specified in the RAM. The second motion
has got a rectangular shape without an acceleration phase and is to drive the motor out of the stall
position or slowly towards the stall position again to compensate for the bouncing of the faster first
motion to stop as close to the stall position as possible. The maximum velocity of the second motion
equals to Vmin. After the second motion the actual position register is set to zero. Finally, the secure
position will be traveled to if it is enabled (different from the most negative decimal value of –1024).
Once the RunInit command is started it can not be interrupted by any other command except a
condition occurs which leads to a motor shutdown (See 5.1.10 Motor Shutdown Management) or a
HardStop command is received. Furthermore the master has to ensure that the target position of the
first motion is not equal to the actual position of the stepper motor and that the target positions of the
first and the second motion are not equal. This is very important otherwise the circuit goes into a
deadlock state. Once the circuit finds itself in a deadlock state only a HardStop command followed by a
GetFullStatus command will cause the circuit to leave the deadlock state.
Velocity V
[FS/s]
2nd Motion
1st Motion
Vmax
Vmin
Position X
[FS]
Pos1
Figure 6: RunInit
Pos2
5.1.12 Sleep Mode
When entering Sleep mode, the stepper-motor is driven to the secure position if the secure position is
enabled (SecPos[10:0] different from the most negative decimal value of –1024). Then the circuit is
completely powered down, apart from the LIN receiver which remains active to detect a dominant state
on the bus. In case sleep mode is entered while a motion is ongoing, a transition will occur towards
secure position as described above.
The Sleep mode can be entered in the following cases:
•
•
The circuit receives a LIN frame with identifier 0x3C and first data byte containing 0x00, as
required by LIN specification rev. 1.3.
The LIN bus remains inactive or is lost during more than 25000 LIN bit times (1.30s at 19.2 kbit/s).
The circuit will return to normal mode once a valid LIN frame is received while in the Sleep mode (this
valid frame can be addressed to another slave). For more information refer to 6.11.15 Sleep Mode on
page 45.
Copyright © 2004-2005 TRINAMIC Motion Control GmbH & Co. KG
TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
