12
TMC222 DATASHEET (V. 1.12 / March 7, 2011)
The amount of equivalent full steps during acceleration phase can be computed by the next equation:
2
2
min
−
V
max
V
N
step
=
2⋅ Acc
5.1.7 Position Ranges
Position information is coded by using two’s complement format. Depending on the stepping mode
(See 5.1.1) the position ranges are as listed in the following table:
Stepping Mode
Position Range
Full range excursion
Half-stepping
-4096…+4095
(-212…+212-1)
-8192…+8191
(-213…+213-1)
-16384…+16383
(-214…+214-1)
-32768…+32767
(-215…+215-1)
8192 half-steps
213
16384 micro-steps
1/4 micro-stepping
1/8 micro-stepping
1/16 micro-stepping
214
32768 micro-steps
215
65536 micro-steps
216
Table 6: Position Ranges
Target positions can be programmed via serial interface by using the SetPosition command (see
6.8.11). The actual motor position can be read by the GetFullStatus2 command (see 6.8.2).
5.1.8 Secure Position
The GotoSecurePosition command drives the motor to a pre-programmed secure position (see 6.8.4).
The secure position is programmable by the user. Secure position is coded with 11 bits, therefore the
resolution is lower than for normal positioning commands, as shown in the following table.
Stepping Mode
Half-stepping
Secure Position Resolution
4 half steps
1/4 micro stepping
1/8 micro stepping
1/16 micro stepping
8 micro steps (1/4th)
16 micro steps (1/8th)
32 micro steps (1/16th)
Table 7: Secure Position Resolution
5.1.9 External Switch SWI
Pin SWI (see Figure 1, on page 7) will attempt to source and sink current in/from the external switch
pin. This is to check whether the external switch is open or closed, resp. if the pin is connected to
ground or Vbat. The status of the switch can be read by using the GetFullStatus1 command. As long
as the switch is open, the <ESW> flag is set to zero.
The ESW flag just represents the status of the input switch. The SWI input is intended as a physical
interface for a mechanical switch that requires a cleaning current for proper operation. The SWI input
detects if the switch is open or connected either to ground or to Vbat. The SWI input is not a digital
logic level input. The status of the switch does not automatically perform actions as latching of the
actual position. Those actions have to be realized by the application software.
Important Hint: The SWI is not a logic level input as usual; it needs to be connected via 1K resistor
either to +VBAT or GND;
Copyright © 2004-2011 TRINAMIC Motion Control GmbH & Co. KG
TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
