PD-013-42 / TMCM-110-42 Manual (V1.24/2011-NOV-25)
16
Copyright © 2011, TRINAMIC Motion Control GmbH & Co. KG
7.2.1.12
Microstep resolution (Z)
The microstep resolution can be set by the user. It depends on the maximum resolution which differs in the
three chopper modes (see 7.3). The maximum resolution is divided by the parameter
Z
.
Parameter Z
Microstep resolution
SPI
PWM
Phase (default)
0
max resolution
64 *)
64
256
1
1/2 max
32 **)
32
128
2
1/4 max
16
16
64
3
1/8 max
8
8
32
4
1/16 max
4
4
16
5
1/32 max
2
2
8
6
1/64 max
1
1
4
Table 7.10: Adjustment of Microstep Resolution
*) Simulated microsteps, the actual microsteps of the motor are not improved.
**) Simulated microsteps, the actual microsteps are improves but do not reach 32 microsteps.
Example:
AZ 2
ENTER sets the microstep resolution to a quarter of the maximum resolution.
7.3
Chopper modes
7.3.1
Chopper mode 0 (SPI) / default mode
In this mode, the motor coil current is regulated on a chopper-cycle-by chopper-cycle bias. This is the
standard operation mode for most motor drivers. It brings a medium microstep resolution of 16 microsteps
and typically works well with most motors and a high range of supply voltage and motor current settings. A
resolution of up to 64 microsteps can be simulated but the motor precision is only slightly improved
compared to 16 microsteps and the same as with 32 microsteps.
The maximum supply voltage (V
S
) of the motor must not exceed 22-25 times the nominal motor voltage (V
N
),
regarding the multiplication of I
COIL, MAX
and R
MOTOR
. A higher value would lead to an excess of motor rating.
The minimum supply voltage has to be above two times the nominal motor voltage.
MOTOR
MAX
COIL
N
N
S
N
R
I
V
V
V
V
,
25
...
22
2
It uses a chopper frequency of about 36kHz.
7.3.2
Chopper mode 1 (PWM)
This mode is identical to the SPI mode, but it increases the microstep resolution at low velocities / stand
still.
MOTOR
MAX
COIL
N
N
S
N
R
I
V
V
V
V
,
25
...
22
2
7.3.3
Chopper mode 2 (PHASE)
This mode uses a different chopper scheme, which provides a very high microstep resolution and smooth
motor operation. Care has to be taken concerning the selection of motor and supply voltage:
The motor is chopped with 20kHz, and the coil sees a 50% duty cycle at full supply voltage when the coil
current is meant to be zero. This is only true for the average, but the motor still sees an alternating current
and thus an alternating magnetic field. Now, care has to be taken in order to keep this current to a value
