Data Sheet

AMIS−30543
http://onsemi.com
26
Ix
DIR
Iy
Ix
Iy
DIR
NXT1
NXT2
NXT3
NXT4
Halfstep
endpos
1/4
th
step
Change from lower to higher resolution
startpos
PC20070604.6
Iy
Ix
Iy
Ix
DIR
NXT1
NXT2
NXT3
DIR
endpos
Halfstep
1/8
th
step
Change from higher to lower resolution
startpos
Figure 12. NXT−Step Mode Synchronization
Left: Change from lower to higher resolution. The left−hand side depicts the ending half−step position during which a new
step mode resolution was programmed. The right−hand side diagram shows the effect of subsequent NXT commands on the
micro−step position.
Right: Change from higher to lower resolution. The left−hand side depicts the ending micro−step position during which a new
step mode resolution was programmed. The right−hand side diagram shows the effect of subsequent NXT commands on the
half−step position.
Note: It is advised to reduce the micro−stepping resolution only at micro−step positions that overlap with desired micro−step
positions of the new resolution.
Programmable Peak−Current
The amplitude of the current waveform in the motor coils
(coil peak current = I
max
) is adjusted by means of an SPI
parameter “CUR[4:0]” (see Table 12 SPI Control Parameter
Overview). Whenever this parameter is changed, the
coil−currents will be updated immediately at the next PWM
period. Figure 13 presents the Peak−Current and Current
Ratings in conjunction to the Current setting CUR[4:0].
2 9 15 250 CUR[4:0]
Peak Current
Current Range 0
CUR[4:0] = 0 −> 2
Current Range 1
CUR[4:0] = 3 −> 9
Current Range 2
CUR[4:0] = 10 −> 15
Current Range 3
CUR[4:0] = 16 −> 25
3090 mA
Figure 13. Programmable Peak−Current Overview
1205 mA
680 mA
305 mA