Datasheet

L9942 SPI - control and status registers
Doc ID 11778 Rev 7 23/40
5 SPI - control and status registers
5.1 Register 0
The meaning of the different bits is as follows:
:
Table 14. Register 0
Bit
Phase counter Decay mode Slew rate Step mode DIR
12 11 10 9 8 7 6 5 4 3 2 1 0
Access r w r w r w r w r w r w r w r w r w r w r w r w r w
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0
Name P4 P3 P2 P1 P0 DM2 DM1 DM0 SR1 SR0 ST1 ST0 DIR
DIR This bit controls direction of motor movement. DIR=1 clockwise DIR=0 counter clockwise.
ST1 ST0 This bits controls step mode of motor movement (Figure 3).
00 Micro-stepping
01 Mini-stepping
10 Half-stepping
11 Full-stepping
SR1 SR0 This bit controls slew rate of bridge switches. See also parameter Table 13
DM2 DM1 DM0 This bits controls decay mode of output current (Figure 3).
000 Slow decay
001 Mixed decay, fast decay until T
MD
> 4 µs
010 Mixed decay, fast decay until T
MD
> 8 µs
011 Mixed decay, fast decay until current undershoot T
mc
=T
FT
+T
CC
100 Auto decay, fast decay without delay time
Auto decay uses mixed decay automatically
to reduce current for next step if required
(see Figure 3 down right).
101 Auto decay, fast decay until T
MD
> 4 µs
110 Auto decay, fast decay until T
MD
> 8 µs
111
Auto decay, fast decay until current
undershoot T
mc
P4 P3 P2 P1 P0 This bits control position of motor, e.g. 00000 step angle is 0°, 01111 step angle is 180 °.