Datasheet

DocID022729 Rev 3 23/70
L6472 Functional description
70
6.5 Absolute position counter
An internal 22-bit register (ABS_POS) keeps track of the motor motion according to the
selected step mode; the stored value unit is equal to the selected step mode (full, half,
quarter, etc.). The position range is from -2
21
to +2
21
-1 (µ) steps (see Section 9.1.1 on page
41).
6.6 Programmable speed profiles
The user can easily program a customized speed profile, independently defining
acceleration, deceleration, maximum and minimum speed values through the ACC, DEC,
MAX_SPEED and MIN_SPEED registers respectively (see Section 9.1.5 on page 42, 9.1.6
on page 42, 9.1.7 on page 43 and 9.1.8 on page 43).
When a command is sent to the device, the integrated logic generates the microstep
frequency profile that performs a motor motion compliant to speed profile boundaries.
All acceleration parameters are expressed in step/tick
2
and all speed parameters are
expressed in step/tick; the unit of measurement does not depend on selected step mode.
Acceleration and deceleration parameters range from 2
-40
to (2
12
-2) • 2
-40
step/tick2
(equivalent to 14.55 to 59590 step/s2).
Minimum speed parameter ranges from 0 to (2
12
-1) • 2
-24
step/tick (equivalent to 0 to 976.3
step/s).
Maximum speed parameter ranges from 2
-18
to (2
10
-1) • 2
-18
step/tick (equivalent to 15.25 to
15610 step/s).
Infinite acceleration/deceleration mode
When the ACC register value is set to max. (0xFFF), the system works in “infinite
acceleration mode”: acceleration and deceleration phases are totally skipped, as shown in
Figure 8.
It is not possible to skip the acceleration or deceleration phase independently.
Figure 8. Speed profile in infinite acceleration/deceleration mode