TMC4330A Datasheet | Document Revision 1.01 • 2017-JAN-12
Bow values BOW1…BOW4:
45/166
Bow Value Units
Bow values are unsigned 24-bit values without decimal places. They are defined per
default as pulses per second³ [pps³].
In case higher bow values are required for short and steep ramps, do as
follows:
Action:
Set direct_bow_val_en =1 (GENERAL_CONF register 0x00)
Result:
The parameters are defined as acceleration value change per clock cycle with 24-bit
unsigned decimal places with the MSB defined as 2-29.
The particular bow values BOW1, BOW2, BOW3, BOW4 are calculated as follows:
3
BOWx [pps3] = BOWx / 253 · fCLK
The maximum bow are as follows:
max(BOW1…4) [pps²] ≤ max(AMAX;DMAX) [pps²] · fCLK / 1024
In case direct_bow_val_en = 1, the maximum value is also limited to:
max(BOW1…4) ≤ 220
Overview of Minimum and Maximum Values:
Minimum and Maximum Values (Frequency Mode and in general)
Value Classes
Velocity
Acceleration
Bow
Clock
VMAX, VSTART, VSTOP,
VBREAK
AMAX, DMAX,
ASTART, DFINAL
BOW1, BOW2,
BOW3, BOW4
CLK_FREQ
Affected Registers
(fCLK)
Minimum Nominal
Value
Maximum Nominal
Value
3.906 mpps
8.388 Mpps
0.25 mpps2
1 mpps3
4.194 MHz
32 MHz
4.194 Mpps2
16.777 Mpps3
Velocity mode:
½ pulse · fCLK
Maximum Related
Value
Positioning mode:
¼ pulse · fCLK
max(AMAX;DMAX)
· fCLK / 1024
VMAX · fCLK / 1024
|VMAX| >
max(VSTART;VSTOP;VBREAK)
Table 18: Minimum and Maximum Values if Real World Units are selected
Minimum and Maximum Values for Steep Slopes (Direct Mode, example with fCLK =16MHz)
Value Classes
Acceleration (direct_acc_val_en =1)
Bow (direct_bow_val_en =1)
Affected Registers
Calculation
AMAX, DMAX, ASTART, DFINAL, DSTOP
BOW1, BOW2, BOW3, BOW4
bow[pps³] = (∆a/clk_cycle) / 253 · fCLK
a[pps²] = (∆v/clk_cycle) / 237 · fCLK
2
3
Minimum Nominal
Value
Maximum Nominal
Value
~1.86 kpps²
~1.95 Gpps²
~454.75 kpps³
~476.837 Gpps3
Maximum Related
Value
VMAX · 15625 Hz
max(AMAX;DMAX) · 15625 Hz
Table 19: Minimum and Maximum Values for Steep Slopes for fCLK =16MHz
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