TMC2225 DATASHEET (Rev. 1.15 / 2023-FEB-16)
31
0X70: PWMCONF – VOLTAGE MODE PWM STEALTHCHOP
Bit Name
Function
Comment
17 pwm_freq1 PWM frequency
%00: fPWM=2/1024 fCLK
16 pwm_freq0 selection
%01: fPWM=2/683 fCLK
%10: fPWM=2/512 fCLK
%11: fPWM=2/410 fCLK
15 PWM_
User defined amplitude Velocity dependent gradient for PWM amplitude:
14 GRAD
gradient
PWM_GRAD * 256 / TSTEP
13
This value is added to PWM_AMPL to compensate for
12
the velocity-dependent motor back-EMF.
11
10
Use PWM_GRAD as initial value for automatic scaling to
9
speed up the automatic tuning process. To do this, set
8
PWM_GRAD to the determined, application specific value,
with pwm_autoscale=0. Only afterwards, set
pwm_autoscale=1. Enable StealthChop when finished.
Alternatively program the determined value to OTP. It
automatically will be loaded upon power up, even when
StealthChop becomes enabled right away.
7 PWM_
6 OFS
5
4
3
2
1
0
User defined amplitude
(offset)
Hint:
After initial tuning, the required initial value can be read
out from PWM_GRAD_AUTO.
User defined PWM amplitude offset (0-255) related to full
motor current (CS_ACTUAL=31) in stand still.
(Reset default=36)
Use PWM_OFS as initial value for automatic scaling to
speed up the automatic tuning process. To do this, set
PWM_OFS to the determined, application specific value,
with pwm_autoscale=0. Only afterwards, set
pwm_autoscale=1. Enable StealthChop when finished.
PWM_OFS = 0 will disable scaling down motor current
below a motor specific lower measurement threshold.
This setting should only be used under certain
conditions, i.e., when the power supply voltage can vary
up and down by a factor of two or more. It prevents
the motor going out of regulation, but it also prevents
power down below the regulation limit.
PWM_OFS > 0 allows automatic scaling to low PWM duty
cycles even below the lower regulation threshold. This
allows low (standstill) current settings based on the
actual (hold) current scale (register IHOLD_IRUN).
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