SoundTraxx DSD-150/DSX Technical Reference - Manual (Page 6)

Address Mode Direct Mode
Register Mode Ops Mode Short Form
Paged Mode Ops Mode Long Form
6 Digital Sound Decoder Technical Reference
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CV 2
VSTART
Description
Vstart defines the initial voltage level applied to the motor at speed step 1 as a fraction of
available supply voltage:
bit 7 bit 0
D7 D6 D5 D4 D3 D2 D1 D0
D0-D7: Motor Start Voltage
Vstart may contain any value from 0 to 255 (0 - 0xFF).
The starting voltage applied to the motor may be computed as:
Starting Voltage = Supply Voltage X ——
where CV 2 is the contents of the Vstart register. A value of 0 corresponds to a zero starting
voltage and 255 corresponds to the maximum available voltage.
For speed steps greater than 1, the DSD will continue to sum the initial starting voltage level
into the throttle computations which has the effect of offsetting all points on a given speed
curve by the level set by Vstart as illustrated in the figure below.
Default value: 07
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
SPEED STEP
MOTOR VOLTAGE
100%
75%
50%
25%
0%
VSTART = 20
VSTART = 0
CV2
255