HCTL-1101 Datasheet, PDF(33/40 Page) AVAGO TECHNOLOGIES LIMITED – General Purpose Control ICs Position and Velocity Control Low Power CMOS

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HCTL-1101 Datasheet, PDF (33/40 Pages) AVAGO TECHNOLOGIES LIMITED – General Purpose Control ICs Position and Velocity Control Low Power CMOS

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The actual velocity is computed only in this algorithm and

stored in scratch registers R35H (MSB) and R34H

(LSB). There is no fractional component in the actual ve-

locity registers and they can be read in any order.

The controller tracks the command velocity continuously

until new mode command is given. The system behavior

after a new velocity command is governed only by the

system dynamics until a steady state velocity is reached.

Integral Velocity Mode

Flags: F0 Cleared

F3 Cleared

F5 Set to begin move

Registers Used:

R00H R00D

Function

Flag Register

R26H R38D Acceleration LSB

R27H R39D Acceleration MSB

R3CH R60D Command Velocity

Integral Velocity Control performs continuous veloc-

ity profiling which is specified by command velocity and

command acceleration. Figure 13 shows the capability of

this control algorithm.

The user can change velocity and acceleration any time

to continuously profile velocity in time. Once the speci-

fied velocity is reached, the HCTL-1101 will maintain that

velocity until a new command is specified. Changes be-

tween actual velocities occur at the presently specified

linear acceleration.

The command velocity is an 8-bit twoâs-complement

word stored in R3CH. The units of velocity are quadrature

counts/sample time.

The conversion from rpm to quadrature counts/sample

time is shown in equation 9. The Command Velocity regis-

ter (R3CH) contains only integer data and has no fractional

component.

While the overall range of the velocity command is 8 bits,

twoâs-complements, the difference between any two se-

quential commands cannot be greater than 7 bits in mag-

nitude (i.e., 127 decimal). For example, when the HCTL-

1101 is executing a command velocity of 40H (+64D),

the next velocity command must fall in the range of 7FH

(+127D), the maximum command range, C1H (-63D), the

largest allowed difference.

The command acceleration is a 16-bit scalar word stored

in R27H and R26H. The upper byte (R27H) is the integer

part and the lower byte (R26H) is the fractional part pro-

vided for resolution. The integer part has a range of 00H to

7FH. The contents of R26H are internally divided by 256 to

produce the fractional resolution.

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