Interfacing Programs for 8085
Short Description
8085 Programs...
Description
INTERFACING PROGRAMS FOR 8085
PROGRAM TO INTERFACE 16 LED’S TO 8255 PORTS AND DISPLAY THEM AS PER THE SPECIFIED PATTERN. 0
1
2
3
4
5
6
7
LA
1
0
1
0
1
0
1
0
AAH
LB
0
1
0
1
0
1
0
1
55H
THE PROGRAM BELOW IS USED TO DISPLAY PATTERN AS ABOVE AND CERTAIN SEQUENCES.
8000 8001 8002 8003 8004 8005 8006 8007 8008 8009 800A 800B 800C 800D 800E 800F 8010 8011 8012 8013 8014 8015
MVI A 80 OUT CW MVI A AA OUT PA CALL DLY CMA OUT PB CALL DLY MVI C 08 RRC OUT PB
3E 80 D3 43 3E AA D3 40 CD 00 85 2F D3 41 CD 00 85 0E 08 0F D3 41
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8016 8017 8018 8019 801A 801B 801C 801D 801E 801F 8020 8021 8022 8023 8024 8025 8026 8027 8028 8029 802A 802B 802C 802D
CALL DLY DCR C JNZ 8013 MVI A AA MVI C 08 RRC OUT PA CALL DLY DCR C JNZ 8021 JMP 8004
CD 00 85 0D C2 13 80 3E AA 0E 08 0F D3 40 CD 00 85 0D C2 21 80 C3 04 80
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INTERFACING 8085 TO DAC A)TO GENERATE SQUARE WAVEFORM TO GENERATE SQUARE WAVEFORM USING DAC JUST WE HAVE TO SEND TWO DIFFERENT VALUES TO DAC THAT IS FOR LOW LEVEL AND HIGH LEVEL AND A PROPER DELAY.THE DELAY DEFINES THE FREQUENCY OF SQUARE WAVE.THE PROGRAM IS AS FOLLOWS : 0000 0001 0002 0003 0004 0005 0006 0007 0008 0009 000A 000B 000C 000D 000E 000F 0010 0011
LXI SP8500 MVI A 80 OUT CW MVI A 00 OUT PA CALL DLY CMA JMP 0009
31 00 85 3E 80 D3 40 3E 00 D3 41 CD 00 85 2F C3 09 00
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B)
PROGRAM TO GENERATE TRIANGULAR WAVE USING DAC
0000 0001 0002 0003 0004 0005 0006 0007 0008 0009 000A 000B 000C 000D 000E 000F 0010 0011 0012 0013 0014 0015 0016 0017 0018 0019 001A 001B 001C 001D 001E
LXI SP8500 MVI A 80 OUT CW MVI A 00 OUT PA CALL DLY INR A CPI FF JNZ 0009 OUT PA DCR A CALL DLY JNZ 8014 JMP 8009
31 00 85 3E 80 D3 40 3E 00 D3 41 CD 00 85 3C FE FF C2 09 00 D3 41 3D CD 00 85 C2 14 00 C3 09
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001F 00 ; C)PROGRAM TO GENERATE SAWTOOTH WAVEFORM USING DAC 0000 0001 0002 0003 0004 0005 0006 0007 0008 0009 000A 000B 000C 000D 000E 000F 0010 0011
LXI SP8500 MVI A 80 OUT CW MVI A 00 OUT PA CALL DLY INR A JMP 0009
31 00 85 3E 80 D3 40 3E 00 D3 41 CD 00 85 3C C3 09 00
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D)PROGRAM TO GENERATE STAIRCASE WAVE USING DAC TO GENERATE STAIRCASE WAVEFORM IT IS REQUIRED TO CALUCLATE THE STEP SIZE. THE STEPSIZE IS CALUCLATED AS FOLLOWS : IF NUMBER OF STEPS = N THEN STEP SIZE = (MAX. AMPLITUDE / N) THE MAXIMMUM VALUE OF AN 8-BIT SYSTEM IS FFH. AND THE MAXIMUM AMPLITUDE IS 5V. SO FOR 5 STEPS THE STEPSIZE IS FF/N = 255/5 = 51 = 33H 0000 MVI A 80 3E 0001 80 0002 OUT CW D3 0003 40 0004 MVI A 00 3E 0005 0006 OUT PA 0007
000D JNC 000E 000F 0010 JMP 0004 0011
; ; ; ; ; 00 ; D3 ;
0006 06 ; 00 ; C3 ; 04 ;
41 ; 0008 CALL DLY 0009 000A 000B ADI 33 000C 33 ; D2 ;
CD 00 85 C6
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0012
00 ;
E) PROGRAM TO GENERATE EXPONENTIAL WAVEFORM USING DAC.
0000 0001 0002 0003 0004 0005 0006 0007 0008 0009 000A 000B 000C 000D 000E 000F 0010 0011 0012 0013 0014 0015 0016 0017 0018 0019 001A 001B
LXI SP8500 MVI A 80 OUT CW MVI A 00 STC RAL OUT PA CALL DLY CPI 40 JNZ 000A RAR OUT PA CALL DLY CPI 01
31 ; 00 ; 85 ; 3E ; 80 ; D3 ; 40 ; 3E ; 00 ; 37 ; 17 ; D3 ; 41 ; CD ; 00 ; 85 ; FE ; 40 ; C2 ; 0A ; 00 ; 1F ; D3 ; 41 ; CD ; 00 ; 85 ; FE ;
001C 001D JNZ 0015 001E 001F 0020 JMP 000A 0021 0022
01 C2 15 00 C3 0A 00
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F) PROGRAM TO GENERRATE SINUSOIDAL WAVE USING DAC. TO GENERATE SINUSOIDAL WAVEFORM WE USE LOOKUP TABLE METHOD. LET Vθ = VPSINθ + VO IF WE SELECT THE AVERRAGE VALUE OF THE SINE WAVE (THAT IS θ = 0O) AT THE MIDDLE OF THE AVAILABLE RANGE THE WAVEFORM CAN BE OF MAXIMUM POSSIBLE AMPLITUDE. THE FULL SWING IS LIMITED TO FFH IN AN 8-BIT SYSTEM. IF AVERAGE LEVEL V0IS SELECTED TO BE 80H THE VP (PEAK EXCURSION) CAN BE FFH – 80H = 7FH. THUS THE WAVEFORM WILL TAKE FFH AT ITS POSITIVE PEAK(AT 90O)AND 01H(80H – 7FH) AT ITS NEGATIVE PEAK(AT 270O). PUTTING THE VALUES IN ABOVE EQUATION, Vθ = 7FH SINθ + 80H IF WE CALUCLATE SAMPLES WITH 5O INTERVALS Vθ WILL TAKE VALUES AS FOLLOWS :
8000 8001 8002 8003 8004 8005 8006 8007 8008 8009 800A 800B 800C 800D 800E
MVI A 80 OUT CW LXI H 8500 MVI C 72 MOV A M OUT PA CALL DLY
3E 80 D3 40 21 00 85 0E 72 7E D3 41 CD 00 85
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800F 8010 8011 8012 8013 8014 8015 8016 Θ(DEG) 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
INX H DCR C JNZ 8009 JMP 8004
Vθ 8BH 96H A1H ABH B6H C0H C9H D2H DAH E1H E8H EEH F3H F7H FAH FDH FFH FFH
Θ(DEG) 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180
23 0D C2 09 80 C3 04 80
; ; ; ; ; ; ; ; Vθ FFH FDH FAH F7H F3H EEH E8H E1H DAH D2H C9H C0H B6H ABH A1H 96H 8BH 80H
Θ(DEG) 185 190 195 200 205 210 215 220 225 230 235 240 245 250 255 260 265 270
Vθ 75H 6AH 5FH 55H 1AH 41H 37H 2EH 26H 1FH 18H 12H 0DH 09H 05H 03H 01H 01H
Θ(DEG) 275 280 285 290 295 300 305 310 315 320 325 330 335 340 345 350 355 360
THE SAMPLED VALUES ARE KEPT IN THE MEMORY STARTING FROM 8500 AND CALLED ONE BY ONE TO
Vθ 01H 03H 05H 09H 0DH 12H 18H 1FH 26H 2EH 37H 41H 4AH 55H 5FH 6AH 75H 80H
OBTAIN A SINUSOIDAL WAVEFORM THE FREQUENCY OF SINUSOIDAL WAVEFORM DEPENDS ON THE DELAY CALUCLATION. 8255 – PROGRAMMABLE PERIPHERAL INTERFACE D7
D6
D5
PORT C – PC3 – PC0 1 = INPUT 0 = OUTPUT PORT B – PB7 – PB0 1 = INPUT 0 = OUTPUT MODE 0 – MODE 0 1 – MODE 1
1 – I/O MODE 0 – BSR MODE
PORT C – PC7 – PC4 1 = INPUT 0 = OUTPUT
D4
D3
D2
D1
D0
PORT A – PA7 – PA0 1 – INPUT 0 – OUTPUT MODE 00 – MODE 0 01 – MODE 1 1X – MODE
WE KNOW THAT 8085 MICROPROCESSOR DOES NOT CONTAIN ANY PORTS TO IT TO INTERFACE PERIPHERAL DEVICES HENCE IT REQUIRES AN ADDITIONAL CHIP SO AS TO INTERFACE PERIPHERAL DEVICES FOR THIS TO BE ACHIEVED WE USE A PROGRAMMABLE PERIPERAL INTERFACE 8255 IC. THIS IC CONSISTS OF 3 PORTS NAMELY PORT A, PORT B, PORT C EACH OF WIDTH 8-BIT . HERE IN THIS CHIP TWO PORTS(PORT A AND PORT B) WORK AS 8-BIT PORTS BUT PORT C CAN WORK AS 8-BIT PORT OR AS TWO 4-BIT PORTS. HERE WE CAN CONCLUDE THAT OUR 8255 PROVIDES US THE TOTAL OF 24 LINES (3 PORTS) WHICH CAN BE USED EITHER AS INPUT OR OUTPUT PORTS. BUT TO DEFINE ALL THIS PORTS AND MODES WE REQUIRE A WORD TO DEFINE ALL THIS WHETHER TO SELECT PORTS AS INPUT OR OUTPUT OTHERWISE FOR MODE SELECTION ETC., THIS WORD IS KNOWN AS CONTROL WORD. THE 8085 CAN OPERATE IN THREE MODES OF OPERRATION 1. SIMPLE I/O MODE. 2. STROBED I/O MODE. 3. BIDIRECTIONAL DATA TRANSFER. DURING INTERFACING WE USE SIMPLE I/O MODE FOR INTERFACING DAC’S, ADC’S, LED DISPLAYS ETC., STEPS TO INTERFACE EXTERNAL DEVICES WITH 8255 1. WRITE THE PROPER CONTROL WORD TO CONTROL WORD REGISTER
2. IDENTIFY THE ADDRESSES OF THE PORTS (PORT A, PORT B, PORT C) FROM THE MANUAL. 3. THE ADDRESSES FOR THE PORTS AND CONTROL WORD REGISTER FOR THE KIT WE ARE USING ARE AS FOLLOWS : CONTROL WORD PORT A
-
PORT B
-
PORT C
-
BY USING THIS ADDRESSES WE CAN EITHER ACCEPT DATA AS INPUT OR WE CAN SEND DATA OUTPUT TO CONTROL THE DEVICE. THE LAST STEP IS TO PREPARE THE ALGORITHM AND WRITE THE PROGRAM AS PER THE REQUIREMENT.
INTERFACING ADC TO 8085
TO INTERFACE ADC TO MICROPROCESSOR WE REQUIRE TO FOLLOW THE FOLLOWING STEPS: The analog part of the circuit consists of a high input impedance buffer a1, precision integrator a2 and a voltage comparator.
The converter first integrates the analog input signal va for a fixed duration of 2n clock periods.
Then it integrates an internal reference voltage vr of opposite polarity until the integrator output is zero.
The number n of clock cycles required to return the integrator to zero is proportional to the value of va averaged over the integration period.
Hence, n represents the desired output code. The operation of the circuit is as follows :
Before the start command arrives, the switch sw1 is connected to ground and sw2 is closed. Any offset voltage present in the a1, a2, comparator loop after integration, appears across the capacitor caz till the threshold of the comparator is achieved.
The capacitor caz thus provides automatic compensation for the input offset voltage of all the three amplifiers.
When sw2 opens, caz acts as a memory to hold the voltage required to keep the offset nulled.
At the arrival of start command at t=t1 , the control logic opens sw2 and connects sw1 to va and enables the counter starting from zero.
The circuit uses an n-stage ripple counter and therefore the counter resets to zero after counting 2n pulses.
The analog voltage va is integrated for a fixed number 2n counts of clock pulses after which the counter resets to zero.
If the clock period is t, the integration takes place for a time t1 = 2n x t and the output is ramp going downwards as in fig 2.
The counter resets itself to zero at the end of the interval t1 and the switch sw1 is connected to the reference voltage (-vr). The output voltage vo will now have a positive slope. As long as vo is negative , the output of the comparator is positive and control logic allows the clock pulse to be counted. However, when vo becomes just zero at time t=t3, the control
logic issues an end of conversion(eoc) command and no further clock pulses enter the counter.
It can be shown that the reading of the counter at t s is proportional to the analog input voltage va In fig 2, t1 = t2 – t1 = (2n counts / clock rate) And t3 – t2 = (digital count n / clock rate) For an integrator, δv0 = (-1/rc)v(δt)
The voltage vo will be equal to v1 at the instant t2 and can be written as v1 = (-1/rc ) va(t2 – t1) So,
va (t2 – t1) = vr (t3 –t2)
Putting, the values of (t2 – t1) = 2n and (t3 – t2) = n, we get, va = (vr) (n/2n). The main disadvantage of the dual slope ADC is long conversion time.
Program to Interface ADC to 8085 Microprocessor : 8000 MVI A 82
3E ;
8001 8002 8003 8004 8005 8006 8007 8008 8009 800A 800B 800C 800D 800E 800F 8010 8011 8012 8013 8014 8015 8016 8017 8018 8019 801A 801B 801C 801D 801E 801F 8020 8021 8022 8023
OUT 43 MVI A 02 OUT 40 NOP NOP NOP NOP NOP NOP MVI A 01 OUT 40 LXI H 02C0 DCX MOV ORA JNZ
H A H L 8015
MVI A 04 OUT 40 MVI B 00 INR B IN 41
82 D3 43 3E 02 D3 40 00 00 00 00 00 00 3E 01 D3 40 21 C0 02 2B 7C B5 C2 15 80 3E 04 D3 40 06 00 04 DB 41
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8024 8025 8026 8027 8028 8029 802A 802B 802C 802D 802E 802F 8030 8031
Integrator o/p voltage Vo
ANI 01 JNZ 8021 MVI A 02 OUT 40 MOV A B STA 8501 HLT
E6 01 C2 21 80 3E 02 D3 40 78 32 01 85 76
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AUTOZER t1
T1 = 2n T
N-Cycles t3
t2
Time T
V1 Integrate Va
Integrate (-VR)
Fig :- 2 :- integrated o/p waveform of dual slope ADC
START
Control
N– STAGE
d 0
d
EOC
Fig : 1 Functional diagram of a dual slope ADC
INTERFACING STEPPER MOTOR TO 8085 : MOTOR ELECTRICAL BASICS A step motor is a constant output power transducer, where power is defined as torque multiplied by speed. This means motor torque is the inverse of motor speed. To help understand why a step motor’s power is independent of speed, we need to construct (figuratively) an ideal step motor. An ideal step motor would have zero mechanical friction, its torque would be proportional to ampere-turns and its only electrical characteristic would be inductance. Ampere-turns simply mean that torque is proportional to the number of turns of wire in the motor’s stator multiplied by the current passing through those turns of wire. Anytime there are turns of wire surrounding a magnetic material such as the iron in the motor’s stator, it will have an electrical property called inductance. Inductance describes the energy stored in a magnetic field anytime current passes through this coil of wire. Inductance (L) has a property called inductive reactance, which for the purposes of this discussion may be thought of as a resistance proportional to frequency and therefore motor speed. According to ohm’s law, current is equal to voltage divided by resistance. In this case we substitute inductive reactance for resistance in ohm’s law and conclude motor current is the inverse of motor speed.
Since torque is proportional to ampere-turns (current times the number of turns of wire in the winding), and current is the inverse of speed, torque also has to be the inverse of speed. In an ideal step motor, as speed approaches zero, its torque would approach infinity while at infinite speed torque would be zero. Because current is proportional to torque, motor current would be infinite at zero speed as well. Electrically, a real motor differs from an ideal one primarily by having a non-zero winding resistance. Also the iron in the motor is subject to magnetic saturation, as well as having eddy current and hysteresis losses. Magnetic saturation sets a limit on current to torque proportionality while eddy current and hysteresis (iron losses) along with winding resistance (copper losses) cause motor heating.
Motors convert electrical energy into mechanical energy. A stepper motor converts electrical pulses into specific rotational movements. The movement created by each pulse is precise and repeatable, which is why stepper motors are so effective for positioning applications. Permanent Magnet stepper motors incorporate a permanent magnet rotor, coil windings and magnetically conductive stators. Energizing a coil winding creates an electromagnetic field with a north and south pole as shown in figure 1. The stator carries the magnetic field which causes the rotor to align itself with the magnetic field. The magnetic field can be altered by sequentially energizing or “stepping” the stator coils which generates rotary motion.
Figure 2 illustrates a typical step sequence for a two phase motor. In Step 1 phase A of a two phase stator is energized. This magnetically locks the rotor in the position shown, since unlike poles attract. When phase A is turned off and phase B is turned on, the rotor rotates 90clockwise. In Step 3, phase B is turned off and phase A is turned on but with the polarity reversed from Step 1. This causes another 90rotation. In Step 4, phase A is turned off and phase B is turned on, with polarity reversed from Step 2. Repeating this sequence causes the rotor to rotate clockwise in 90steps. The stepping sequence illustrated in figure 2 is called “one phase on” stepping. A more common method of stepping is “two phase on” where both phases of the motor are always energized. However, only the polarity of one phase is switched at a time, as shown in figure 3. With two phase on stepping the rotor aligns itself between the “average” north and “average” south magnetic poles. Since both phases are always on, this method gives 41.4% more torque than “one phase on” stepping, but with twice the power input.
Half Stepping The motor can also be “half stepped” by inserting an off state between transitioning phases. This cuts a stepper’s full step angle in half. For example, a
90stepping motor would move 45on each half step, figure 4. However, half stepping typically results in a 15% - 30% loss of torque depending on step rate when compared to the two phase on stepping sequence. Since one of the windings is not energized during each alternating half step there is less electromagnetic force exerted on the rotor resulting in a net loss of torque.
Bipolar Winding The two phase stepping sequence described utilizes a “bipolar coil winding.” Each phase consists of a single winding. By reversing the current in the windings, electromagnetic polarity is reversed. The output stage of a typical two phase bipolar drive is further illustrated in the electrical
schematic diagram and stepping sequence in figure 5. As illustrated, switching simply reverses the current flow through the winding thereby changing the polarity of that phase.
Unipolar Winding Another common winding is the unipolar winding. This consists of two windings on a pole connected in such a way that when one winding is energized a magnetic north pole is created, when the other winding is energized a south pole is created. This is referred to as a unipolar winding because the electrical polarity, i.e. current flow, from the drive to the coils is never reversed. The stepping sequence is illustrated in figure 6. This design allows for a simpler electronic drive. However, there is approximately 30% less torque available compared to a bipolar winding. Torque is lower because the energized coil only utilizes half as much copper as compared to a bipolar coil.
Accuracy
The accuracy for can-stack style steppers is 6 - 7% per step, noncumulative. A 7.5stepper will be within 0.5of theoretical position for every step, regardless of how many steps are taken. The incremental errors are noncumulative because the mechanical design of the motor dictates a 360movement for each full revolution. The physical position of the pole plates and magnetic pattern of the rotor result in a repeatable pattern through every 360rotation (under no load conditions).
Resonance
Stepper motors have a natural resonant frequency as a result of the motor being a spring-mass system. When the step rate equals the motor’s natural frequency, there may be an audible change in noise made by the motor, as well as an
increase in vibration. The resonant point will vary with the application and load, but typically occurs somewhere between 70 and 120 steps per second. In severe cases the motor may lose steps at the resonant frequency. Changing the step rate is the simplest means of avoiding many problems related to resonance in a system. Also, half stepping or micro stepping usually reduces resonance problems. When accelerating to speed, the resonance zone should be passed through as quickly as possible.
Torque The torque produced by a specific rotary stepper motor is a function of: • The step rate • The current through the windings • The type of drive used (The force generated by a linear motor is also dependent upon these factors.) Torque is the sum of the friction torque (Tf) and inertial torque (Ti). T= Tf + Ti The frictional torque (ounce-inches or gram-cm) is the force (F), in ounces or grams, required to move a load multiplied by the length, in inches or cm, of the lever arm used to drive the load (r) as shown in figure 8.
Tf = F • r
Figure 8. Frictional torque is the force (F) required to move a load multiplied by the length of the lever arm (r).
The inertial torque (Ti) is the torque required to accelerate the load (gram-cm2).
It should be noted that as the step rate of a motor is increased, the back electromotive force (EMF) (i.e. the generated voltage) of the motor also increases. This restricts current flow and results in a decrease in useable output torque.
AC Synchronous Motors
Stepping motors can also be run on AC (Alternating Current). However, one phase must be energized through a properly selected capacitor. In this case the motor is limited to only one synchronous speed. For instance, if 60 hertz is being supplied, there are 120 reversals or alterations of the power source. The phase being energized by a capacitor is also producing the same number of alterations at an offset time sequence. The motor is really being energized at the
equivalent of 240 steps per second. For a 15rotary motor, 24 steps are required to make one revolution (24 SPR). This becomes a 600 RPM synchronous motor.
In the case of a linear actuator the linear speed produced is dependent on the resolution per step of the motor. For example if 60 hertz is supplied to a .001”/ step motor the resulting speed is .240” per second (240 steps per second times .001”/step). Many of HSI’s stepping motors are available as 300 or 600 RPM AC synchronous motors.
Drives Stepper motors require some external electrical components in order to run. These components typically include a power supply, logic sequencer, switching components and a clock pulse source to determine the step rate. Many commercially available drives have integrated these components into a complete package. Some basic drive units have only the final power stage without the controller electronics to generate the proper step sequencing.
Bipolar Drive
This is a very popular drive for a two phase bipolar motor having four leads. In a complete driver/controller the electronics alternately reverse the current in each phase. The stepping sequence is shown in figure 5.
Unipolar Drive
This drive requires a motor with a center-tap at each phase (6 leads). Instead of reversing the current in each phase, the drive only has to switch current from one coil to the other in each phase (figure 6). The windings are such that this switching reverses the magnetic fields within the motor. This option makes for a simpler drive but only half of the copper winding is used at any one time. This results in approximately 30% less available torque in a rotary motor or force in alinear actuator as compared to an equivalent bipolar motor.
L/R Drives This type of drive is also referred to as a constant voltage drive. Many of these drives can be configured to run bipolar or unipolar stepper motors. L/R stands for the electrical relationship of inductance (L) to resistance (R). Motor coil impedance vs. step rate is determined by these parameters. The L/R drive should “match” the power supply output voltage to the motor coil voltage rating for continuous duty operation. Most published motor performance curves are based on full rated voltage applied at the motor leads. Power supply output voltage level must be set high enough to account for electrical drops within the drive circuitry for optimum continuous operation. Performance levels of most steppers can be improved by increasing the applied voltage for shortened duty cycles. This is typically referred to as “over-driving” the motor. When over-driving a motor, the operating cycle must have sufficient periodic off time (no power applied) to prevent the motor temperature rise from exceeding the published specification.
Chopper Drives
A chopper drive allows a stepper motor to maintain greater torque or force
at higher speeds than with an L/R drive. The chopper drive is a constant current drive and is almost always the bipolar type. The chopper gets its name from the technique of rapidly turning the output power on and off (chopping) to control motor current. For this setup, low impedance motor coils and the maximum voltage power supply that can be used with the drive will deliver the best performance. As a general rule, to achieve optimum performance, the recommended ratio between power supply and rated motor voltage is eight to one. An eight to one ratio was used for the performance curves in this catalog.
Microstepping Drives Many bipolar drives offer a feature called microstepping. Microstepping electronically divides a full step into smaller steps. For instance, if one step of a linear actuator is 0.001 inch, this can be driven to have 10 microsteps per step. In this case, one microstep would normally be 0.0001 inch. Microstepping effectively reduces the step increment of a motor. However, the accuracy of each microstep has a larger percentage of error as compared to the accuracy of a full step. As with full steps, the incremental errors of microsteps are noncumulative.
Fatigue / Life
With proper application, HSI’s linear actuators deliver up to 20 million cycles and HSI’s rotary motors provide up to 25,000 hours of service. Ultimately motor fatigue and resultant life are determined by each customer’s unique application. The following definitions are important for understanding motor life and fatigue.
Continuous Duty: Running a motor at its rated voltage. 25% Duty Cycle: Running a motor at double its rated voltage on an L/R drive. The motor is “on” approximately 25% of the time. The motor generates about 60% more output than at rated voltage. Note, duty cycle is not related to the load placed on the motor. Life: A linear actuator’s life is the number of cycles that the motor is able to move at a prescribed load and maintain step accuracy. Rotary motor life is the number of hours of operation. One Cycle: A linear actuator’s cycle consists of extending and retracting back to the original position.
Terminology :
Detent or residual torque: The torque required to rotate the motor’s output shaft with no current applied to the windings. Drives: A term depicting the external electrical components to run a Stepper Motor System. This will include power supplies, logic sequencers, switching components and usually a variable frequency pulse source to determine the step rate. Dynamic torque: The torque generated by the motor at a given step rate. Dynamic torque can be represented by PULL IN torque or PULL OUT torque.
Holding torque: The torque required to rotate the motor’s output shaft while the windings are energized with a steady state D.C. current. Inertia: The measure of a body’s resistance to acceleration or deceleration. Typically used in reference to the inertia of the load to be moved by a motor or the inertia of a motor’s rotor. Linear step increment: The linear travel movement generated by the leadscrew with each single step of the rotor. Maximum temperature rise: Determined by the resistance rise method, motor unmounted in free air and energized with a steady state D.C. current. Pull in torque: The load a motor can move without missing steps when started at a constant pulse rate. Pull out torque: The load a motor can move when at operating speed. This is normally substantially greater than the Pull in torque. Pulse rate: The number of pulses per second (pps) applied to the windings of the motor. The pulse rate is equivalent to the motor step rate. Pulses per second (PPS): The number of steps that the motor takes in one second (sometimes called “steps per second”). This is determined by the frequency of pulses produced by the motor drive.
Ramping: A drive technique to accelerate a given load from a low step rate, to a given maximum step rate and then to decelerate to the initial step rate without the loss of steps. Single step response: The time required for the motor to make one complete step. Step: The angular rotation produced by the rotor each time the motor receives a pulse. For linear actuators a step translates to a specific linear distance. Step angle: The rotation of the rotor caused by each step, measured in degrees. Steps per revolution: The total number of steps required for the rotor to rotate 360. Torque to inertia ratio: Holding torque divided by rotor inertia.
0000 0001 0002 0003 0004 0005 0006 0007 0008 0009 000A 000B 000C 000D 000E
MVI A 80
8050 8051 8052 8053 8054 8055 8056 8057 8058 8059 805A 805B 805C 805D 805E 805F 8060 8061
PUSH PSW LXI H 0001
OUT 43 MVI A 88 OUT 40 CALL8050 RLC JMP 0006
LXI D 0FFF DCX MOV ORA JNZ
D A D E 8057
DCX MOV ORA JNZ
H A H L 8054
3E 80 D3 43 3E 88 D3 40 CD 50 80 07 C3 06 00
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F5 21 01 00 11 FF 0F 1B 7A B3 C2 57 80 2B 7C B5 C2 54
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8062 8063 POP 8064 RET
PSW
80 ; F1 ; C9 ;
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