EDE1204 Bi-Polar Stepper Motor IC
EDE1204
Coil B Control Signal
Coil B Control Signal
Connect to +5V DC
Connect to +5V DC
Digital Ground
0 = Disable Motor Drivers
1 = Clockwise, 0 = Counter-Clockwise
1 = Normal Stepping, 0 = Half-Stepping
1
2
3
4
5
6
7
8
Coil B
Coil B
+5V
+5V
GND
Free Spin
Direction
Half-Stepping
Step
Coil A
Coil A
OSC1
OSC2
+5V
C
B
A
Run
18
17
16
15
14
13
12
11
10
Coil A Control Signal
Coil A Control Signal
Oscillator Connection
Oscillator Connection
Connect to +5V DC
Speed Control (MSB)
Speed Control
Speed Control (LSB)
1 = 'STEP' mode, 0 = 'RUN' mode
Single-Step on Falling Edge in 'STEP' mode
9
The EDE1204 Bi-Polar Stepper Motor IC is a 5 volt, 18 pin package designed to control a Bi-Polar (4
wire) stepper motor. The EDE1204 is capable of self-clocking in the free-standing 'RUN' mode, as
well as external clocking in the 'STEP' mode. In addition, half-stepping and directional control are
also available. The TTL-level outputs sequence dual H-Bridges (one per coil) such as the L293 Dual
H-Bridge IC or dual H-Bridges made from discrete transistors (see schematics section). The
EDE1204 features the ability to change the stepping rate while the motor is stepping and to self-
clock an unlimited number of steps in continuous 'RUN' mode. Inputs are TTL/ CMOS compatible.
RUN mode
In the 'RUN' mode, activated by a low on pin 10, the EDE1204 will cause the motor to rotate
according to the following parameters:
Direction
(pin 7): 1 = clockwise, 0 = counter-clockwise
(If a clockwise command causes counterclockwise rotation of motor, reverse the
sequence of the motor’s four phase wires.)
Half-Stepping
(pin 8): 1 = normal stepping, 0 = half stepping (doubles step resolution)
Speed Control
[C,B,A] (pins 13,12,11): these three active-low bits select one of eight
rotational speeds. Refer to Tables One & Two below for speed range details.
Note: Throughout this datasheet, "1" refers to +5V, and "0" refers to 0V (Ground).
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©
1998
E-LAB Digital Engineering, Inc. All rights reserved. Page 1
Revolutions per second & minute are based upon a 1.8 º per step motor.
EDE1204 external clock speed is 4 MHz.
Speed Input (C,B,A)
RPS
RPM
Table One - Full Step 'RUN' mode speeds*:
000
001
010
011
100
101
110
111
.152
.172
.2
.244
.303
.4
.606
1.18
9.1
10.3
12
14.6
18.2
24
36.4
70.6
Revolutions per second & minute are based upon a 1.8 º per step motor.
EDE1204 external clock speed is 4 MHz.
Speed Input (C,B,A)
RPS
RPM
Table Two - Half-Step 'RUN' mode speeds*:
000
001
010
011
100
101
110
111
.077
.089
.103
.121
.154
.2
.303
.606
4.6
5.3
6.2
7.27
9.2
12
18.2
36.4
* Note: indicated speeds are approximate and may vary with oscillator frequency and other factors.
Please verify exact value before using in any speed-critical application.
The following chart depicts revolutions per second for a 1.8 º stepper motor, in relation to the three
speed selection bits, for both full and half stepping. Please note that the speed increase is
nonlinear; i.e. finer speed control is available at slower step speeds. Again, indicated speeds are
approximate and will vary with oscillator frequency. Please verify exact value before using in any
speed-critical application.
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1998
E-LAB Digital Engineering, Inc. All rights reserved. Page 2
Motor Speed vs. Speed Selection Bits
1.2
1
0.8
RPS, Full
RPS, Half
0.606
0.606
0.4
0.2
1.18
RPS
0.6
0.4
0.2
0
0
0.152
0.077
1
0.244
0.121
3
4
0.303
0.154
5
0.303
0.172
0.089
2
0.2
0.103
6
7
Speed Select Input
STEP mode
In the 'STEP' mode, an external clock signal is required for each step of the motor. The RUN (pin
10) line must be left high. Each low-going pulse on the STEP (pin 9) line causes a movement of the
motor according to the Direction and Half-step pins as specified below:
Direction
(pin 7): 1 = clockwise, 0 = counter-clockwise
(If a clockwise command causes counterclockwise rotation of motor, reverse the
sequence of the motor’s four phase wires.)
Half-Stepping
(pin 8): 1 = normal stepping, 0 = half stepping (doubles step resolution)
With the EDE1204 running at an external clock speed of 4 MHz, the 'STEP' pin may be driven at
speeds up to 5 KHz, resulting in a motor speed over 1,500 RPM with a 1.8 per step motor . All
º
stepper motors require ramped acceleration to such high RPM rates; do not instantly apply high
speed step requests immediately to a stopped motor. Motor type and load will determine
maximum acceleration rate. However, ordinary speed ranges (such as the EDE1204’s ‘RUN’ mode
speeds) do not require a ramped acceleration.
Free-Spin
Holding the free-spin input (pin 6) low causes the EDE1204 to de-activate both motor coils by
placing each wire of a coil at the same voltage. During ordinary operation (step and run modes) the
motor is held in position by the ‘braking’ effect inherent in all stepper motors. Activating this
active-low input allows the motor spindle to spin freely without the braking effect. Braking effect is
resumed when free-spin input (pin 6) is raised.
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©
1998
E-LAB Digital Engineering, Inc. All rights reserved. Page 3
Hookup Examples
Warning: As activating both sides of an H-Bridge circuit may cause short-circuit current flow, it is
imperative that the two EDE1204 pins labeled 'Coil A' be connected as inputs to one H-Bridge,
and the two EDE1204 pins labeled 'Coil B' be connected as inputs to the other H-Bridge.
Connection via L293 H-Bridge IC (full EDE1204 schematic not shown)
In this first example, The EDE1204 is paired with a L293 Dual H-Bridge IC. The L293 can supply
up to 1A per coil. A variant of the L293, the L293D, includes the output clamping diodes within
the IC. This arrangement is ideal for many applications as it provides a two IC drive circuit.
Pinout for the L293 IC is as follows:
Pin 1: Chip Inhibit
Pin 2: Input 1
Pin 3: Output 1
Pin 4: GND
Pin 5: GND
Pin 6: Output 2
Pin 7: Input 2
Pin 8: Vc (Collector Supply Voltage)
Pin 9: Chip Inhibit 2
Pin 10: Input 3
Pin 11: Output 3
Pin 12: GND
Pin 13: GND
Pin 14: Output 4
Pin 15: Input 4
Pin 16: Vss (Logic Supply Voltage, +5V)
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©
1998
E-LAB Digital Engineering, Inc. All rights reserved. Page 4
Connection via Eight-NPN Transistor H-Bridge (full EDE1204 schematic not shown)
The above circuit utilizes eight NPN transistors. For low-current applications, inexpensive 2N2222
NPN transistors may be used. For higher currents, higher-capacity transistors may be used. One
suitable choice would be ZETEX ZTX690B (high-gain NPN), capable of up to 2A continuous
current.
(ZETEX Semiconductor's web site is
www.zetex.com
)
If a typical, low-gain power
transistor is used, such as the MJE3055T, you may need to modify resistor values due to these
transistors' lower current gain. Notice that the four diodes connecting the emitters to the collectors
must be capable of carrying the motor coil current, and that the eight clamping diodes must be fast
enough for the maximum motor speed to be used. In most instances, a 1N4007 or 1N5408 works
well for the four emitter-collector diodes, and a 1N4007 works well for the eight clamping diodes.
One advantage of using all NPN transistors for the drive circuitry is that it lowers the possibility of
confusion during board assembly & production. Also, using only eight transistors, it results in a
lower production cost than most typical H-Bridge circuits.
COPYRIGHT
©
1998
E-LAB Digital Engineering, Inc. All rights reserved. Page 5
Special Edition for Assessment Centres
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