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Stepping Motor Fundamentals Application Note, AN907 (DS00907)
Stepper Motor Control Using the PIC16F684 Application Note, AN906 (DS00906) Jumper Configuration
• AN0 (J13) to POT1 (J4)
RA4 (J13) to SW2 (J4)
RD7 (J10) to P1 (J1)
RD6 (J10) to P2 (J1)
RD5 (J10) to P3 (J1)
RD4 (J10) to P4 (J1)
CCP1 (J10) to PWM1 (J1)
CCP2 (J10) to PWM3 (J1)
Place three shunts (two pin jumpers) vertically on J2 where it is labeled “Connect
Place three shunts (two pin jumpers) vertically on J3 where it is labeled “Connect
Connect the BROWN lead of the stepper motor to Drive 1 (P9).
Connect the ORANGE lead of the stepper motor to Drive 2 (P10).
Connect the RED lead of the stepper motor to Drive 3 (P12).
Connect the YELLOW lead of the stepper motor to Drive 4 (P11).
Connect the right and center pins of JP8 using a shunt. © 2005 Microchip Technology Inc. DS51557B-page 35 PICDEMTM Mechatronics Demo Board User’s Guide DS51557B-page 36 Yellow Red Orange PROJECT 7: JUMPER DIAGRAM Brown FIGURE 2-14: © 2005 Microchip Technology Inc. © 2005 Microchip Technology Inc.
10 kΩ SW2 12/31 C26
1000 pF VSS 7 AN0 3 RA1 VDD CCP2 24 * RD4 27 * RD5 28 CCP1 21 * RD6 29 5 kΩ * 5 kΩ 5 kΩ VDD 5 kΩ * 5 kΩ VDD 5 kΩ * * * * = These are simplified circuits that show the equivalent functionality. 1 kΩ R10 1 kΩ R5 11/32 * * VDD Stepper
Or VDD VDD * * * * FIGURE 2-15: R4
10 kΩ VDD VDD RD7 30 PIC16F917 VDD Example Projects PROJECT 7: SCHEMATIC DS51557B-page 37 PICDEMTM Mechatronics Demo Board User’s Guide
Adjusting POT1 varies the speed of the motor. Toggle between single stepping, half
stepping, and microstepping modes by pressing SW2. At low speeds, the motor should
noticeably step in single stepping and half stepping modes. The movement will be quite
jerky in both modes, though to a lesser extent in the half stepping mode. In
microstepping mode, the jerky motion should be virtually eliminated. Discussion
Stepper motors are used in many positioning applications. For example, ink jet printers
and smaller CNC machines employ stepper motors. Stepper motors are ideal for these
applications because, as long as they are not overloaded, the distance a stepper motor
moves is always known. Stepper motors are also brushless, which makes them more
reliable than brushed motors. Finally, stepper motors are very responsive to starting
and stopping and will produce the highest torque at low speeds.
Half stepping is used to give a stepping motor two times its rated step resolution.
However, there is a word of caution. A stepper motor is typically not rated to have more
than one winding energized at a time. As a result, the motor will heat up if both windings
are energized at the rated voltage of the motor. To offset this, when both windings are
energized simultaneously, the average current to each winding should be 0.707 times
the rated current.
Microstepping offers several advantages over single stepping and half stepping. First,
torque is fairly constant between steps. This results in smoother rotation and decreased
shaft oscillation. Secondly, a higher step resolution is achieved. This means a low-cost
motor can be used in an application that would normally require a more expensive,
higher resolution motor. Finally, the current in the motor windings is being controlled in
a way that prevents the motor from running outside its rated current, thereby eliminating
the excess heat associated with half stepping. The drawback to microstepping is that
the drive circuitry is more complex. DS51557B-page 38 © 2005 Microchip Technology Inc. Example Projects
2.3.8 Project 8: PC Interface Using the USART Communicating with the serial port on a PC is a very useful tool. Applications include
a piece of test equipment that needs to interface to a PC or a design that uses the serial
port during development to configure the device. In this project, the PIC16F917 will use
the USART to receive commands from a PC application. Another notable feature to this
project is that the firmware implements an auto-baud routine to sync up with the
1. Use the provided PIC® MCU Communicator GUI to manipulate the I/O on the
2. Understand what an auto-baud routine entails. Applicable Technical Documents
Asynchronous Communications with the PICmicro® USART Application Note, AN774
(DS00774) Jumper Configuration
• Make sure there are no jumpers or shunts on JP2.
• RD7 (J10) to D0 (J14)
• Connect a serial cable between the board and PC
FIGURE 2-16: © 2005 Microchip Technology Inc. PROJECT 8: JUMPER DIAGRAM DS51557B-page 39 PICDEMTM Mechatronics Demo Board User’s Guide
FIGURE 2-17: PROJECT 8: SCHEMATIC
C17 0.1 μF 16 VCC
C17 0.1 μF 2
J19 1 6 2 7 3 8 4 9 5 DE9S-FRS C17 V+ 1
4 C21 0.1 μF PIC16F917
11/32 VDD 5 C20 0.1 μF
0.1 μF 6 V- GND 15
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This note was uploaded on 01/29/2014 for the course AA AA taught by Professor Aa during the Winter '10 term at ENS Cachan.
- Winter '10