Place three shunts two pin jumpers vertically on j3

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Unformatted text preview: ble Technical Documents 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 for Full-Bridge”. Place three shunts (two pin jumpers) vertically on J3 where it is labeled “Connect for Full-Bridge”. 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. VDD POT1 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 Winding 2 R Y Stepper Winding 1 Br 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 Instructions 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 application. Objectives 1. Use the provided PIC® MCU Communicator GUI to manipulate the I/O on the PIC16F917. 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 VDD U18 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 3 4 C21 0.1 μF PIC16F917 11/32 VDD 5 C20 0.1 μF R60 11 25 14 TX 10 300 Ω 7 12 13 8 9 0.1 μF 6 V- GND 15 R61 26 RX MAX3232CUE...
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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.

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