ECE 4510/5530 Microcontroller Applications Week 13

Transcription

1 ECE 4510/5530 Microctroller Applicatis Week 13 Dr. Bradley J. Bazuin Associate Professor Department of Electrical and Computer Engineering College of Engineering and Applied ciences

2 General Informati More Motors tepper Motors ECE

3 tepper Motor Ctrol (Chap. 7) It is digital in nature and provides high degree of ctrol. A DC motor is typically used for ctinuous turning and is driven to maintain a desired velocity A tepper Motor is typically used for positiing and has a precise drive sequence that provides defined angular steps Example 3.6 degrees per step so that 360 degrees is 100 steps. In its simplest form, a stepper motor has a permanent magnet rotor and a stator csisting of two coils. The rotor aligns with the stator coil that is energized. By changing the coil that is energized, the rotor is turned. Figure 7.45a to 7.45d illustrate how the rotor rotates clockwise in full step. By changing the energizing order as shown in Figure 7.46, the stepper will rotate counterclockwise in full step.

4 tepper Motor Ctrol Two Drive, 4 Coils current flow C4 C4 1st 1st C2 C1 C2 C1 C3 current flow C3 2nd 2nd Figure 7.45a tepper motor full step 1 Figure 7.45b tepper motor full step 2 A course stepper motor with steps of 45 degrees.

5 tepper Motor Ctrol Four Drives, 8 Coils C7 C8 C1 C2 C3 rotor By increasing the number of coils and magnet arms the rotor, smaller angular steps can be achieved. C6 C4 C5 Figure 7.48 Actual internal cstructi of step motor

6 tepper Motor Drivers V CC V CC Q4 The UL2803 can provide current sinking PP3 PP2 Q3 tep Motor PP1 V CC V CC PP0 Q2 V CC V CC Q1 Figure 7.49 Driving a step motor

7 tepper Motor Wikipedia Waveforms The Java app the top of the page demstrate the wave drive sequence. ECE 4510/5530 7

8 tepper Motor Drivers Table 7.17 Full-step sequence for clockwise rotati tep Q1 PP0 Q2 PP1 Q3 PP2 Q4 PP3 value Table 7.18 Half-step sequence for clockwise rotati tep Q1 PP0 Q2 PP1 Q3 PP2 Q4 PP3 value

9 Generating equences imple Generating a Full tep equence It appears to be a shift sequence What happens if you shift right or left. The stepper would follow You must perform a circular or end-around shift 0001 > 1 results in 0000, so or in 1000 Would this be easier to program if it were an 8-bit char? ? ECE 4510/5530 9

10 Generating equences Complex Use the step number as a circular counter Then decode the output pins desired This will work for both complex and simple sequences ECE 4510/

11 Optical otary haft Encoder Optical shaft encoder with pushbutt ECE 4510/5530 Digikey $ D 11

12 Optical otary haft Encoder ECE 4510/5530 Detect turn directi by which rising edge leads. 16 or 32 positi degree or 22.5 degree for code change imilar device used unseeker to engage and ctrol cruise ctrol 12

13 unseeker haft Tracking Code // Keep track of encoders enc1_new = (P1I & (EC1_B EC1_A)); switch(enc1_old){ case TATE_1_A: // 00 if( enc1_new == TATE_1_B ){ encoder1--; cruise_velocity -= CUIE_TEP; else if( enc1_new == TATE_1_D ){ encoder1++; cruise_velocity += CUIE_TEP; break; case TATE_1_B: // 01 if( enc1_new == TATE_1_C ){ encoder1--; cruise_velocity -= CUIE_TEP; else if( enc1_new == TATE_1_A ){ encoder1++; cruise_velocity += CUIE_TEP; ECE 4510/5530 break; case TATE_1_C: // 11 if( enc1_new == TATE_1_D ){ encoder1--; cruise_velocity -= CUIE_TEP; else if( enc1_new == TATE_1_B ){ encoder1++; cruise_velocity += CUIE_TEP; break; case TATE_1_D: // 10 if( enc1_new == TATE_1_A ){ encoder1--; cruise_velocity -= CUIE_TEP; else if( enc1_new == TATE_1_C ){ encoder1++; cruise_velocity += CUIE_TEP; break; default: break; 13 enc1_old = enc1_new;

14 Wireless Communicatis The XBee/XBee-PO DigiMesh 2.4 F Modules were engineered to support the unique needs of low-cost, low-power wireless sensor networks. The modules require minimal power and provide reliable delivery of data between remote devices. The modules operate within the IM 2.4 MHz frequency band. XBee-PO Indoor/Urban: up to 300 ft (100 m) Outdoor line-of-sight: up to 1 mile (1500 m) Transmit Power Output: 100 mw (20 dbm) EIP eceiver ensitivity: -100 dbm F Data ate: 250 kbps Embedded interface: UAT with x and Tx ECE 4510/