The Microcontroller Idea Book - Jan Axelson's Lakeview Research

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Chapter 11 Listing 11-3. Controls a stepper motor. 10 REM A=address of output port 20 A=0E400H 30 DO 40 INPUT “Speed (1-15)? ”,S 50 INPUT “Mode (1=wave, 2=2-phase, 3=1/2-step, 4=stop)?”,M 60 INPUT “Direction (0=Clockwise, 1=Counterclockwise)? ”,D 70 IF M=1 THEN X=4 80 IF M=2 THEN X=0 90 IF M=3 THEN X=2 100 IF M=4 THEN X=6 110 XBY(A)=S+(X+D)*10H 120 WHILE 1=1 130 END powering one and two phases. Wave drive uses the least power, but with reduced torque compared to 2-phase drive. Half-step drive uses twice as many steps per revolution, and so offers finer control. Bit 4 (pin 12 of U2) sets the direction of rotation. Figure 11-5. Using a UDN2993 to control a DC motor with pulse-width modulation. 194 The Microcontroller Idea Book
Control Circuits Listing 11-4. Controls direction and speed of a DC motor with BASIC-52’s PWM output. 10 PORT1=0FBH 20 T=1 30 INPUT “Direction (0 or 1)? ”,D 40 INPUT “High (on) pulse width (25 to 0FFFFh)? ”,H 50 INPUT “Low (off time) pulse width (25 to 0FFFFh)? ”,L 60 IF D=0 THEN PORT1=PORT1.AND.0FEH ELSE PORT1=PORT1.OR.1 70 PRINT “Press any key to end program” 80 DO 90 PWM H,L,T 100 G=GET 110 UNTIL G0 120 PORT1=PORT1.AND.0FBH 130 END You can stop the motor in any of three ways. You can bring bits 0-3 of the port low to stop the timer. You can bring bit 7 high, which removes power from U4’s outputs. Or, you can bring pins 9 and 10 of U5 high, which continues to apply power to the motor, but ignores the step input. Listing 11-3 prompts you for a motor speed, mode of operation, and direction, and then runs the motor as requested. You can stop the program, and the motor will continue to run, as long as it remains connected to the port and you don’t write anything else to it. Speed Control of a Continuous DC Motor If you prefer ordinary continuous dc motors to steppers, Figure 11-5 shows a circuit that uses BASIC-52’s PWM output to control motor speed. This circuit uses another Allegro chip, the UDN2993B (U1). Pins 1 and 8 of U1 connect to the motor’s power supply, which can range from 10 to 40V. Pins 6 and 7 connect to the motor. Pin 5 is the +5V logic supply, and pins 4, 5, 12, and 13 are additional grounds. At pins 10, 11, 14, and 15, you can connect and control a second motor. Pin 3 of U1 controls motor direction, and connects to bit 0 of Port 1 (P1.0) on the 8052-BASIC. Pin 2 of U1 switches power to the motor, with a logic low shutting the motor off, and a logic high allowing current to flow. This pin connects to Port1, bit 2 (P1.2) of the 8052-BASIC, which is the PWM output. BASIC-52’s PWM expression causes a series of pulses to appear at P1.2, with this syntax: The Microcontroller Idea Book 195
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The Microcontroller Idea Book Circu
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Table of Contents Chapter 1 Microco
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Chapter 11 Control Circuits 185 Swi
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Introduction Introduction This book
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A chapter on assembly-language inte
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Microcontroller Basics 1 Microcontr
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But along with cheap, powerful, and
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makes sense. For simpler designs, a
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Microcontroller Basics Several tech
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Interpreters and compilers are two
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Inside the 8052-BASIC 2 Inside the
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Inside the 8052-BASIC • You can a
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hardware manuals. For programming,
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Inside the 8052-BASIC Figure 2-2 Pi
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Inside the 8052-BASIC Table 2-2. (p
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Inside the 8052-BASIC Code and data
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Powering Up 3 Powering Up This chap
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Powering Up Table 3-1. Parts list f
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Powering Up Figure 3-2. Truth table
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Powering Up Jumper J3 chooses the c
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Powering Up Figure 3-3. This is the
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Powering Up Construction Tips These
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Powering Up Serial Connectors Conne
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You’re now ready to power up the
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Powering Up PRINT XTAL Line Editing
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Powering Up PORT 1 Bit Values: Bit
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Powering Up Listing 3-3. Allows use
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10 CLOCK 1:TIME=0:SEC=0 20 A=0 30 P
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Saving Programs 4 Saving Programs I
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guaranteed for at least ten years.
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Saving Programs Figure 4-3. Circuit
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Jumper J4 is optional. It enables y
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memory on bootup. This is what allo
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This is the recommended algorithm f
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Saving Programs Figure 4-5. Additio
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problems with EPROMs that have a 10
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supply. The chip requires an additi
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Programming 5 Programming When you
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Subroutines have two advantages. Fi
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Programming • Hexadecimal numbers
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Programming It can be hard to find
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Programming Math Operators = + - *
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Programming expression / expression
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Programming DO: [program statements
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Programming LOG(expression) Returns
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Programming PH0.@ Same as PRINT@, b
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Programming RCAP2 Retrieves or assi
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Programming PRINT TAB(2) “hello
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Inputs and Outputs 6 Inputs and Out
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Unassigned space remains in the mem
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U11 is a 74HCT138 3-to-8-line decod
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If you wish, you can wire U14’s i
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Inputs and Outputs Figure 6-4. Outp
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Inputs and Outputs Listing 6-2. Set
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The 82C55 also has CMOS-compatible
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Inputs and Outputs Pin Symbol Input
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Inputs and Outputs An 8255 Interfac
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Inputs and Outputs XBY(0FC03h)=9BH
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To set or clear a different bit, de
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Switches and Keypads 7 Switches and
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Switches and Keypads Figure 7-2. Us
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exact value depending on the switch
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Switches and Keypads Figure 7-4. Tw
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Switches and Keypads Figure 7-6. A
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Switches and Keypads Custom Keypads
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Switches and Keypads • A single c
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Switches and Keypads Listing 7-3. T
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Displays 8 Displays In addition to
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Displays Figure 8-1. LED interfaces
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Displays Figure 8-2. Ways to connec
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Displays Figure 8-4. Four output po
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Displays Figure 8-5. The ICM7218D c
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In Figure 8-5’s circuit, an 82(C)
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Displays Figure 8-7. With the TC721
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Displays Figure 8-8. With a charact
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Table 8-1. LCD modules containing t
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Page 155 and 156: Displays Interfacing Full control o
Page 157 and 158: Displays Listing 8-4 (page 2 0f 2).
Page 159 and 160: Displays Listing 8-5. Displays key
Page 161 and 162: Displays Listing 8-6 (page 2 of 2).
Page 163 and 164: Using Sensors to Detect and Measure
Page 165 and 166: • What power supplies are availab
Page 171 and 172: different ground symbols for the tw
Page 173 and 174: 10 REM use single-ended mode 20 REM
Page 181 and 182: Clocks and Calendars 10 Clocks and
Page 183 and 184: Listing 10-1. Uses BASIC-52’s rea
Page 185 and 186: Clocks and Calendars Figure 10-1. P
Page 187 and 188: Clocks and Calendars Table 10-1. Re
Page 189 and 190: If you want an alarm frequency othe
Page 191 and 192: Clocks and Calendars Listing 10-3 (
Page 193 and 194: Clocks and Calendars Listing 10-3 (
Page 195 and 196: Control Circuits 11 Control Circuit
Page 197 and 198: the LSTTL part, and wire the desire
Page 199 and 200: Control Circuits Listing 11-1. Cont
Page 201 and 202: Control Circuits Listing 11-2. Demo
Page 203: Control Circuits disables the outpu
Page 207 and 208: Control Circuits Listing 11-5. Cont
Page 209 and 210: Wireless Links 12 Wireless Links Wi
Page 211 and 212: Wireless Links Figure 12-2. This in
Page 213 and 214: Wireless Links Because there are th
Page 215 and 216: Wireless Links Figure 12-4. The GP1
Page 217 and 218: through the LEDs. If you prefer an
Page 219 and 220: Wireless Links Figure 12-6. Using a
Page 221 and 222: Wireless Links Figure 12-7. Using a
Page 223 and 224: Wireless Links IREDs emit energy at
Page 225 and 226: In the infrared link, the amount of
Page 227 and 228: Calling Assembly-language Routines
Page 229 and 230: into memory in the 8052-BASIC syste
Page 231 and 232: 2048h in code memory. This is becau
Page 233 and 234: Binary value 1100 0101 Hex equivale
Page 235 and 236: Successful assembly is a good sign,
Page 237 and 238: statement must match the address in
Page 243 and 244: • BASIC-52’s ON EX1 instruction
Page 249 and 250: Running BASIC-52 from External Memo
Page 251 and 252: 14-1 for longer delays between writ
Page 253 and 254: In Figure 3-1, tie pin 31 of U2 (EA
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Related Products 15 Related Product
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Finally, a compiled BASIC program u
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Related Products Figure 15-3. Blue
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Sources Appendix A Sources This App
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Programming and Interfacing the 805
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Sources Product Vendors The followi
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Sources Electronics 123 17921 Rowla
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Sources Micro Future 40944 Cascado
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Sources Siemens Components 2191 Lau
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Programs for Loading Files Appendix
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Programs for Loading Files Listing
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Number Systems Appendix C Number Sy
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Number Systems This table shows the
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Index Index A ADC, 158 - 169 addres
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Index S sample and hold, 169 SBC, 3
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The Microcontroller Idea Book - Jan Axelson's Lakeview Research

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