The Microcontroller Idea Book - Jan Axelson's Lakeview Research

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Chapter 4 Table 4-2. Parts list for Figure 4-5. Semiconductors D2,D3 Q1,Q2 U10 1N270 or similar germanium diode PN2907 or similar PNP general-purpose transistor 75453 dual peripheral OR driver Resistors (1/4-watt, 5% tolerance) R11,R14 R12,R13 R15,R16 4,700-ohm 10,000-ohm 10,000-ohm Capacitors(16WVDC, 20% tolerance) C15 0.1-microfarad ceramic disc Miscellaneous J5-J6 SIP header, 3-terminal, and shorting block When BASIC-52 executes a programming command, PGM EN goes low, pin 3 of U10 goes low, and Q1 switches on. This brings VPP to 12.5 volts. Diode D2 prevents current from flowing into the 5V supply. When programming is finished, PGM EN goes high again, and VPP returns to +4.7V. Resistor R10 limits U10A’s output current, and R11 ensures that pin 3 of U10 pulls up to 12.5V. Capacitor C14 provides power-supply decoupling. If you happen to have an older 21V EPROM, the circuit should also work with a +21V supply in place of +12.5V. FPROG Circuits If you want to use the FPROG commands for faster EPROM programming, additional circuits are required. These are identical to the circuits that switch VPP, except that they instead switch VCC to +6V during programming. With the FPROG circuits shown in Figure 4-5, during normal (non-programming) operation, VCC is actually slightly less than +5V, due to D3’s voltage drop. This should cause no 60 The Microcontroller Idea Book
problems with EPROMs that have a 10 percent power-supply tolerance; in other words, ones that are guaranteed to operate from supplies of 4.5 to 5.5V. You do want to be sure that your main supply is a solid +5V, or even a little higher. The data sheets for some EPROMs specify 5-percent tolerance: the supply must be between 4.75 and 5.25V to guarantee operation within the specifications. In this case, you will be operating near or just below the recommended supply voltage, especially if your main supply is slightly under +5V. When you are not programming the EPROM, you can move J6 to connect pin 28 directly to +5V. But overall, 10-percent-tolerance EPROMs are a better choice for this circuit. If you are using a NVRAM or EEPROM, set J6 to +5V, since VCC must remain at 5V for these devices. Power Supplies for Programming You have several options for creating the programming power supplies of +12.5V and, optionally, +6V. Benchtop Supply For occasional use, if you have a benchtop supply that can supply the needed outputs, you can add terminals to the appropriate connections in your BASIC-52 system, and connect the supply leads to them when needed. Adjustable Regulator Figure 4-6 shows a circuit that regulates a DC supply of 15 to 18V to 12.5V or 6V. For the 15V supply, you can use a benchtop supply, a wall-transformer AC-to-DC adapter, or even two 9-volt transistor batteries connected in series. The supply must have a DC output, but it doesn’t have to be regulated. You’ll need one LM317 and an R1 and R2 for each output voltage, but you can power both LM317’s from the same supply. Typical current requirements for programming an NMOS 2764A are 50 milliamperes at 12.5V and 75 milliamperes at 6V, or 125 milliamperes total. For a CMOS 27C64, it’s 30 milliamperes for each, or 60 milliamperes total. Each regulating circuit uses an LM317 adjustable regulator. You set the output voltage of the LM317 with R1 and R2, using the formula shown. The LM317 creates a constant 1.25V reference across R1. The current through R1 also flows through R2, and the voltage across the pair of resistors is the regulator’s output. Intel’s EPROM data sheets specify this range for the programming voltages: Saving Programs The Microcontroller Idea Book 61
Page 1 and 2:
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
Page 19 and 20: Interpreters and compilers are two
Page 21 and 22: Inside the 8052-BASIC 2 Inside the
Page 23 and 24: Inside the 8052-BASIC • You can a
Page 25 and 26: hardware manuals. For programming,
Page 27 and 28: Inside the 8052-BASIC Figure 2-2 Pi
Page 29 and 30: Inside the 8052-BASIC Table 2-2. (p
Page 31 and 32: Inside the 8052-BASIC Code and data
Page 33 and 34: Powering Up 3 Powering Up This chap
Page 35 and 36: Powering Up Table 3-1. Parts list f
Page 37 and 38: Powering Up Figure 3-2. Truth table
Page 39 and 40: Powering Up Jumper J3 chooses the c
Page 41 and 42: Powering Up Figure 3-3. This is the
Page 43 and 44: Powering Up Construction Tips These
Page 45 and 46: Powering Up Serial Connectors Conne
Page 47 and 48: You’re now ready to power up the
Page 49 and 50: Powering Up PRINT XTAL Line Editing
Page 51 and 52: Powering Up PORT 1 Bit Values: Bit
Page 53 and 54: Powering Up Listing 3-3. Allows use
Page 55 and 56: 10 CLOCK 1:TIME=0:SEC=0 20 A=0 30 P
Page 57 and 58: Saving Programs 4 Saving Programs I
Page 59 and 60: guaranteed for at least ten years.
Page 61 and 62: Saving Programs Figure 4-3. Circuit
Page 63 and 64: Jumper J4 is optional. It enables y
Page 65 and 66: memory on bootup. This is what allo
Page 67 and 68: This is the recommended algorithm f
Page 69: Saving Programs Figure 4-5. Additio
Page 73 and 74: supply. The chip requires an additi
Page 75 and 76: Programming 5 Programming When you
Page 77 and 78: Subroutines have two advantages. Fi
Page 79 and 80: Programming • Hexadecimal numbers
Page 81 and 82: Programming It can be hard to find
Page 83 and 84: Programming Math Operators = + - *
Page 85 and 86: Programming expression / expression
Page 87 and 88: Programming DO: [program statements
Page 89 and 90: Programming LOG(expression) Returns
Page 91 and 92: Programming PH0.@ Same as PRINT@, b
Page 93 and 94: Programming RCAP2 Retrieves or assi
Page 95 and 96: Programming PRINT TAB(2) “hello
Page 97 and 98: Inputs and Outputs 6 Inputs and Out
Page 99 and 100: Unassigned space remains in the mem
Page 101 and 102: U11 is a 74HCT138 3-to-8-line decod
Page 103 and 104: If you wish, you can wire U14’s i
Page 105 and 106: Inputs and Outputs Figure 6-4. Outp
Page 107 and 108: Inputs and Outputs Listing 6-2. Set
Page 109 and 110: The 82C55 also has CMOS-compatible
Page 111 and 112: Inputs and Outputs Pin Symbol Input
Page 113 and 114: Inputs and Outputs An 8255 Interfac
Page 115 and 116: Inputs and Outputs XBY(0FC03h)=9BH
Page 117 and 118: To set or clear a different bit, de
Page 119 and 120: 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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Each character in the CG ROM and CG
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Displays Interfacing Full control o
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Displays Listing 8-4 (page 2 0f 2).
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Displays Listing 8-5. Displays key
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Displays Listing 8-6 (page 2 of 2).
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Using Sensors to Detect and Measure
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• What power supplies are availab
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different ground symbols for the tw
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10 REM use single-ended mode 20 REM
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Clocks and Calendars 10 Clocks and
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Listing 10-1. Uses BASIC-52’s rea
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Clocks and Calendars Figure 10-1. P
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Clocks and Calendars Table 10-1. Re
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If you want an alarm frequency othe
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Clocks and Calendars Listing 10-3 (
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Clocks and Calendars Listing 10-3 (
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Control Circuits 11 Control Circuit
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the LSTTL part, and wire the desire
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Control Circuits Listing 11-1. Cont
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Control Circuits Listing 11-2. Demo
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Control Circuits disables the outpu
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Wireless Links 12 Wireless Links Wi
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Wireless Links Figure 12-2. This in
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Wireless Links Because there are th
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Wireless Links Figure 12-4. The GP1
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through the LEDs. If you prefer an
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Wireless Links Figure 12-6. Using a
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Wireless Links Figure 12-7. Using a
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Wireless Links IREDs emit energy at
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In the infrared link, the amount of
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Calling Assembly-language Routines
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into memory in the 8052-BASIC syste
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2048h in code memory. This is becau
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Binary value 1100 0101 Hex equivale
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Successful assembly is a good sign,
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statement must match the address in
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• BASIC-52’s ON EX1 instruction
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Running BASIC-52 from External Memo
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14-1 for longer delays between writ
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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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