The Microcontroller Idea Book - Jan Axelson's Lakeview Research

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Chapter 2 printer or other serial peripheral (LPT); and generating pulses for EPROM programming (PGM PULSE). Timer 2 generates a baud rate for serial communications at SER IN and SER OUT. These are all typical applications for timer/counters in microcontroller circuits. If you don’t use the optional timer functions, you can program the timers for other applications. In addition to timing functions, where the timer increments at a defined rate, you can use the timers for event counting, where the timer increments on an external trigger and measures the time between triggers. If you use the timers for event counting, T2, T2(EX), T0, and T1 detect transitions to be counted. The serial port. The 8052’s serial port automatically takes care of many of the details of serial communications. On the transmit side, the serial port translates bytes to be sent into serial data, including adding start and stop bits and writing the data in a timed sequence to SER OUT. On the receive side, the serial port accepts serial data at SER IN and sets a flag to indicate that a byte has been received. BASIC-52 uses the serial port for communicating with a host computer. External interrupts. INT0 and INT1 are external interrupt inputs, which detect logic levels or transitions that interrupt the CPU and cause it to branch to a predefined program location. BASIC-52 uses INT0 for its optional direct-memory-access (DMA) function. Programming functions. BASIC-52’s programming commands use three additional port bits (ALEDIS, PGM PULSE, and PGM EN) to control programming voltages and timing for storing BASIC-52 programs in EPROM or other nonvolatile memory. Additional Control Inputs Two additional control inputs need to be mentioned. A logic high on RESET resets the chip and causes it to begin executing the program that begins at 0 in code memory. In the 8052-BASIC chip, this program is the BASIC-52 interpreter. EA (external memory access) determines whether the chip will access internal or external code memory in the area from 0 to 1FFFh. In BASIC-52 systems, EA is tied high so that the chip runs the BASIC interpreter in internal ROM on boot-up. Power Supply Connections And, finally, the chip has two pins for connecting to a +5-volt DC power supply (VCC) and ground (VSS). That finishes our tour of the 8052-BASIC chip. We’re now ready to put together a working system. 22 The Microcontroller Idea Book
Powering Up 3 Powering Up This chapter presents a circuit that enables you to start using the 8052-BASIC chip. You can write and run programs and experiment with the BASIC-52 programming language. Later, you can add non-volatile memory for permanent program storage and interfaces to displays, keypads, and whatever else your projects require. About the Circuit Figure 3-1 contains all of the components you need to get a BASIC-52 system up and running, plus a few optional extras for future use. Table 3-1 is a parts list for the circuit. The circuit has five major components: the 8052-BASIC chip (U2), an address latch (U4), an address decoder (U6), static RAM (U7), and an RS-232 interface (U5). As I’ll explain below, a few of the components aren’t essential at this point, but I’ve included them to allow easy expansion later on. The circuit configuration is a more-or-less standard design, similar to many other microcontroller circuits. When you understand this circuit, you’re well on your way to understanding many others. The following paragraphs explain the circuit operation, component by component. If you’re impatient to get started, you can skim or skip over this section for now, and go straight to the construction details. The Microcontroller Idea Book 23
Page 1 and 2: The Microcontroller Idea Book Circu
Page 3 and 4: Table of Contents Chapter 1 Microco
Page 5 and 6: Chapter 11 Control Circuits 185 Swi
Page 7 and 8: Introduction Introduction This book
Page 9 and 10: A chapter on assembly-language inte
Page 11 and 12: Microcontroller Basics 1 Microcontr
Page 13 and 14: But along with cheap, powerful, and
Page 15 and 16: makes sense. For simpler designs, a
Page 17 and 18: 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: Inside the 8052-BASIC Code and data
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 and 70: Saving Programs Figure 4-5. Additio
Page 71 and 72: problems with EPROMs that have a 10
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
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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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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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Page 279 and 280:
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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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