hc11 architecture

8/4/2019 HC11 Architecture

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Motorola HC11

Fun with Microcontrollers andEmbedded Systems


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Microcontrollers

What is a microcontroller?

A processorUsually not cutting edgeDependable

All major bugs well knownPredictable

Critical for real-time processingOn-chip peripherals and memory

Parallel and serial digital I/OAnalog I/OCounters and timersInternal ROM and/or EPROM


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What are microcontrollers used in? Watches Microwaves Stereo Receivers

Some products that you might know:NASAs Sojourner Rover 8-bit Intel 80C85 Palm Vx handheld 32-bit Motorola Dragonball EZ

Sonicare toothbrush 8-bit Zilog Z8 The Vendo V-MAX 720 Soda Machine Motorola HC11 Miele dishwasher 8-bit Motorola 68HC05 Hunter 44550 Programmable Thermostat 4-bit processor

Microcontrollers


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Microcontrollers

Microcontroller unit sales are 15x higher thanmicroprocessors. and are MUCH cheaper.


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Microcontrollers

Microcontrollers are a large market

8-bit controllers are the largest, but not growing the fastest.


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Microcontrollers

8-bit microcontroller growth rate for 2003 is at 9.42%.

Microcontroller growth rate in general is 11.5%.

8-bit controllers loosing market share in 2003. Was62.36% in 1998 to 56.76% in 2003.

16- and 32-bit and higher are on the rise. They willdouble their unit market share from 15.11% in 1998 to31.56% in 2003, decreasing 4-bit and 8-bit devices.

But, in 2003, the 8-bit microcontrollers will outnumberthe higher bit units by almost 80% in the market place.

Source: Cahners In-Stat Group


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Microcontrollers

So what languages are they being programmed in?

Assembly ~ 21% ~ 10%

C ~ 69% ~ 80%

C++ ~ 5% ~ 6%

Java ~ 1 % ~ 2%

Other ~ 3 % ~ 2%

1998-1999 1999-2000

Source: TRON Association Survey 1998/99 & 1999/2000


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HC11

Motorola 68HC11M6801 processorROM (8KB), EEPROM (512B), RAM (256B)Counter/Timer system

A/D converterD/A in kitParallel I/OExpansion bus

To add more memory

Serial communication


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HC11

HC11 Architecture


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HC11 CPU


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HC11 CPU

Condition CodesNot present for MIPS integer instructionsSingle-bit flags set appropriately for most instruction(several instructions do not, including push and pop)

C Carry/BorrowV OverflowZ ZeroN NegativeH Half-Carry

MAL code HC11 code What it does

bge $t0, 4, mylabel cmpa #4 Subtract AccA - 4, set CCR

bge mylabel Branch if

(CCR[Z]=1 OR CCR[N]=0)


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HC11 CPU

Command RegisterBits set by the user to tell the processor how to dothings

I Interrupt MaskX XIRQ maskS Disable STOP instructions


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HC11 Instructions

HC11 Instructions have variable lengths (not like MAL)Careful coding can keep applications small and able tofit in the EPROM

We dont have to worry about this since were usingExpansion Mode: there is extra memory in the microkits.

The opcode is always 1 byteAn additional 0-3 bytes specify the data to work with


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HC11 Addressing

Addressing ModesMIPS (TAL) has:

HC11 has severalCheck opcode listings to see what modes workwith what instructions

And what condition codes are set


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HC11 Addressing

Inherent addressingOpcode fully specifies operation; no addressingExamples:

INCB increment accumulator BASLA Arithmetic Shift Left accumulator APSHYPush index register Y onto stack


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HC11 Addressing

Immediate addressing1 or 2 byte immediate depending on register involved(LDAA vs. LDD)ALWAYS include a #Several formats for different bases -- C-styleconstants instead of what is in the HC11manual (dont use !,$,@,%)

Decimal: LDAA #245

Hexadecimal: LDAA #0x61Octal: LDAA #041Binary: LDAA #0b11000011ASCII: LDAA #a


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HC11 Addressing

Direct and enhanced addressing

Access an absolute memory locationEssentially the same mode, but with 8-bit (direct)or 16-bit (enhanced) addressesThe assembler will decide on which to use based

on how many bits are neededExample

// Your data starts at address 0x4000:.sect .datavar: .word 0x1000 // Allocate/initialize a wordvar1: .word 0xffff // Note: a word is 16 bits!

.sect .textSUBD var // Subtract [var] from D

SUBD 0x4000 // Subtract [var] from D


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HC11 Addressing

Indexed addressingUses index register X or YSimilar to MAL lw $t0, 4($sp)

But can access memory and use it all at once!!Example

#define mydef 4 // cc preprocessor usedldx #var // Like MAL load address

addd 0,X // add contents of 0($X) to D// (Note addd X doesnt work)addd 2,X // add contents of 2($X) to Daddd mydef*2, X // add contents of 8($X) to D


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HC11 Addressing

Relative addressingUsed for branches by the assemblerOffsets from128 to +128 bytesUse jumps for longer branches


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HC11 Instructions


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HC11 Instructions


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HC11 Example

/************************************************************ Program 1.* A simple program to introduce the 68HC11 environment***********************************************************/

#include // sets stuff up for you, especially I/O

.sect .data

SIGNON: .asciz CMPE12C SimulatorPROMPT: .asciz >

// (continued)


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HC11 Example Continued

/************************************************************** Your program starts where indicated by the label main. After startup* Code in v2_18g3.asm is done, it jumps to this label and continues running.**************************************************************/

.sect .text

main:ldx #SIGNONjsr OUTSTRING

loop: ldx #PROMPT // address of promptjsr OUTSTRING // write out to serial communications

// interface (to PC)jsr GETCHAR // get a character from SCI, returns in Ajsr OUTCHAR // write A to the SCIjsr OUTCRLF // write CR/LF to SCIjmp loop


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Micro Kit Usage

Design environment:Edit & assemble on CATS machines

> hc11build file.asmDownload program to the PC

Upload to the microkit using serial cable

To use kits at home9-12V AC adapter

Serial download cableConnection to CATS machinesFree serial communication software (e.g. TeraTerm)


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Micro Kit Usage

Always #include as part of your programSets up memory, including stack pointer

Jumps to your main labelAlso includes a basic library of I/O routinesTake a look at it!/afs/cats/courses/cmpe12c-rph/include/v2_18g3.asm


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Example recursive routine

Fibonacci on the switches and LEDs

/* Input: A. Returns Ath Fibonacci term in accumulator A */fib: cmpa #2

bgt fibnot1ldaa #1 // return 1 if n


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HC11 Summary

Microcontrollers are great little machines for dataI/O and data manipulationThe CISC-style programming makes ASM programmingeasierVariable instruction length can be a problem for

Word-aligned machinesSuper-scalar machinesPipelines

The RISC philosophy is toUse simple instructions and let the compiler optimize

Use loads and stores to support higher-speed registersNeither RISC, its CISC predecessors, nor CISCY RISC hasthe definitive advantage

Depends on application, architecture, and implementation.

hc11 architecture

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