ECE372Prelabs

Clemson ECE Laboratories

ECE 372 – Microcomputer

Interfacing Laboratory

1

Pre-labs for ECE 372

Created by Ryan Mattfeld 12/17/12

Last Updated:12/17/12


2


Instructor Information and Syllabus

•

Instructor Name: Nilim Sarma

•

Email: nsarma@clemson.edu

•

Office Hours: Email to set up appointment.

•

Lab Manual can be found at http://www.clemson.edu/ces/departments/ece/resourc es/lab_manuals.html

3


Introduction

Objective:

•

Gain a better understanding of the functionality of a microcontroller.

•

Learn to interface devices with different modules on a microcontroller.

4

Experiments:

10 experiments involving various modules and a final design project.


Final Design Project

•

Will combine at least two of the labs performed throughout the semester in a creative way

•

Worth 30% of final grade

•

Weekly Lab Reports for reference when making final design

•

Final lab report will be given on final design project

5


Equipments

•

The National Instruments ELVIS system .

•

Freescale MCU Project Board Student Learning Kit –

Prototyping board with microcontroller interface.

•

Microcontroller - Freescale HCS12 Family, model

MC9S12DT256.

6 http://www.clemson.edu/ces/departments/ece/resources/ lab_manuals.html


Software Development Environment.

CodeWarrior IDE.

•

Text Editor for writing code.

•

Cross compiler to generate executables.

•

Loader program to load the executable on the microcontroller.

•

Debugger to perform runtime debugging.

7


Prerequisite

•

Familiarity with C programming language.

•

C tutorial available in lab manual.

8


Freescale Board Connector J1

9


Mandatory Safety Video

10


LABORATORY 1 –

INTRODUCTION TO THE

MC9S12DP256B

11


Laboratory 1 Program

•

Program will count from 1-16 in binary using LEDs and in decimal using the LCD display.

•

Download the program from our section on

Blackboard under the “information” section

•

Extract the program to your student (U:) drive

• Open the “Lab 1” folder and open the .mpc file to edit the program

•

Take a few minutes to read the code and figure out what it should do

12


Laboratory 1 Program

•

Make sure to turn on both power switches on the NI-

ELVIS board and connect the USB cables

•

Attempt to compile the code (ctrl+F7 is keyboard shortcut)

•

Identify and fix the error

• Hit the “debug” button (green arrow with helicopter)

•

Run the code and see the result

•

Modify the code to count backwards

13


Final Reminders!

•

Store each lab as a separate file on your student server (copying an old lab folder and renaming it for new labs)

•

This ensures all necessary files are linked and provides your access to your previous lab code when you begin your final design project.

•

You can also access your student drive from any computer with internet access at:

• https://netstorage.clemson.edu/

•

Read over Lab 2 in the lab manual to be prepared for next week!

14


LABORATORY 2 – READING

AND WRITING USING RAM

15


Device Memory Map

$0000 - $03FF – Registers.

$0000 - $0FFF – 4K Bytes EEPROM.

$1000 - $3FFF – 12K Bytes RAM.

External Memory

$FF00 - $FFFF – Vectors.

After reset the bottom 1k of the EEPROM ($0000 - $03FF) are hidden by the register space.

Refer to MC9S12DT256 Device User Guide.

16


Laboratory 2 Preparation

•

Find the folder for Lab 1 that you used last week

(stored on your student drive)

•

Copy the folder and rename it for Lab 2

•

Open the .mpc file to edit and compile your code

•

In main.c, leave the header files and #pragma statement, but delete all code in void main(void)

•

We will define a command to read and write to the

RAM of our microprocessor

•

** We will begin writing at reading at memory location ***insert location here***

17

Laboratory 2 Code


•

We will create an easy method to access specific

RAM memory addresses by using a #define statement

•

#define _P(ADDRESS) *(unsigned char volatile *)(ADDRESS)

18

•

This command will allow you to both read and write to a specific address in RAM.

•

Conceptually, in your program, you can use

•

_P(**desired memory address**)

•

Like you would use a variable to store and use information.

Laboratory 2 Code


•

Program goal: Write **** insert phrase here **** to

RAM, then read from RAM to the LCD

•

At the beginning of your program, make sure you initialize the LCD using “LCDInit()”

•

Then, make sure that after every 8 characters you clear the LCD using “LCDClearDisplay()”

•

You can write to the LCD using the command

“LCDPutChar()”

•

Use loops to write the phrase

•

Use conditional statement to clear display

19


Preparations for Next Week

•

Before next lab, read over Lab 3 in your lab manual,

Application of a Digital Latch.

20



APPLICATION OF A DIGITAL

LATCH

21

Lab 3 Preparation


•

Find the folder for Lab 2 that you used last week

(stored on your student drive)

•

Copy the folder and rename it for Lab 3

•

Open the .mpc file to edit and compile your code

•

This lab combines hardware with software

•

Uses 74LS374 Flip-Flop chip (D Flip-Flop)

22


74LS374 – D Flip Flop

•

Latch data from Input Pin to Output Pin when there is a rising edge on Clock Pin.

23


Laboratory 3 - Hardware Prep

•

The Input, 1D corresponds to the output, 1Q.

Reference chip diagram:

•

Input: Switches (SW1 1 and SW1 2)

•

Output: LEDs (LED 1 and 2)

•

Intermediate Output (Port B LEDs)

(Port B is hardwired to 4 LEDs)

•

Wire SW1 1 to 1D, SW1 2 to 2D

•

Wire 1Q to LED 1, 2Q to LED 2

24


Laboratory 3 – Microcontroller Comm.

•

Must wire inputs to microcontroller to manipulate input with code.

•

Wire SW 1 to PTT 0 (reference page 50 in lab manual for Port wiring table)

•

Wire SW 2 to PTT 1

•

Clock Pulse Input: Pushbutton (PB1) to Port M 1

•

Clock Pulse Output: Port M 0 to clock of Flip-Flop

25

•

Wiring complete!


Laboratory 3 – Software Prep

•

To use input and output registers on the microcontroller, must designate them for input or output in code.

•

DDR – Data Direction Register (0 for input, 1 for output)

•

Will use Port T, channels 0 and 1 for input, so we will set DDRT = 0x00;

•

Will use LEDs hard wired to Port B for output.

•

LEDs wired to Port B channels 4-7, set DDRB=0xF0;

•

Will use Port M channel 0 as input and Port M channel 1 as output, set DDRM = 0x01

26


Laboratory 3 – Main Function

•

Constantly loop, looking for switch input. Port T 0 and Port T 1 will change between 00, 01, 10, 11 based on switch configuration.

•

For each possible state of Port T, light corresponding

LEDs (set Port B to appropriate values)

(HINT: Port B 4-7 are wired to LOW active LEDs)

•

Finally, must generate clock pulse for D Flip-Flop

•

Check if Port M channel 1 is 0 (Push Buttons are low active). If it is, generate clock pulse on Port M channel 0. (Set PTM = 0x01 then reset it to 0x00)

27


Result

•

When complete, should have two displays:

•

1) When you flip one of the switches, the LEDs hard wired to Port B should immediately change

•

2) When you push Pushbutton 1, the switch values will travel through the Flip-Flop, and light the LEDs you wired your outputs to.

28

Flowchart


29



•


Keypad Interfacing

30


LABORATORY 5 – KEYPAD

INTERFACING

31


Laboratory 5 Hardware Prep

•

Plug in Keypads with brass side of connector facing left

•

Keypad 1



Port T 1

•

Keypad 2



Port T 2

•

Keypad 3



Port T 5

•

Keypad 4



Port T 3

•

Keypad 5



Port T 6

•

Keypad 6



Port T 7

•

Keypad 7



Port T 4

•

Keypad 8



Port T 0

32


Keypad Description/Operation

33


Laboratory 5 software prep

•

Set Port T channels 0-3 as output and channels 4-7 as input using DDRT

•

New registers: PERx (Pull Enable Register) and

PPSx(Polarity select Register)

•

PER and PPS work together to pull desired ports either high or low.

•

Pull Port T channels 4-7 high.

•

Enable Port T channels 4-7 for pulling(PERT = 0xF0)

•

Pull Port T channels 4-7 high (PPST = 0x00)

(setting PPST to 0 pulls corresponding channel high)

34


Laboratory 5 Software Tools

•

Arrays can make keyboard interfacing easier:

• unsigned char mask[16]={0xEE,0xDE,0xBE,0x7E,

0xED,0xDD,0xBD,0x7D,

0xEB,0xDB,0xBB,0x7B,

0xE7,0xD7,0xB7,0x77};

• unsigned char key[16]={'D','1','2','3',

'A','4','5','6',

'B','7','8','9',

'C','*','0','#'};

35


Laboratory 5 Code Flow Chart

START

INITIALIZE (proper header files, declarations, and definition)

No

DETERMINE IF A SPECIFIED

COLUMN IS ACTIVE IN THE

ACTIVE ROW

INITIALIZE PORT T

TURN ON 1 ROW AT A TIME

36

Yes

SEND THE PRESSED KEY TO THE

LCD DISPLAY



•


Interrupts

37



INTERRUPTS

38


Laboratory 4 Wiring Diagram

Port P 0

+5V

Port P 1

Gnd

39


Laboratory 4 Software Prep

•

INPUTS

•

Port P 0 and 1 should be used as interrupts

•

Port P generates interrupt vector 56 (reference lab manual page 51 for vector interrupt table)

•

Registers:

•

DDRP = 0x00; (interrupts are inputs)

•

PERP = 0x03; (Enable pulling for interrupt channels)

•

PPSP = 0x03; (Pull low so high active button will trip interrupt)

•

PIEP (Port Interrupt Enable Register) = 0x03; (This enables Port P 0 and 1 as interrupts)

40



•

OUTPUTS

•

LEDs hard wired to Port B will be outputs

•

DDRB = 0xF0; (Channels 4-7 are wired to the LEDs so they should be outputs)

•

LCD will constantly count from 0-9

•

LCDInit();

•

LCDClearDisplay();

41



•

LOGIC

•

Constantly loop to count from 0-9 on the LCD display

•

Create interrupt function (using interrupt 56, the interrupt vector corresponding to Port P)

–

Check PIFP to see which interrupt was triggered

–

Light LEDs to reflect which interrupt was triggered

–

Reset Port P flags by setting the PIF(Port Interrupt

Flag) register to a 1 for each channel you want to reset

42


Laboratory 4 Code Flow Chart

43



•


Rotary Pulse Generator

44


LABORATORY 7 – ROTARY

PULSE GENERATOR

45


Laboratory 7 Wiring Diagram

Rotary Pulse Generator

Port P 0

Port J 7

46



•

INPUT

•

Port P 0 and Port J 7 are interrupts wired to Output A and Output B

•

Rotate Right



Increase position

•

Rotate Left



Decrease position

•

Change in voltage produces interrupt

•

Can determine which direction

Rotary Pulse Generator turns based on interrupt and state of

Port P 0, Port J 7

47



•

INPUT

•

Interrupt Vector for Port P

•

Interrupt Vector for Port J

•

Two interrupt functions

•

Set Port P 0 and Port J 7 as inputs

•

Set PERP and PERJ to enable

Port P 0 and Port J 7 for pulling

48



•

OUTPUT

•

Port B LEDs will be used to show rotation in rotary pulse generator

•

Set Port B 4-7 as output

•

Initialize Port B LEDs off (Low Active)

49



•

LOGIC

•

Pulling registers high and low is essential

•

Interrupt trigger requires voltage change

•

As pulse generator rotates, voltage changes from low to high and high to low.

•

Pull high if next voltage change is high

 low

•

Pull low if next voltage change is low

 high

50



•

LOGIC

•

In each interrupt function:

•

Determine which position the switch is in

•

Set LEDs to light such that rotating right causes the

LEDs to “scroll” up and rotating left causes the LEDs to “scroll” down

51


Laboratory 7 Flow Chart

52



•


Clock Pulse Generator

53


LABORATORY 8 – CLOCK

PULSE GENERATOR

54


Laboratory 8 Hardware Preparation

•

The buzzer is hardwired to Port T 0, so no wiring is required!

•

(Quick note generation review)

55



•

LOGIC

•

Introduction to the Enhanced Capture Timer

•

Input Capture

•

*Output Compare*

•

Enable ECT: TSCR1 (Timer System Control

Register 1) Bit 7 (Enable bit) set to 1

•

TIOS (Timer Input capture/Output compare Select)

Set to 1 for Output Compare

56



•

LOGIC

•

Initialize: DDRT (Port T 0 is our output to the buzzer)

•

TCNT holds current clock time

•

TC1 holds our target clock time (when time is reached, flag is tripped)

•

TFLG1_C1F is our flag

•

TFLG1 = TFLG1_C1F_MASK; resets timer flag

•

Invert voltage from Port T 0 when timer flag is tripped

•

Allows control based on real time

57



•

LOGIC

•

Initialize our target time (TC1) to the current time

(TCNT)

•

For a certain note length (quarter note, eighth note, etc)

• Add the note’s period (in microseconds) to target time

•

Wait until timer flag is tripped

•

Invert signal to buzzer (through Port T 0)

58


Laboratory 8 Software Flow Chart

59



•


Pulse Width Modulation

60


LABORATORY 11 – PULSE

WIDTH MODULATION

61


Laboratory 11 PWM Lab Description

•

Pulse Width Modulation allows us to control the duty cycle of a signal

•

Can be used to control motor rotation speeds

•

Using our board, we must amplify the current in order to power our motor (current driver chip)

•

Control speed of our motor using interrupts to control duty cycle

•

Display duty cycle on LCD

62


Laboratory 11 PWM Description

63


Laboratory 11 PWM Description

64


Laboratory 11 PWM Registers

•

PWMEx – Pulse Width Modulation Enable

•

PWMPOLx – PWM Polarity Register (one for each

PWM channel, if 1 - starts high at each period, if 0 – starts low)

•

PWMCLKx – PWM Clock Select Register (1- SA or

SB, 2- A or B) --- Note: channels 0,1,4,5 use A/SA and channels 2,3,6,7 use B/SB

•

PWMCAEx – PWM Center Align Enable Register

(1- Center Aligned, 0- Left Aligned)

65


Laboratory 11 PWM Registers

•

PWMPRCLK – PWM Prescale Clock Select Register

(6-4 select prescaler for B, 2-0 select prescaler for A)

•

PWMSCLA – PWM Scale A Register

•

(Clock SA = Clock A/(2*PWMSCLA))

•

PWMPERx – PWM Channel Period Registers

•

(PWMx Period = Channel Clock Period*(2*PWMPERx)

•

(HINT: bus clock = 25 MHz)

66


Laboratory 11 PWM Final Registers

•

PWMDTYx = PWM Duty Register

•

If Polarity (PWMPOL) = 1,

•

Duty Cycle = (PWMDTYx/PWMPERx)*100

•

If Polarity (PWMPOL) = 0,

•

Duty Cycle = ((PWMPERx-PWMDTYx)/PWMPERx)*100

67


Laboratory 11 Hardware Preparation

•

62003 Current Amplifier

•

Wire GND to ground and Common to +5V

•

Output of current amplifier goes to the black motor wire

•

Red wire from motor goes to 3.3V on NI-ELVIS board

•

Wire PWM1 (pin can be located in chart on page 50 of manual) to the input of current amp

68


Laboratory 11 Software Preparation

•

Initializations

•

Port P 1 (which corresponds to PWM 1) set to output

•

Port J 7 will be the interrupt used to control duty cycle

•

PIEJ set to turn on Port J 7 as interrupt

•

PERJ, PPSJ set to pull Port J 7 to high voltage (push buttons are low active)

•

EnableInterrupts;

•

LCDInit(); (will display motor duty cycle on LCD)

69


Laboratory 11 Software Goals

•

When interrupt detected (pushbutton pressed)

–

Increment duty cycle by 25%

–

When duty passes 100%, reset it to 0%

•

Display current duty cycle on LCD display

70



•


Serial Communications (SCI)

71


LABORATORY 6 – SERIAL

COMMUNICATIONS (SCI)

72


Laboratory 6 Description

•

Serial Communication Simulation (no communication with NI-ELVIS board at all)

•

Will use simulation to read in keyboard entry, alter it in code, and send it back out to terminal

•

Simulation can accurately simulate registers with proper set up.

•

Create structures and definitions to make register simulation easier

73


Laboratory 6 Definitions

#define SCI_ADDR 0x00C8

Typedef struct{ unsigned char SCIBDH; unsigned char SCIBDL; unsigned char SCICR1; unsigned char SCICR2; unsigned char SCISR1; unsigned char SCISR2; unsigned char SCIDRH; unsigned char SCIDRL;

} SCIStruct;

#define SCI (*((SCIStruct*)(SCI_ADDR)))

74


Laboratory 6 Initializations

•

SCIBDH and SCIBDL – SCI Baud Rate High and

Baud Rate Low registers (used to set baud rate)

•

SCI baud rate = SCI module clock/(16*BR)

•

BR = total of 12 bits from SCIBDH and SCIBDL:

0000 HHHH LLLL LLLL

•

Question: If module clock has speed of 8MHz, what should SCIBDH and SCIBDL be to produce a target baud rate of 9600 Hz.

75


Laboratory 6 Initializations

•

SCICR1 = 0x00

•

SCICR2 = 0x0C (sets transmitter enable bit (bit 3) and receiver enable bit (bit 2))

•

SCISR1 is used to detect when data is sent and received.

•

SCISR1 bit 7



Transmit Data Register Empty Flag

•

SCISR1 bit 5



Receive Data Register Full Flag

•

SCIDRH and SCIDRL store data for transmitting and receiving. Because we set SCICR1 to 0x00, we only have 8 bits of data (SCIDRH is not used)

76


Laboratory 6 Software

•

Create two functions, one to write to the terminal and one to read keyboard input:

•

Char TERMIO_GetChar(void)

–

Wait until data received (using SCISR1)

–

Return received character (using SCIDRL)

•

Void TERMIO_PutChar(char ch)

–

Wait until ready to transmit (using SCISR1)

–

Send character to terminal (using SCIDRL)

•

In main, convert received character from lowercase to uppercase (use ASCII table)

77



•


A/D and D/A Conversion

78


LABORATORY 9/10 – A/D AND

D/A CONVERSION

79


Laboratory 9/10 Description

•

We will read in an analog signal from the function generator and read it into our microprocessor through a built in Analog to Digital Converter

•

The ATD Converter converts the signal by sampling it at a specified rate and estimating the value by quantizing it

•

We then send the digital signal out and use an external Digital to Analog converter to send the signal to the oscilloscope

80


Laboratory 9/10 Hardware Preparation

81


Laboratory 9/10 SPI Registers

•

SPI (Serial Parallel Interface) allows communication with external devices (DTA converter, here)

•

SPICR1 = 0x50; (Sets SPI Control Register 1 bits 6 and 4. Bit 6 enables SPI, Bit 4 sets SPI as master)

•

SPICR2 = 0x0000; (disables a number of unneeded features)

•

SPI1BR = 0x00; (SPI Baud Rate Register)

82


Laboratory 9/10 ATD Registers

•

ATD0CTL2 = 0x80 (enables internal ATD converter)

•

ATD0CTL3 = 0x40 (Sets to take 8 conversions per sequence)

•

ATD0CTL4 = 0x0000 (Sets 10 bit resolution and sets sample rate as high as possible)

83


Laboratory 9/10 Software

•

Port M channel 0 is used as a sync pin for the DTA converter chip. (Will be used as output)

•

Set DDRM = 0x03;

•

Create main loop to constantly read in data, convert it for writing, and then write it to the DTA converter.

•

While loop

–

Prepare ATD for data

•

ATD0CTL5 = ATD0CTL5_DJM_MASK;

–

Wait until data is read (Sequence Complete Flag)

•

While(ATD0STAT0_SCF == 0);

–

Prepare and Send Data

84



•

Preparing Data

•

Data Received as 10 bits from ATD

ATD0DR0H ATD0DR0L

0000 00AB CDEF GHIJ

•

Data Trasmitted through SCI as 12 bits, so desired output looks like this:

0000 ABCD EFGH IJ00

•

In order to maintain uppermost bits, must shift bits.

<< (shift bits left) >> (shift bits right)

& (binary AND) | (binary OR)

85



}

{

•

Sending Data volatile char temp; void write_dac(char upperbyte, char lowerbyte)

PTM = 0x00;

SPI1DR = upperbyte & 0x0F; while(SPI1SR_SPTEF == 0);

SPI1DR = lowerbyte; while(SPI1SR_SPTEF == 0); temp = SPI1SR; temp = SPI1DR;

PTM = 0x03;

86


Laboratory 9/10 Function Generator

87



•

Next week begins Final Design Project week. It will help to prepare your code before working on your design project next week.

88


References

•

Images provided from ECE 372 lab manual and user’s manual for MC9S12DT256 and from personal notes.

89


THE END

90

ECE372Prelabs

ECE 372 – Microcomputer

Interfacing Laboratory

LABORATORY 1 –

INTRODUCTION TO THE

MC9S12DP256B

LABORATORY 2 – READING

AND WRITING USING RAM

LABORATORY 3 –

APPLICATION OF A DIGITAL

LATCH

LABORATORY 5 – KEYPAD

INTERFACING

LABORATORY 4 –

INTERRUPTS

LABORATORY 7 – ROTARY

PULSE GENERATOR

LABORATORY 8 – CLOCK

PULSE GENERATOR

LABORATORY 11 – PULSE

WIDTH MODULATION

LABORATORY 6 – SERIAL

COMMUNICATIONS (SCI)

LABORATORY 9/10 – A/D AND

D/A CONVERSION

THE END

Related documents

Products

Support

ECE372Prelabs

ECE 372 – Microcomputer

Interfacing Laboratory

LABORATORY 1 –

INTRODUCTION TO THE

MC9S12DP256B

LABORATORY 2 – READING

AND WRITING USING RAM

LABORATORY 3 –

APPLICATION OF A DIGITAL

LATCH

LABORATORY 5 – KEYPAD

INTERFACING

LABORATORY 4 –

INTERRUPTS

LABORATORY 7 – ROTARY

PULSE GENERATOR

LABORATORY 8 – CLOCK

PULSE GENERATOR

LABORATORY 11 – PULSE

WIDTH MODULATION

LABORATORY 6 – SERIAL

COMMUNICATIONS (SCI)

LABORATORY 9/10 – A/D AND

D/A CONVERSION

THE END

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