Lab. 2 Overview. Lab. 2 and Assignment 3 Many Lab. 2 and Assignment 3 tasks involve...

Lab. 2 Overview

Lab. 2 and Assignment 3

Many Lab. 2 and Assignment 3 tasks involve “downloading” provided code, compiling and linking into a project.

When the code is run, some special characteristics of the processor are examinedWatchdog timer in a video gamePower management (speed) optional

04/21/23TDD-Core Timer Library, Copyright M. Smith, ECE, University of Calgary, Canada 2 / 28

Assignment 3

Labs. 2, 3 and 4 require the “true” speed of the processor to be known.

Download C++ code to “flash” the LED and then adjust a constant to get 1 second flash

Need to count “Processor cycles” with Blackfin 64-bit system register (CYCLES (low-32) / CYCLES2 (high 32))StartCyclesCountASM( ) and

StopCyclesCountASM( ) providedYou provide ReadCyclesCounterASM( )


Lab. 2 Task 1 Retest equipment and code

Project is provided that will retest Lab. 1 code and the Blackfin.Reuses your Lab. 1 code and your Lab. 1

TestsProject is provided that will retest your

Assignment 3 codeReuses your Assignment 3 code.Assignment 3 tests are provided


Task 2 – 6-pixel Video Game

void ExplainGame(void) { puts("\nWhen LED 1 is blinking, the aeroplane is under Blackfin control"); puts("\nTo show that the aeroplane crew is still awake"); puts("They must match the lights (LED 4, 3 and 2) on the LED panel"); puts(" by pushing the corresponding switches"); puts("LED 1 is ignored so you don't need to use SW1\n"); }


Task 2 – Video “game”

Demonstrates the concept of “waiting for input” and associated problems Main problem – other tasks can’t be done will

processor waits for your input

Tests your reaction time

Download C++ code main( ) and watchdog timer code (Friday’s lecture)

No new code needs to be developed Makes use of your Lab. 1 and Assignment 3 code


Task 2 main( )

WatchDogTimerHowled = 0; ActivateWatchDogTimer( ); // Background interrupt task while (WatchDogTimerHowled != 1) { ResetWatchDogTimer( ); GoControlTheAeroPlane( ); // Shown by blinking LED 1 CheckIfCrewAreAwake( ); // Test response time } // Should never get here unless Watch Dog Timer 'Howled' StopWatchDogTimer( ); WriteFlashLEDASM(0); CrewErrorOccurred( );


Task 3 -- OPTIONAL

Important to be able to set microprocessor into low power mode (while waiting) and then back to high speed mode (while doing things) Dynamic Power Management (Chapter 8) means

that can be done by software and not hardware changes. (Good Final Exam Q9)

SO important that can be done as a “build option” when setting up your project.


Interrupt Handling – Chief issues

Interrupts occur “randomly”The hardware must work to accept

interrupts.The interrupt service routine must work

to process the interrupts and perform the correct action

The processor must be told how to handle this random event


4 things to tackle

All 4 things must work the first timeHighly “unlikely”

Everybody using microprocessors must be able to handle interrupts and ISR

Processors have special features to make the development easier

Chief feature – software interruptsTemporarily remove the hardware from the

development process


Task 4 – Set up a test for the software up interrupt

// Hardware Manual Figure 4.5

// Get hardware interface ready

// Step 1 -- set the core event (interrupt) vector table SetVectorTableLab2Task4CPP();

// Tells the processor which ISR when interrupt occurs

// Step 2 -- set the SIC_IMASK -- system interrupt mask

// Hardware Manual Fig. 4-8 -- PF Interrupt A SetSIC_IMASKLab2Task4ASM( );

// Step 3 -- set IMASK -- Core Interrupt Mask SetIMASKLab2Task4ASM( );


Task 4 – Actual Test Code

SetVectorTableLab2Task4CPP();

SetSIC_IMASKLab2Task4ASM( ); CHECK_VALUES(numberSW4Interrupts, ==, 0);

SetIMASKLab2Task4ASM( );

StartCycleCOunterASM( ); unsigned long long int firstTimeMeasurement = ReadCycleCOunterASM( );

CauseSWI(PRETEND_GPIO_INTERRUPT);

CHECK_VALUES(numberSW4Interrupts, ==, 1);


Interrupts Key issue to remember

You can pass information to a subroutine using parameters passed in R0, R1, etcPassing parameters is possible as

subroutines occur “when you want” as part of your code.

You pass information into interrupt service routines using “semaphores” and “messages”These are “volatile” global variable


Semaphores and message to ISR

extern volatile unsigned long int numberSW4Interrupts;

extern volatile unsigned long long int ISRloggedTimeMeasurement[ ];


Interrupt service routine in C++

EX_INTERRUPT_HANDLER(GPIO_INTERRUPT) { // Make the interrupt service routine software somewhat software testable by // counting the interrupts that have occurred // and, via the LED, show the "humans" that something has occurred numberSW4Interrupts = numberSW4Interrupts + 1; WriteFlashLEDASM(numberSW4Interrupts); }


Task 5 – Hardware interrupts

InitGPIOFlags( ) -- Lab. 1SetGPIOFlagsInterruptsASM( )

Modify the FIO_MASK_A register to allow interrupts to occur when you press SW4 and not when you press the other switches

ClearIMASKLab2Task4ASM( ) is the opposite of SetIMask( ) – WHY NEEDED?

The rest of the code uses Lab. 1 code and Task 4 code


Task 6 – Improved video game

With the interrupt on SW4 working, we can now improve the “aircraft control” software to control the plane AND test the reaction time of the crew simultaneously

Down load the code, and will it auto-link to Lab. 1, Assignment 3 and other tasks


Task 7 – Light sensor

Wire up the 8 pin light sensor chip Info is printed in course notesSpecial Circuit Cellar magazine article on

using light sensor for blood oxygen sensorVcc (+5V), Ground and output

Output connects to SW4 (PF11)Other pins control

Light sensitivity (1, 10, 100)Frequency range


Task 7 – Light sensor

Check light sensor is working using oscilloscope

Light sensor outputs a +5V 50% duty cycle pulse whose frequency changes with light intensityMeasure frequency at low and high light

levels


Task 8 – Measure the light level

Design part of the lab. We are going to display the light levels in the

laboratory on a scale of 0 (dark) to 31 (brightest). The display has to respond to light levels, but the

scale does not have to be linear. (Would take too long.).

Your design to be done in C++ or ASM, your choice I provide a description of what I did Essentially a cut and paste job on the earlier tasks to change

the names of functions from Lab2Task4XXXX( ) to Lab2Task8XXXX( ) and then change 11 lines


Task 9 – Does it really work

Download the provided audio project Hook-up your ear phones and "music", and the light

sensor to PF11 on the Blackfin breakout board Compile the project DoesYourLab2CodeReallyWork

and run the code. You should be able to listen to the music and press

switches at the same time -- same as Lab. 1 Task 9 You should be able to cover the light sensor and get

the music to switch from the left channel to the right channel


Lab. 3

Replaces light sensor with temperature sensor Need to display temperature in C on the LED

screen Need to print temperature every 5 seconds

Treat as take-home lab. Quiz that is done during lab. Time One lab. Partner hooks sensor to PF10, and the

other hooks sensor to PF9


Lab. 4

I understand what is going on at the “low level” when dealing with peripherals

I would prefer NOT to code at a low level any more

Using “drivers” and “services” to do DMA activity and then send message “MERRY CHRISTMAS” to an LCD screen over an SPI interface


Lab. 2 Overview. Lab. 2 and Assignment 3 Many Lab. 2 and Assignment 3 tasks involve...

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