A outline of what's in the test.

The test will be in our normal classroom on Wednesday 10th June at 10:14am

There will be a picture of an Arduino like this below and you'll annotate it with text and arrows. You may be asked to identify a crystal, capacitor, resistor, LED or voltage regulator too.

There will be one of the two pages from the Atmel mega 328 family's data pdf. You'll be required to comment on some of the functions in the page below and most of the features in the very front page.







There will be questions about a schematic involving the Arduino like the one below.

There's a clearer copy of this in a pdf on our Moodle page.

Test Information

There will be a theory test on Thursday 10 June. It will be closed book and you must complete it in 1 hour and 45 minutes. We will discuss some of the items in the test on the previous class.

There will be a question on the main parts of the Arduino. See the labelled diagram above. This is not exactly the same as our Arduino but, apart from the DIL processor and colour, is pretty close.

There will be a question on the page above called The Front Page of the Mega328. You will be expected to write a sentence explaining some of the features listed. 

There will be questions on the functions diagram of the Mega328. You will be given a copy of this diagram and be expected to write a short paragraph on up to three blocks.

There will be a question about the Arduino schematic diagram above or similar.

Also there's buggy program. A program will be given to you with errors in it. You will have to identify the errors. Mostly syntax violations.

A problem to do with sampling real world inputs will be given and you will be asked how you would respond to this using the Arduino.

You will be asked to write a simple assembly language program. You will be asked to write a program in Arduino C.

There may be other questions but only on items we have studied in class including serial buses, pin outs of the Arduino and the mega328p, voltage dividers, the stack and interrupts.

Please contact me about any problems. Good luck.

PeterB

Pulse width modulation

Good simulation vid

The Arduino page on analogWrite() here

You can use pwm to control higher voltages like here.

i2c Bus

Most popular of the serial buses. Uses one wire for clock and one wire for bidirectional data. Based on Phillips' iic network. Lots of chips use the i2c protocol.

Good short introduction here. Not Arduino based.

Using i2c to connect arduino to eeprom chip that holds 256k bits, here.

Interesting use of i2c OLED display.

SPI or i2c. Which one is ""better"?

Arduino descriptive diagram. DIL version of Rev 3

Arduino Uno Schematic

A good introduction to reading a schematic

The SPI bus

Fastest of the serial I/O on the Arduino.

A good tutorial on spi using a digital potentiometer chip here

A tutorial on the spi bus, more technical here

Two Arduino's connected via spi here. Code via link to github.

Using hex files from AVR studio to program Arduino

Programs needed are just AVR Studio and avrdude. I used AVR Studio version 4.14 and the avrdude that came with the Arduino suite.

Step 1. Write your program in assembler in AVR Studio, build then save the hex file.
Step 2. Go into the command prompt and invoke avrdude with the right switches.

I started with the usual Arduino C blink program, just to make sure I got the COM port right and to see the hardware was all working. Then did steps above.

Below are some relevant screen shots.

Blink for AVR Studio 4 assembler


.include "m328pdef.inc"


;Based on http://www.robertoinzerillo.com/wordpress/?p=5
;-----------------------------------------;
; FIRST WE'LL DEFINE SOME REGISTER TO USE ;
;-----------------------------------------;
.DEF A = R16   ;GENERAL PURPOSE ACCUMULATOR
.DEF I = R21   ;INDEXES FOR LOOP CONTROL

.ORG $0000

;-----------------------------------------;
; FIRST WE SETUP A STACK AREA THEN SET    ;
; DIRECTION BIT ON PORT-B FOR OUTPUT/SPKR ;
;-----------------------------------------;
START:
  LDI A,LOW(RAMEND)   ;SETUP STACK POINTER
  OUT SPL,A           ;SO CALLS TO SUBROUTINES
  LDI A,HIGH(RAMEND)  ;SETUP STACK POINTER
  OUT SPH,A           ;SO CALLS TO SUBROUTINES

  LDI A,0b1111_1111   ;SET ALL PORTB FOR OUTPUT
  OUT DDRB,A          ;WRITE 1s TO DIRECTN REGS

;--------------;
; MAIN ROUTINE ;
;--------------;
LEDONOFF:
  SER A
  OUT  PORTB,A
   RCALL DELAYLONG
  CLR A
  OUT PORTB,A
   RCALL DELAYLONG
  RJMP LEDONOFF


DELAYLONG:
; =============================
; Delaying approximately 1 sec at 8Mhz.
; This code has been created with  “AVR Delay Loop Generator V1.2?.
          ldi  R17, $48
WGLOOP0:  ldi  R18, $BC
WGLOOP1:  ldi  R19, $C4
WGLOOP2:  dec  R19
          brne WGLOOP2
          dec  R18
          brne WGLOOP1
          dec  R17
          brne WGLOOP0
; =============================
RET

Each AVR assembler instruction has its own help page with example.

Each op code has an explanation via the help screen

You can also go to the Atmel AVR assembler site and look at instruction like SER.

Port Input and Output

All AVR devices, like our Mega328, have ports. Usually they are a group of 8 pins that send or receive binary to or from the outside world.

There are three registers associated with each port.

1. The output register PORTX
2. The input register PINX
3. The data direction register DDRX.

For instance port B is made up of 8 pins PB0, PB1, PB2 ....PB7. It has three associated registers:

1. PORTB
2. PINB
3. DDRB

These registers live in the I/O register space just above the 32 general purpose registers.

Some good port pages:
Useful but about GCC.
Some good stuff here.

There are four sorts of memory on the avr devices like the mega328

Setting up the stack before using subroutines

The code for the above program is:

.include "m328pdef.inc"
start: ;set up the stack
ldi r16, low(RAMEND)
out SPL, r16
ldi r16, high(RAMEND)
out SPH, r16

nop

call below
nop

finish: rjmp finish
below:
ldi r17,$99
ret

The relevant part of the def.inc file the shows what RAMEND is for this processor is:

; ***** CPU REGISTER DEFINITIONS *****************************************
.def XH = r27
.def XL = r26
.def YH = r29
.def YL = r28
.def ZH = r31
.def ZL = r30



; ***** DATA MEMORY DECLARATIONS *****************************************
.equ FLASHEND = 0x3fff ; Note: Word address
.equ IOEND = 0x00ff
.equ SRAM_START = 0x0100
.equ SRAM_SIZE = 2048
.equ RAMEND = 0x08ff
.equ XRAMEND = 0x0000
.equ E2END = 0x03ff
.equ EEPROMEND = 0x03ff
.equ EEADRBITS = 10
#pragma AVRPART MEMORY PROG_FLASH 32768
#pragma AVRPART MEMORY EEPROM 1024
#pragma AVRPART MEMORY INT_SRAM SIZE 2048
#pragma AVRPART MEMORY INT_SRAM START_ADDR 0x100



; ***** BOOTLOADER DECLARATIONS ******************************************
.equ NRWW_START_ADDR = 0x3800
.equ NRWW_STOP_ADDR = 0x3fff
.equ RWW_START_ADDR = 0x0
.equ RWW_STOP_ADDR = 0x37ff
.equ PAGESIZE = 64
.equ FIRSTBOOTSTART = 0x3f00

Assembler delays

Using delays in AVR studio

Write a variation on the above program to produce any delay required for your project.

AVR Studio and assembly language.

You'll need to download AVR Studio 4.19 for further work on AVR assembly language.

RS232 protocol

The RS232 protocol has been around for many years now. There are various versions and we have to be aware that non-standard applications are used often. The main aspects are the sockets and plugs and the packet sending rules.

Think about the wearable project

The next project is about using an embedded system very close to a person. It could be on clothes, shoes or on something you carry or on an accessory like a coat, hat or belt. Some ideas below are given in links.

Links


http://atmelcorporation.wordpress.com/2014/01/23/wearables-to-create-personal-data-streams/?utm_campaign=January_2014_Newsletter.html&utm_medium=email&utm_source=Eloqua

Some Instructable wearable projects.

http://www.instructables.com/id/Despicable-Me-Minion-Costume-1/

http://learn.adafruit.com/light-activated-pixel-heart

New Zealand has a a strong wearable art movement.

http://www.nst.com.my/life-times/tech/top-picks-ground-breaking-wearable-gadgets-1.528292

http://realbusiness.co.uk/article/26128-7-of-the-best-tech-gadgets-from-londons-wearable-technology-show

http://www.pcadvisor.co.uk/news/google-android/3507296/android-wear-release-date-smartwatches/?cmpid=HTML-DN190314&olo=daily%20news

http://sensoree.com/

LDR, our first sensor

Some good code and information here.
Light dependent resistor circuit. See http://www.ladyada.net/learn/sensors/cds.html

Some voltage division images

We often want a sensor to send its signal using a changing voltage. For instance when the temperature is high we get a big voltage, and when the temperature is low we get a low voltage. Note that normally the input to an Arduino analog pin has to be between 0 and 5 volts.

Futurlec is a good site for buying Atmel ICs

Voltage division

Many sensors we use with the Arduino allow us to sense a changing signal, like light or heat, in terms of a changing voltage. We need to work out the approximate analog input value.

You have to identify all the parts of our Arduino

The Sparkfun Arduino Uno smd

Can you identify all the parts.