Exercise 08 Embedded Programming


Requirement

Datasheet of Atmel Microcontroller

The microcontroller we are working to on is a Atmel ATtiny44A MCU. The difference between a ATtiny44 and a ATtiny44A is that the latter is an optimized version of the former. The ATtiny44A is a functionally identical, drop-in replacement for the ATtiny44. They are subject to the same qualification process and same set of production tests, but as the manufacturing process is not the same, some electrical characteristics differ.
To locate the datasheet of an MCU, go to the Atmel website >> Atmel AVR 8-bit and 32-bit Microcontrollers >> tinyAVR MCUs >> ATtiny44A

Pin Configurations of ATtiny24A/44A/84A

Words like PDIP/SOIC/QFN/MLF/VQFN really buffet me, and I came across a helpful article which explains these confusing acronyms.

Characteristics of the ATtiny44A:

Programming of Microcontroller

To upload a program to a microcontroller (MCU) chip, an ISP programmer is required. In-system programming (ISP), also called In-Circuit Serial Programming (ICSP), is the ability of some programmable logic devices, microcontrollers, and other embedded devices to be programmed while installed in a complete system, rather than requiring the chip to be programmed prior to installing it into the system. I have decided to buy an Arduino Uno, which cost me $21. This will be as a ISP to programme my Hello board, which I milled and stuffed in week 6. The board uses an ATtiny44A AVR chip microcontroller. AVR is a modified Harvard architecture 8-bit RISC single-chip microcontroller, which was developed by Atmel in 1996. The AVR was one of the first microcontroller families to use on-chip flash memory for program storage, as opposed to one-time programmable ROM, EPROM, or EEPROM used by other microcontrollers at that time.

Using an Arduino as an AVR ISP

There is an example sketch in Arduino IDE called ‘ArduinoISP.’ Uploading this code to the Arduino will basically make the Ardunino act as an AVR programmer. This isn’t really recommended for production of boards, or boards with lots of memory.

Connecting the Hello board to an Arduino ISP

Installing a Bootloader

The bootloader is basically a .hex file that runs when you turn on the board. It is very similar to the BIOS that runs on your PC. It does two things. First, it looks around to see if the computer is trying to program it. If it is, it grabs the program from the computer and uploads it into the ICs memory (in a specific location so as not to overwrite the bootloader). That is why when you try to upload code, the Arduino IDE resets the chip. This basically turns the IC off and back on again so the bootloader can start running again. If the computer isn’t trying to upload code, it tells the chip to run the code that’s already stored in memory. Once it locates and runs your program, the Arduino continuously loops through the program and does so as long as the board has power.

Arduino IDE settings for programming the hello board

Programming the Hello board

File >> Preference >> Check on show verbose output.

If all goes well, you should see something like this:

   
Sketch uses 1,094 bytes (26%) of program storage space. Maximum is 4,096 bytes.
Global variables use 9 bytes of dynamic memory.
C:\Program Files (x86)\Arduino\hardware\tools\avr/bin/avrdude -CC:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf -v -pattiny44 -cstk500v1 -PCOM4 -b19200 -Uflash:w:C:\Users\YORUIC~1\AppData\Local\Temp\build3a1d06f32e72991acd30501dda9c5795.tmp/Blink.ino.hex:i 

avrdude: Version 6.0.1, compiled on Apr 15 2015 at 19:59:58
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2009 Joerg Wunsch

         System wide configuration file is "C:\Program Files (x86)\Arduino\hardware\tools\avr/etc/avrdude.conf"

         Using Port                    : COM4
         Using Programmer              : stk500v1
         Overriding Baud Rate          : 19200
         AVR Part                      : ATtiny44
         Chip Erase delay              : 4500 us
         PAGEL                         : P00
         BS2                           : P00
         RESET disposition             : possible i/o
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65     6     4    0 no        256    4      0  4000  4500 0xff 0xff
           flash         65     6    32    0 yes      4096   64     64  4500  4500 0xff 0xff
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00
           lock           0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
           lfuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  9000  9000 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00

         Programmer Type : STK500
         Description     : Atmel STK500 Version 1.x firmware
         Hardware Version: 2
         Firmware Version: 1.18
         Topcard         : Unknown
         Vtarget         : 0.0 V
         Varef           : 0.0 V
         Oscillator      : Off
         SCK period      : 0.1 us

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.05s

avrdude: Device signature = 0x1e9207
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "C:\Users\YORUIC~1\AppData\Local\Temp\build3a1d06f32e72991acd30501dda9c5795.tmp/Blink.ino.hex"
avrdude: writing flash (1094 bytes):

Writing | ################################################## | 100% 1.91s

avrdude: 1094 bytes of flash written
avrdude: verifying flash memory against C:\Users\YORUIC~1\AppData\Local\Temp\build3a1d06f32e72991acd30501dda9c5795.tmp/Blink.ino.hex:
avrdude: load data flash data from input file C:\Users\YORUIC~1\AppData\Local\Temp\build3a1d06f32e72991acd30501dda9c5795.tmp/Blink.ino.hex:
avrdude: input file C:\Users\YORUIC~1\AppData\Local\Temp\build3a1d06f32e72991acd30501dda9c5795.tmp/Blink.ino.hex contains 1094 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 1.25s

avrdude: verifying ...
avrdude: 1094 bytes of flash verified

avrdude done.  Thank you.

Modifying the codes of example sketches

Blink at 1 second interval

  digitalWrite(7, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);              // wait for a second
  digitalWrite(7, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);

Blink Faster at 0.1 second interval

  digitalWrite(7, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(100);              // wait for a second
  digitalWrite(7, LOW);    // turn the LED off by making the voltage LOW
  delay(100);

LED turns on only when button is pressed

  if (buttonState == HIGH) {
    // turn LED on:
    digitalWrite(ledPin, LOW);
  } else {
    // turn LED off:
    digitalWrite(ledPin, HIGH);
Toggle LED on and off when a button is pressed 

  val = digitalRead(BUTTON);  // read input value and store it

  // check if the input is HIGH (button pressed)
  // and change the state

  if ((val == HIGH) && (val != old_val)) { // differeniate the exact moment when 
                                           // the button is pressed.
    state = 1 - state;
    delay(10);
  }

  old_val = val; // val is now old

  if (state == 1) {
    digitalWrite(LED, HIGH);
  } else {
    digitalWrite(LED, LOW);

Connecting the Hello board to FTDI USB to TTL Serial Converter

A serial bus consists of just two wires - one for sending data and another for receiving. As such, serial devices should have two serial pins: the receiver, RX, and the transmitter, TX. It’s important to note that those RX and TX labels are with respect to the device itself. So the RX from one device should go to the TX of the other, and vice-versa. The transmitter should be talking to the receiver, not to another transmitter.

Physical connection between the Arduino, Hello board and the FTDI USB To TTL Serial Converter


Display the state of LED on putty terminal via FTDI USB To TTL Serial Converter 
  if(mySerial.available() > 0){
    state = mySerial.read();
    flag=0;
  }
  // read the state of the pushbutton value:
  val = digitalRead(buttonPin);

  // check if the pushbutton is pressed.
  // if it is, the buttonState is HIGH:
  // resets written counter to 0
  if ((val == HIGH) && (old_val == LOW)) {
    state = 1 - state;
    flag = 0;
    delay(10);
  }
  old_val = val; 

  if ((state == 1) && (flag == 0)) {
    digitalWrite(ledPin, HIGH);   // turn the LED on (HIGH is the voltage level)
    mySerial.println("led is on!");
    flag = 1;
  } else if ((state == 0) && (flag == 0)) {
        digitalWrite(ledPin, LOW);
        mySerial.println("led is off!");
        flag = 1;
        }
    else {
      //do nothing
    }

Errors encountered

  avrdude: stk500_recv(): programmer is not responding
  
  avrdude: Yikes!  Invalid device signature.
         Double check connections and try again, or use -F to override
         this check.
  
  avrdude: ser_open(): can't set com-state for "\\.\COM4"
  
  avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.05s

avrdude: Device signature = 0x000000 (retrying)

Reading | ################################################## | 100% 0.05s

avrdude: Device signature = 0x00ffff
avrdude: Expected signature for ATtiny44 is 1E 92 07
         Double check chip, or use -F to override this check.

avrdude done.  Thank you.

Wrong microcontroller found.  Did you select the right board from the Tools > Board menu?

So far I've encountered with these error messages when I tried to upload the sketch to the board. I tried many ways to troubleshoot, such as exchanging the cables, testing the board with a multimeter for shorts, reflowing in case there's any cold joints, using a classmate's computer and arduino isp, etc and all didn't work. The solution was very odd because it was after I heated up the chip area on the board a little with a hot gun or a hairdryer, it was able to load the program! Somehow heating the board a little causes it to work. That really puzzles me!



Download Week 8 work files


References