Fab Academy at AS220 Labs

August 5, 2010 2:34 PM

Complete and Working --> Modified Hello Echo + Button + FTDI v.2

by Anna Kaziunas France

Fab Academy Embedded Programming Assignment:

  1. add (at least) a button to the serial echo hello-world board
  2. modify the serial echo assembly program to respond to the button

I modified the hello serial echo board (my modified echo board version2 - see previous posts) to respond to a button and added an FTDI header so I could use it as a substitute for the internet 0 serial board. (I have a Mac and therefore no serial port).

The behavior is that the LED is always on - but when the button is pressed, it turns off.

Modified Hello Echo FTDI + Button

Shawn and I modified Elliot’s reprogramming the echo board code.

Here is the code:

; Modified.Hello.Echo.Blink LED.44.asm
;
; blink LED when button is pressed
;
; Code Created At FAB ACADEMY AS220 
; by Shawn Wallace & Elliot Clapp
; Last Modified 08/05/2010  - Anna Kaziunas France
;
; Permission granted for experimental and personal use;

.device attiny44
.org 0
cbi DDRA, 1
sbi DDRB, 2
loop:
    sbic PINA,1
    sbi PORTB, 2
    sbis PINA,1
    cbi PORTB, 2
rjmp loop

Here is How to Get the Board Running:

I use an usbtiny programmer.

Copy the above code into a text file and save it with YourFileName and .asm extension. Compile it using gavrasm:

gavrasm YourFileName.asm

Compiling the file will create a .hex file.

First - set the fuses on your board: 

avrdude -p t44 -c usbtiny -U lfuse:w:0x7E:m

Second - flash the attiny44 with the program code you just compiled: 

avrdude -p t44 -c usbtiny -U flash:w:YourFileName.hex

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