Fab Academy | Jasmin Cheng

Week 07 : A Beginner's Guide to Electronics Programming

Assignment

Read a microcontroller data sheet, program your board to do something, with as many different programming languages and programming environments as possible.

My Goals

Write a program in Arduino IDE for the Hello Echo Modified board

What I Learned

How to read the ATtiny44 datasheet
How to break a 6-pin FTDI header
How to use the Arduino Reference Library
How to mash-up code to make it do cool stuff

Tooling, Materials & Speeds

Arduino IDE

Downloads

Program that gets the LED on the Hello Echo board blinking, until you press the button, which makes it fade (Arduino IDE)

Documentation

This week’s assignment was to program my modified Hello Echo Circuit board and Fab ISP by getting the button to interact with the LED. I had to spend several weeks on this assignment because I had to create a second ISP (could not program the first one, could not figure out what was wrong with it - see Week 4), and also redesign my version of the Hello Echo board (I mis-placed the 6-pin header).

Before getting too deep into it, I wanted to share an analogy that Craig used to help me wrap my head around electronics design.

First Layer = physical
Second Layer - functional groups
Firmware = setting non-specific inputs and outputs that can be specialized for what you want to do
Each layer of cake has a number, depending on which layer you’re working on

For this week's assignment, we will be working on the upper layers of the cake. It assumes that the physical layers have been assembled, the physical components know what they're going to be used for and now we're writing instructions to tell those components what to do.

I followed Anna's tutorial on programming with the Arduino IDE and downloaded the Arduino IDE software for my Macbook and the ATTINY zip files. I was able to get the ATTINY hardware files to show up in the Arduino IDE.

NOTE: The ATTINY library doesn’t work with newer versions of Arduino. The version that worked for me was v.0.1.03

Are both the board and ISP connected to power?

This was a funny rookie mistake I made. I thought I only needed to power the board, and that the ISP would magically get power from the board. This is obviously not true.

Following the tutorial, I tried to “Burn Bootloader” and received this message:
avrdude: stk500v2_command(): command failed
avrdude: stk500v2_program_enable(): bad AVRISPmkII connection status: Unknown status 0x00
avrdude: initialization failed, rc=-1
Double check connections and try again, or use -F to override this check.

All the ways you can test the Hello Echo board

Re-tested the connections using the multi-meter (looking for voltage, everything that should be connected is connected, everything that shouldn’t be connected isn’t connected)
Used a USB2 converter
Put a piece of paper under the 6-pin header to prevent shorts (because mine was bent in order to sit in the middle of the board)
Tried my board on another computer
Tried 2 other working boards - they burned boot loader OK, which means the AVR ISP was working (*remember to use 2nd Serial Port)
Tried to burn the working boards with my computer, and they burned boot loader OK, which means the environment was working

Board 2

I decided to build a new Hello Echo board from scratch. And then I broke it because I didn't know to put hot glue on the sides of the 6 pin header to reinforce it. (_ _)

Milling and stuffing the board the second time took less than an hour. That was nice.

This time, I went through all the previous testing steps to make sure my board was electronically sound before I plugged it in. When I did, I was able to burn bootloader, so I started programming.

The first step to take when programming a board is to read the data sheet of the microcontroller, in this case the ATTiny44, and look at the pinout diagram. This tells you what number pin the LED is attached to, which you would need to declare in the code in ARduino IDE.

Craig gave me a challenge to program the board to blink continuously, and when I push the button, the light would fade. I used the Arduino Reference Library to find example code for controlling the button, to get the LED to blink and to get the LED to fade.