/ATtiny

TinyAVR/ATtiny

Primary LanguageCBSD 3-Clause "New" or "Revised" LicenseBSD-3-Clause

TinyAVR/ATtiny

Information of this README and comments in this project may be incorrect. This project is not an official document of Microchip Technology Inc., Atmel Corporation, and other holders of any Intellectual Property (IP).

Purpose

  • To Develop Software of TinyAVR/ATtiny Using C Language and Assembler Language

About TinyAVR/ATtiny

  • TinyAVR/ATtiny is a family of microcontrollers. I'm trying to make applications of ATtiny13/85 which has 8 pins.

  • ATtiny13 is the simplest one. Available interfaces are PWM, ADC, GPIO, and Comparator. It also has a 8-bit timer/counter, and has a unique 9.6MHz RC oscillator which allows to make a software UART Tx with the baud rate 9600, 19200, 38400, etc.

  • ATtiny85 can make a pair of software UART Tx and Rx with full duplex. In applications with real time processing, I'm trying serial communication with ATtiny85 on low baud rate like 1200, considering to implement the RS-485 interface for a unidirectional networking with a wide range such as illumination.

Installation

  • Install packages to Raspbian Buster on Raspberry Pi.
# Do as Superuser, Install Git and Make
sudo apt-get update
sudo apt-get install git
sudo apt-get install make
# AVR Programmer
sudo apt-get install avrdude
sudo apt-get install avrdude-doc
# Binary Utilities including GNU Assmebler
sudo apt-get install binutils-avr
# Assembler Compatible with AVRASM32
sudo apt-get install avra
# Compiler and C Library
sudo apt-get install gcc-avr
sudo apt-get install avr-libc
  • Open /etc/avrdude.conf to enable programming with GPIOs.
sudo nano /etc/avrdude.conf
  • Uncomment and modify "linuxgpio" lines as follows. In this case, GPIO22 for RESET of TinyAVR/ATtiny, GPIO23 for SCK, GPIO24 for MOSI, and GPIO25 for MISO.
programmer
  id    = "linuxgpio";
  desc  = "Use the Linux sysfs interface to bitbang GPIO lines";
  type  = "linuxgpio";
  reset = 22;
  sck   = 23;
  mosi  = 24;
  miso  = 25;
;

  • Connect Raspberry Pi and TinyAVR/ATtiny through assigned GPIOs. When connecting assigned GPIOs and TinyAVR/ATtiny pins to program, use appropriate resisters to limit electric current for hardware's safety. DON'T INPUT VOLTAGE OVER 3.3V TO GPIO PIN! OTHERWISE, YOU WILL BE IN DANGER!

  • Connect 3.3V Power of Raspberry Pi to VCC of TinyAVR/ATtiny, GND of Raspberry Pi to GND of TinyAVR/ATtiny. NEVER USE 5.0V POWER.

  • Clone this project using Git, and compile the code then program the binary to TinyAVR/ATtiny.

cd ~/Desktop
git clone https://github.com/JimmyKenMerchant/ATtiny.git
# Enter Directory
cd ATtiny/13/blinker
# Compile
make
# Program Binary to TinyAVR/ATtiny
make install
  • Place programmed TinyAVR/ATtiny to your circuit.

Memos on Development

  • ATtiny13 has 64 bytes SRAM which enables stack (pop/push) operations. Caution that SRAM is shared by global variables and stack. Many stack operations may cause memory overflow and corrupt global variables. Arrays of constants can be stored in program space using PROGMEM attribute with <avr/pgmspace.h> library.

Sequencer, A Music Box

  • Sequencer is a music box. Note that Sequencer GPIO or Sequencer Pulse-width which are aiming to light decorations mainly (Sequencer Pulse-width can be modified as a Voice Box through changing to high sampling rate, even though it needs more SRAM and program space just like in ATmega).

  • Sequencer has alternative versions such as "main.c.jinglebells".

cd ATtiny/13/sequencer
# Change Original Version to Alternative Version
mv main.c main.c.origin
cp main.c.jinglebells main.c
# Check Difference between Original Version and Alternative Version
git diff main.c
  • Sequencer emits 180 degrees phase shifted saw tooth wave; because in the ideal behavior, the wave can be transformed to sine wave through omitting all harmonics. Making square wave is easy; however in my experience, it often has noise like resonance after rising or falling edge, causing losses of electric power. Square/pulse wave can be made by a comparator inputted saw tooth wave.

RS-485 with ATtiny85

  • In a unidirectional networking, connections can be layered using sequencers that transmit bytes with serial signals. In addition, relaying can be structured using RS-485 transceivers.

  • The software UART tolerates the error of baud rate up to 3.75%. On the fixed temperature, the internal RC oscillator of ATtiny85 keeps the clock accuracy within +-1% change according to the page 164 of the datasheet of ATtiny25/45/85 (Rev.:2586Q-AVR-08/2013). However, the RC oscillator is affected by temperature, causing a possible error on transmission, but this issue can be resolved as long as each 1 byte serial signal from the host have equal interval. In the case that the host sends 1 byte serial signal at 60Hz, ATtiny85 can know the accuracy of its internal RC oscillator; i.e., when ATtiny85 gets 60 bytes (1 seconds) from the host, it compares the counting number of 9600Hz internal timer (the actual frequency would be approx. 9615.38Hz) with the number of 9600 to adjust the value of OSCCAL.

Electric Schematics

Technical Notes

December 1, 2019

  • cat /proc/cpuinfo | grep 'Model': Raspberry Pi 3 Model B Rev 1.2
  • lsb_release -a | grep 'Description': Raspbian GNU/Linux 10 (buster)
  • git --version: git version 2.20.1
  • make --version: GNU Make 4.2.1 Built for arm-unknown-linux-gnueabihf
  • avr-gcc --version: avr-gcc (GCC) 5.4.0
  • avr-as --version: GNU assembler (GNU Binutils) 2.26.20160125
  • avra --version: AVRA: advanced AVR macro assembler Version 1.3.0 Build 1 (8 May 2010)
  • avrdude -v: Version 6.3-20171130
  • apt-cache show avr-libc | grep 'Version': 1:2.0.0+Atmel3.6.1-2
  • Description: Take these commands at the terminal of Raspbian I use for this project.

Links of References