JTAG Joint Test Action Group Standard Test Access Port - PowerPoint PPT Presentation

P ROGRAMMING AVR ON B READ B OARD Jatinder Singh Chhabra(200601120) Digvijay Singh (200601128)

P ROGRAMMING AVR ON B READBOARD  Programmer Circuit  Circuit which is used to program a micro controller  There are various techniques in practice and all of them have their own advantages and disadvantages

I NDEX  LVP – Low Voltage Programming  HVSP – High Voltage System Programming  JTAG – Joint Test Action Group

L OW V OLTAGE P ROGRAMMING  Also called - In System Programming  Program micro-controller on chip along with all peripheral devices  Via SPI at working voltage of 2.7-6 V  Needs VCC, GND, RESET and 3pin for SPI

L OW V OLTAGE P ROGRAMMING  Advantages:  Less chance of accidental damage  No need for separate power supply  Dis-advantages:  If fuse bits like reset when disabled than LVP cannot be done

L OW V OLTAGE P ROGRAMMING  Note:  Accidentally fuse bits changed and than high voltage programming is needed

JTAG  Joint Test Action Group  Standard Test Access Port  Boundary-Scan Architecture  method for testing interconnection (wire lines) on printed circuit boards  Used as an IC debug or probing port  JTAGEN Fuse needs to be enabled

JTAG  Break and step in functions for extensive on-chip debugging

H IGH V OLTAGE P ROGRAMMING  12V is applied to the RESET pin  All AVR devices can be programmed  The device is taken out of the system

H IGH V OLTAGE P ROGRAMMING  Advantages  Work even if fuse bits are set  Some devices can only be programmed using HVSP  Disadvantages  Need two different power supplies  12V can damage if there is current leakage  Need to remove all peripheral devices

C OMPUTER I NTERFACE  USB  Serial Port(RS232)  Parallel Port

S ERIAL  Can be connected to SPI or USART  High Voltage circuit is complex and shown only for completeness

S ERIAL L OW V OLTAGE P ROGRAMMING C IRCUIT http://electrons.psychogenic.com/modules/arms/art/5/AVRInSystemProgrammer.php

S ERIAL L OW V OLTAGE P ROGRAMMING C IRCUIT

http://www.scienceprog.com/avr-serial-and-parallel-high-voltage-programmer/

DAPA  Programming done through SPI  Parallel port is easily available on most of Systems  Pros and cons  Very simple circuit and cheap implementation  Keep parallel port cable short because clock is also transmitted(SPI)  Command to check if circuit is ready  # uisp -dprog=dapa  Output : - Atmel AVR ATmega32 is found.  100 Ω resisters are used to protect uC from voltage spikes

DAPA C IRCUIT http://www.captain.at/electronics/atmel-programmer/

USB P ROGRAMMER  Latest Generation of Programming Circuits.  Support for Universal Serial Bus (USB).  Programming done through SPI interface.

USB P ROGRAMMER http://www.ladyada.net/make/usbtinyisp/parts.html

USART  Programming possible with Boot loader  Fuse bits cannot be changed  Useful for program upgrades

USART P ROGRAMMERS  Some Programmers come bundled with microcontrollers which have bootloader installed on them.  Their Programming circuit could be made extremely simple.  Example is a microcontroller with USART bootloader preinstalled can be programmed with 4 wires Vcc, gnd, Tx, Rx.  Negative point here will be that bundling software on pc will also have to be constructed as default programming softwares like avrdude or uisp may not understand the underlying protocol.

S OFTWARE  With all the above circuit one requires a software on computer.  Linux  Uisp  avr-gcc  Windows  Avr-studio  ponyprog

N OTE  Accidental changing fuse bits  Need to take care fuse bits get changed by mistake  Voltage Spike protection  High Baud rate need Crystal oscillators  Do not push an IC forcefully into the breadboard

R EFERENCES  http://www.lancos.com/prog.html  http://electrons.psychogenic.com/modules/arms/art/ 5/AVRInSystemProgrammer.php  http://www.scienceprog.com/avr-serial-and-parallel- high-voltage-programmer/  http://support.atmel.no/bin/customer?=&action=vie wKbEntry&id=343  http://www.captain.at/electronics/atmel- programmer/