Question about chip programmers

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New here, pretty new to micro controllers too. Anyways, I had a question about programmers, like this one:

http://www.sparkfun.com/products/12

Like what is an in circuit emulator and how does this feature differ from other programmers?

And what is the ATJTAGICE interface?

Also what is the difference between the 2x5 pin connectors and the 2x3? The 2x5 just seems to have more grounds so whats the point in the big one?

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It only supports a few older type of AVRs. It will NEVER support modern AVRs.

I am sure that it will do an excellent job with a mega16, mega32, mega64, mega128 (and a couple of others). I use a similar device myself. (ETT USB-JTAG)

However, for the money that they are asking, I would buy a Dragon instead. (And pay extra for some cables and a case)

An 'in circuit emulator' allows you to single step programs on the real hardware, examine registers, memory etc.

It is far more useful than simply Simulating a program.

David.

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ltkenbo wrote:
And what is the ATJTAGICE interface?
JTAG, of course! Okay, to be less flippant, JTAG is a serial I/O interface designed for manufacturing and debug use. With the AVR, JTAG allows you access to the AVR's debug and programming resources.

ltkenbo wrote:
Also what is the difference between the 2x5 pin connectors and the 2x3? The 2x5 just seems to have more grounds so whats the point in the big one?
One is for JTAG and the other is for ISP (In System Programming). ISP is Yet Another Serial Protocol that allows access to the AVR's programming and debug resources.

Why two different programming mechanisms? Well, history and flexibility, really. Also, JTAG is boatloads faster than SPI. Between the two, I would choose JTAG over SPI, but there are reasons for going the other way.

As David said, the SparkFun interface just does not support the latest (or even somewhat older) AVRs. The Dragon he mentioned is the cheapest way to program and debug most AVRs. The exception AVR family for both of these is the XMega - for those processors, you need either an JTAGICE mkII or an AVR One.

Hope this helps!

Stu

Engineering seems to boil down to: Cheap. Fast. Good. Choose two. Sometimes choose only one.

Newbie? Be sure to read the thread Newbie? Start here!

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ltkenbo wrote:
Also what is the difference between the 2x5 pin connectors and the 2x3? The 2x5 just seems to have more grounds so whats the point in the big one?
There are two ISP header pinouts, one is the 2x3 and the other is 2x5. The 2x3 is the layout designed by Atmel, the 2x5 was designed by Kanda for their Atmel compatible development boards. Kanda designed the STK200 system. It is confusing that the AVR jtag connector is 2x5, but it is NOT compatible with the 2x5 ISP connector (that's why the Atmel JTAG comes with a "squid" connector with 10 loose flyleads). Most boards designed by Atmel will have the 2x3 ISP connector, third party boards might have the 2x5, or maybe both styles. The current Atmel ISP programmer has only the 2x3 connector, the older one could be equipped with both styles.
The JTAG programmer interface requires 4 wires (plus reset) to talk to the processor, ISP needs only 2 (plus the reset) while "debug wire" needs ONLY the reset line. The choice becomes important with low pinout devices!

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https://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=38691
has the Dragon in the programmers list for "METHOD 7: PDI".

"Dare to be naïve." - Buckminster Fuller

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gchapman wrote:
https://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=38691
has the Dragon in the programmers list for "METHOD 7: PDI".
Yes, but only a limited number of Xmegas are supported. And people here had great problems getting PDI to work with a Dragon.

Stealing Proteus doesn't make you an engineer.

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if your starting out with avr coding could I suggest getting an AVRdude programmer for $16