Help understanding the AVR atmega8 used in this schematic

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Hi,

I'm a software guy that has found learning and playing with microcontrollers as a fun way to get introduced to hardware/electronics. I've finished a cool little robot with AVR now working on something else I wanted to learn interfacing USB.

I wana fallow the schematic pictured below but I'm having a hard time figuring out what AVR they are using. I have a few spare atmega8-16PU laying around I'd love to use but I can't tell if its the one being used on this schematic. They use a chip that uses 3.3V and can go 16MHz. The atmega8L can't got 16MHz, and the regular atmega8 are 4.5-5V so I'm a bit confused whats going on :P

Someone mind telling me whats the 16PU part stands for btw?

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By the way I didn't mention it but this is from http://www.obdev.at/products/avr...

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Quote:

Someone mind telling me whats the 16PU part stands for btw?

It should be there in the datasheet right at the very end where they tell you packaging and ordering information.

If you think education is expensive, try ignorance.

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emmannuel wrote:
Hi,

I'm a software guy that has found learning and playing with microcontrollers as a fun way to get introduced to hardware/electronics. I've finished a cool little robot with AVR now working on something else I wanted to learn interfacing USB.

If you're able to get USB interfacing working with the schematic you posted, you needn't bother with trying to locate a particular AVR. Just make your own out of sand, lighter fluid, and mayonnaise.

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Hmmm.... when I look at the link it says an ATTiny2313. Normally, the "P" suffix is reserved for the Picopower devices. And there is no Picopower version of the Mega8.

Dave

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dharper wrote:
Hmmm.... when I look at the link it says an ATTiny2313. Normally, the "P" suffix is reserved for the Picopower devices. And there is no Picopower version of the Mega8.

Dave

Only if it immediately follows the device name. After the dash it is part of the packaging, and temperature code. The P stands for the DIP (through hole) packaging. U us for industrial temperature range. The 16 means that it is a 16MHz part (thus implying 5 Volts)

Writing code is like having sex.... make one little mistake, and you're supporting it for life.

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emmannuel wrote:
Hi,

I'm a software guy that has found learning and playing with microcontrollers as a fun way to get introduced to hardware/electronics. I've finished a cool little robot with AVR now working on something else I wanted to learn interfacing USB.

I wana fallow the schematic pictured below but I'm having a hard time figuring out what AVR they are using. I have a few spare atmega8-16PU laying around I'd love to use but I can't tell if its the one being used on this schematic. They use a chip that uses 3.3V and can go 16MHz. The atmega8L can't got 16MHz, and the regular atmega8 are 4.5-5V so I'm a bit confused whats going on :P

Someone mind telling me whats the 16PU part stands for btw?

They are using a 16MHz/5V graded part (-16) Through hole package (P) and industiral temperature range (U)

The design is breaking the rules, as they are running the AVR at 3.3V at 16MHz this is beyond the specs for the AVR. Might work fine for a hobby project (then again, it might not work at all), but I would discourage it in a professional design.

Writing code is like having sex.... make one little mistake, and you're supporting it for life.

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Quote:
Only if it immediately follows the device name. After the dash it is part of the packaging, and temperature code. The P stands for the DIP (through hole) packaging. U us for industrial temperature range. The 16 means that it is a 16MHz part (thus implying 5 Volts)

Yep - I stand corrected.

Dave

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If you're able to get USB interfacing working with the schematic you posted, you needn't bother with trying to locate a particular AVR. Just make your own out of sand, lighter fluid, and mayonnaise.
LOL!

That may be a bit of an exageration, but I do agree that if you are interested in learning USB, it is probably easier start with a part with an actual USB interface.

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Thanks a lot of all your help. I'm looking around the other options and trying to figure out what would be the best avr chip to pic for this.

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I'd suggest asking on the AVRUSB forums but there seem to be examples for ATmega8, ATtiny2313 (I think) and I've implemented AVRUSB using an ATmega168 on an Arduino board with a "mini-shield" containing the USB related hardware.

Of bigger importance for AVRUSB is the clock frequency you use.

In general there's two AVRUSB circuits, one that powers the AVR at 3.3V (like the schematic you have) and the other that powers the AVR at 5V with diodes on the D+/D- lines to drop the data lines to around 3.3V.

--Phil.

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Thanks for your comments Phil. I sadly found their forums after I had already gotten these replies :P

One of the things I keep having issues with is figuring out whether a certain chip is programmable on the stk500 on the official docs I don't see anything mentioned on the mega168 and tiny2313. But it seems people use the stk500 for those so I think I'm ok.

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Quote:

on the official docs

"The" official doc on the STK500 and other tools is the Help subsystem of the latest AVRStudio.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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ive used the firmware only usb from the above site and it is excellent. ive tried attiny2313 and the atmega8. ive seen designs which use the attiny45 with an internal osc configured at 8mhz.

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The stk500 will program almost any Atmel AVR. The only problem is in the packaging. AFAIK the stk500 has DIP sockets.

If your AVR is an SMT device, you need to do things differently. Most people use the ISP interface for SMT designs. If you screw up and lock the AVR in an unrecoverable position, you're dead meat - discard that SMT AVR and put in a fresh one. The alternative is to use a connection jig to connect the SMT to the DIP socket.

If you think education is expensive, try ignorance.