Re: [Fwd: Re: [avr-chat] New Programmer, Small Program, F_CPU for Atmega644]

[Robert L Cochran]

John Rehwinkel wrote:
>> I simply couldn't get avrdude to
>> "find" the device named usbtiny on my Fedora 7 (linux) box. (I built a
>> USBTinyISP programmer, produced as a kit by Limor Fried.) It doesn't
>> work when I m an ordinary user. I think that is significant because
>> running `lsusb` as a user will not show me any output, but running
>> `lsusb` as root will.
>
> That's your clue. It's a permissions problem. Probably the USB node
> in /dev is owned by root and not read/write by other users. There's
> probably a way to configure the driver to create nodes usable by
> everybody.
>
>> Well, I had gotten my feet wet with the code, and I suppose that is a
>> good thing. I have a feeling there are not too many people who use
>> avrdude on Fedora 7 and it hasn't had an extended amount of testing as a
>> result.
>
> That may be the case. I use it on MacOS, which is a BSD variant, an
> entirely different code tree than the various Linuxes.
>
>> Bob Cochran
>> Greenbelt, Maryland, USA
>
> Heh, I'm local to you (northern VA)!
>
> -- John
>
>
>
Hi John,

I'm glad we are local to each other. Maybe we can meet some time.

Preston suggested I try the usbtiny programmer on Windows XP and it
turns out it at least initializes the target device normally. Here is
the sequence of my actions:

1. I booted to XP and logged into my user account (which has
administrative privileges...)
2. I plugged the usbtinyisp programmer into an powered USB hub. The
programmer in turn is connected to an AtMega644 circuit on a breadboard.
The breadboard circuit isn't powered on yet.
3. The green LED goes on to my great pleasure!
4. In a command prompt I issued

`avrdude -c usbtiny -p m644'

5. avrdude is able to talk to the programmer, but not the Mega644 since
that circuit isn't powered on.
6. I connect power to the ATMega644 circuit.
7. issuing

`avrdude -c usbtiny -p m644'

now results in avrdude saying it can't find the usbtiny device.

8. I disconnect the usb cable from the usbtiny device, and connect it
back in again.

9. issuing

`avrdude -c usbtiny -p m644'

now results in avrdude connecting to the ATMega644 and reporting that
initialization succeeded and the fuses are okay. That is, it suddenly
works fine.

I'm using a 6 foot long USB cable.

I am using the 'AVR breakout board' (SKU BOB-08508 from Sparkfun
Electronics on http://www.sparkfun.com/ ) so that I can connect a 10-pin
IDC connector to it and plug this directly into my breadboard with the
ATMega644 circuit. I have the breakout board connected to the power and
ground on the breadboard.

Breakout Board's Reset pin is connected to pin 9 of the Atmega644
Breakout Board's MISO pin is connected to pin 7 of the Atmega644
Breakout Board's SCK pin is connected to pin 8 of the Atmega644
Breakout Board's MOSI pin is connected to pin 6 of the Atmega644

Pins 10-11 on the AtMega644 are connected to VCC and ground. Each pin
has one leg of an 0.1uF ceramic capacitor (marked "104Z") installed on
it to smooth out the VCC.

Pins 30-31 are connected to VCC and ground, the same as above, complete
with ceramic capacitor.

Pin 4 (PB3) is connected to an LED which is connected to a 150 Ohm resistor.

All other ATMega644 pins are left floating.

I wish I could test the usbtinyisp programmer for soldering defects of
my own making...I'm not sure why avrdude can't find the programmer after
I connect power to the Mega644 circuit. But it does find the Mega644
once I unplug and replug the USB cable.

Now to continue testing this in Linux! I really want to do AVR
development from a Linux account and I plan to submit a "Bugzilla" bug
to the Redhat people because avrdude as installed doesn't seem to work
for unprivileged users. Also, I think the USBTinyISP device can stand a
little more testing as a circuit. The reason for wanting Linux to work
doesn't really have noble open source roots...I just don't want to have
to set up the laptop again and again each time I want to test something.

Kindest Regards

Bob Cochran



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