SparkFun Forums

[skatefriday]

I have three problems with this programmer.

1) With the programmer connected to the breadboard, it holds the avr in reset. e.g. On my reset line before the resistor I have 5V after the 10k resistor I have 0v. This tells me that something is drawing the reset pin low. The there's no switch on my reset line, so it must be the programmer.

2) When the switch on the programmer is in the no power position, the programmer is still sending power to the board. e.g. My power indicator led lights up as do some of the pins on the avr (although not in the way the software i've programmed on the avr should tell them to light.) I expect the board to be dead when the no power switch is on.

3) The programmer seems to leave the avr in a state where it will only work imediately after being programmed. e.g. Cut the power, disconnect the programmer and turn power on again and the avr is dead, even though I've check Vcc and AVcc going into the avr as well as the reset line. Plug the programmer back in, reprogram and the avr software runs and my board performs as expected. Cut the power and turn power back on and the board is dead again.

[skatefriday]

Here's a photo of my board.



Ignore the bottom half of the board. It's disconnected entirely
from the top half of the board.

A closeup of the programmer connection. Note that the programmer, out of
the frame of this picture is in the "no power" switched position and yet, note
that the green led, indicating power is lit. A multimeter probe shows a little
less than 3.5V on the power rail.



Sorry I couldn't get a close enough photo with enough light to show the
individual connections into the 10 pin connector. I've checked them many, many
times and they are correct. The board does program as outlined below.

If I turn the board power switch on and program the board with

avrdude -c usbtiny -pm328p -U flash:w:blink.hex

The programmer works and the red led on PORTD blinks.

If I then pull the usb cable out of the programmer, turn the board off and
back on again, then the reset line is 0V. Sorry I couldn't take a picture
and hold my multimeter probes at the same time (don't have alligator clips,
must buy some).

In the following photo, the programmer is disconnected, the board power is
on and I read 0V on the reset line at pin 0. If I take a reading on the other
side of the 10K resistor I see 5V. The AVR is not running it's software. Presumably
because something is pulling the reset pin low.



If I turn off board power, disconnect the 10pin programmer cable then turn board power
on then the reset pin reads 5V, but the AVR still doesn't run the software that was just
programmed.

In summary:

- Board power on, program avr, avr immediately runs software
- Disconnect usb cable from programmer, power cycle board
nothing runs, reset pin 0V.
- Disconnect usb cable and 10pin connector, power cycle board,
nothing runs, reset pin 5V.

Any clues as to where to go from here? Any hints on how to debug
what's going wrong?

Any comment on whether the pocket programmer is broken given that
I have it switched to no power and it's pushing 3.5V out to the board?

Thanks in advance.

[skatefriday]

To followup with the defective programmer thread, I connected
a test lead to Vcc on the 10 pin connector and another to one of
the ground pins.

With the switch on the programmer in the "no power position" I
read 4.3V on the multimeter. That 4.3 was bouncing around like
crazy as well. See picture.



With the switch on the programmer in the "power target" position I
read a steadier 5V on the Vcc pin on the connector. e.g.



I looked at the schematic for the programmer and I don't think there's
any way that this should be the case unless the programmer is defective.

Am I right or am I missing something?

[skatefriday]

Also note that with the "power target" switch selected the programmer
will not program the AVR.


avrdude -c usbtiny -pm328p -U flash:w:blink.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x1e950f
avrdude: NOTE: FLASH memory has been specified, an erase cycle will be performed

To disable this feature, specify the -D option.
avrdude: erasing chip

avrdude done. Thank you.

Instead of the other two lines of Writing #####.... and Reading ##### ....
The above is all I get.

This is why I was using the "no power" selection to begin with.

[boris_1981]

Hey there.

Dont disconnect the cable from the computer. Disconnect the cables from the breadboard. Check if that helps.