Help! Newbie!

Development Boards MicroMod
1

I just got my first microcontroller, an ATmega8, for a school project. I also got the PG1B programmer and the P28 development board. I now have no idea what to do. For power, I’ve tried a couple of wall warts I have lying around that should have worked, but I’m not sure if they did or not. Anyway, I tried to put a program on there with PonyProg and Avrdude, but neither could recognize the chip. So, my questions are:

  1. The wall wart I used was rated at 12V but was actually giving off around 18V when I measured it. Could I have fried something? (I didn’t see any smoke)

  2. Does the indicator LED come on when power is applied to the board?

  3. What does the button do?

  4. If I am indeed getting power to the board, what could be the problem with the programmer?

Thanks a lot.

2

do you have a volt meter? If so, check the P28 board’s 5V regulator’s output (Vcc).

12V should be OK. You’ll see more like 18V from that wall-wart if it has no load current.

Try to use a 9V.

Look at the wall-wart transformer itself and see if it shows the voltage polarity on the plug. Match that to the schematic of your board.

As to the LED: Take a look at the schematic: it shows that if a jumper is installed, the LED is connected to a certain I/O pin on the microprocessor. So the LED can light only if the microprocessor outputs a “low” (0) to that pin.

With Vcc at 5v correctly, use your PC and programmer software. Try to read the chip’s ID. This will tell you if things are essentially working.

Button: Are you referring to the P28 board?

Of course, make sure that the chip is plugged in with pin 1 oriented correctly and no bent pins.

Also - the previous posts of, and the folks on the avrfreaks.net forum can help you too.

3

I have the same board, though I’m using an STK-500 for programming. The light on the board is not power indicator. It is tied to a pin on the microcontroller so it is under the control of whatever program in running on the microcontroller. Same with the button – it is tied to a microcontroller pin so you can use it as a simple input mechanism or trigger in your MC program.

The Seattle Robotics Society has a robot kit that includes an Atmega16 which is very similar to the Atmega8 you are using. There are 2 workshops with nice presentations and sample code all about the microcontroller and how to do things like flash leds, read pushbottons, use timers, drive motors, etc. All of the documents and sample code are a free download. Click on “Level 1” and “Level 2” in the menu to the left of the following page and look for links to the presentations and sample code in the body of those pages:

http://www.seattlerobotics.org/Workshop … kshops.php

4

I connected a 9V battery as a power supply, and I am getting around 2.6 V across the VCC and GND pins on the Atmega8. I think that either the voltage regulator is fried or the cpu is. Any suggestions?

5

Check that you are getting 8V or more out of the battery when it is connected to the board. If you are, you could try cutting the Vcc track where it leaves the regulator output capacitor, and see whether you get 5V out of it. If you are, there must be something shorting Vcc on the board. Regulators are quite tough and it is difficult to damage them.

Leon

6

I’m getting 9.4V out of the battery, and from the regulator I’m getting about 8.8V. It seems like either the regulator isn’t working properly or something else isn’t.

7

If the regulator is delivering 8.8V it must be faulty and you will almost certainly need to replace the MCU.

Leon

8

SmashedSqwurl:
I connected a 9V battery as a power supply, and I am getting around 2.6 V across the VCC and GND pins on the Atmega8. I think that either the voltage regulator is fried or the cpu is. Any suggestions?

I wonder why the Vcc for the ATmega8 is 2.6V whereas the regulator output is 8V? Measurement error? Broken PCB trace?