Burning COM ports (?) and buzzer problems

(Peter Norberg) #1

Hi everybody!
I need some help with two issues I’m having:

  1. I seem to have trouble communicating with my pro micros through the COM port after on no less than three different boards. The funny thing is, they all (at least two of them) stopped responding in the Arduino IDE after I uploaded Arduventure. First time I did it through a hex uploader, the other time through a normal sketch upload. I think it really sounds silly, but that’s the only common factor I can think of. Nothing happens in the device manager also. The game works however in my custom arduboy, What have I done?

  2. I have two buzzers - one analogue and one digital. When I started I thought the both looked the same and connected the digital one (I now know). No resistors or anything just pin 5 and gnd. The sound was bad but kind of acceptable but then I found out that I was using the wrong one and switched to the analogue. Much better audio.After fiddling around with the build, adding a LIPO and charger, the speaker became worse and worse to the point where they both sound horrible. I googled and came up with conflicting answers to if a resistor is needed or not, or if you could break the buzzer or the actual board pin. The piezo buzzers seen very standard: https://goo.gl/images/C2Ncfz

I have this problem on both of the above boards. I switched to my UNO and both buzzers seem fine from a standard test sketch.

Hope you can help! Cheers!

EDIT: I found “Upload Game” in the Arduventure menu and I came to new insights. If I hold down, plug in the USB, upload sketch and then release when it goes from compiling to upload. I then found similar threads about it. Strange that a sketch can change a bootloader like that, no?

(Pharap) #2

Are you using the pro-micros in Arduboy clones or are they unrelated to your Arduboy?
What exactly is your setup?
Have you looked at the device manager to check whether your ports have changed?

(Peter Norberg) #3

Hey! The problem with my COM is in the past (as wrote in my Edit) but I haven’t figured out the problem with my declining audio from the buzzer. It’s just a small vibrating sound now.


sounds like the io pin is damaged because you overloaded it.

A speaker has a very low resistance (4-8 ohm) and can’t be driven by an io pin directly unless you limit the current considerably using an series resistor and a capacitor to block dc current (when no sound is playing)

(Peter Norberg) #5

Yeah I figured. I think it’s strange though there are barely any mention of this in the tutorials I have been following. I guess most people that are into this kind of development are much more experienced in electronics than I am so the can figure it out themselves. I learn as I go.

So, what’s the preferred pinout? Pin to + on buzzer, - on buzzer to resistor to ground? What resistance? Or where does the capacitor come into play? Thanks!


I didn’t really look around for toutorials. But the schematic uses a capacitor in series (which is an actual resistor in hardware).

I think you’re unlucky getting the wrong buzzer. There are two kinds of ‘buzzers’ active and passive ones. Because your’s has a + symbol I think you’ve got an active one.

  • An active buzzer has some electronics inside to produce sound when power is applied.
  • A passive buzzer is just a piezo speaker that requires an alternating current (the sound) to produce a sound.

You can get away by hooking a passive piezo speaker directly to I/O pins because it has a high impedance (high resistance). However it is recomended to still put a resistor in series to limit current at high frequencies and noise.

However when using an ordinary (loud)speaker you can’t hook it directly to I/O pins as it has a very low impedance (low resistance) and when the pin is as a fixed high state a constant current will flow continiously through the speaker which is basically the same as shorting the I/O pins. A simple way hook up a (loud)speaker is to put a 100nF (0.1 micro Farad ) capacitor in series with the speaker. It is also recomended to put a resistor in series to limit current at high frequencies and noise.

Hooking up a Loudspeaker this way will produce a much lower volume though as they require more power to produce sound. They are usually driven by a transistor or an amplifier.

To get back on your sound problem. If you only hooked up your speakers to pin 5 and ground (GND). You might still be able to get better sound out of it when you connect the other end of the speaker to 5V instead of GND (but use a resistor and capacitor with your ‘analog’ speaker)