Turned arduino 5vdc analog pin to 0vdc (gnd) in order to mimic a momentary switch

arduino

I'm just wondering how I would go about getting the normal 5vdc that comes out of the Arduino analog/digital pins to a 0vdc signal? I wanting to mimic a push button (momentary switch) so that it acts as if I am pushing a button on a remote.

I'm sure I could use a resister of some value in order to get it down to 0vdc but I am unsure of that value nor am I sure that's the best way to go about doing something like this.

Any help would be great! Thanks!

update

Would using a TLP592A work doing it this way:

enter image description here

Best Answer

What interface you will need depends on the circuit of the remote. If the switch shares a common ground with the Arduino then you might get away with just connecting directly to it. However for safety I would use a diode or transistor to provide an 'open collector' output. The circuit below shows how both a diode and transistor would be wired (choose one or the other, not both!).

enter image description here

Some remotes have their switches connected to battery positive, perhaps to make the transmitter turn on whenever a button is pressed. Others have buttons arranged in a matrix of rows and columns, so both ends of the switch may be floating. In these cases you can use an opto-coupler or PhotoMOS 'relay' (opto-coupler with FET output).

The circuit below shows how to use an opto-coupler. Note that the opto-coupler's output is polarity conscious, so you may have to swap pins 4 and 5 to get it working.

enter image description here

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Electronic – arduino – digitalRead sampling rate for Arduino Uno

You have two problems right now that are separate from each other.

1) Button bounce

2) Improper button wiring

First, you need to introduce a delay into your interrupt function so that it won't keep registering each rise and fall of the bounce as a separate button press. Use "delayMicroseconds()" because apparently you can't use regular "delay()" inside interrupts. Id suggest a 20,000 microsecond delay.

Second, you need to put a pull down resistor onto the digital pin that you are sampling.

The problem you are having is that the pin is in input mode and thus at high impedance (very high resistance) and thus has a tenancy to "float". If you put a voltage to it, it charges up like a capacitor and since the pin itself has very high resistance to ground, it takes a while for the charge to dissipate to the point where the Arduino will register a LOW again. A 10k resistor from the pin to ground will force the "capacitor" to discharge quickly after current from the button has stopped flowing.

Finally, the Arduino is pretty quick at it's read/write operations (I'm a mechanical engineer, ALL electronics happen "quickly" in comparison to mechanical systems, so it's relative I guess). Here's a link to some test results.

TL;DR verson:

What these values tell me, is that we can do about:

10 analog 10-bit readings per millisecond with analogRead()
128 pwm settings per millisecond with analogWrite()
220 pin reads per millisecond with digitalRead()
224 pin writes per millisecond with digitalWrite()
1056 pin reads per millisecond with direct port reads
1059 pin writes per millisecond with direct port writes

Electronic – arduino – Intentionally mis-use the USB port on an Arduino

So the usb port is being as a general connector, not as a USB standard device? If so, just get a usb port or cable and wire it to the Arduino outputs.

If it's being used as an actual usb slave device, then that's alot more complicated.

Either way, if you want to use the existing usb port, you would need an arduino that uses a AVR ic as the usb port, and reprogram it so that it can do two functions (not simple). The older arduinos use a FTDI FT232R, a dedicated usb to serial IC that would not work well with what you want to do.

Best Answer

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Electronic – arduino – digitalRead sampling rate for Arduino Uno

Electronic – arduino – Intentionally mis-use the USB port on an Arduino

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