interfacing coin acceptor to raspberry pi
Re: interfacing coin acceptor to raspberry pi
Re: interfacing coin acceptor to raspberry pi
adafruit_support_rick wrote:What voltage level is the coin line pulsing at? You can use a level-shifter or a pair of resistors as a voltage divider to bring the coin line down to 3.3V.
As for splitting the coin line, you can simply connect it to both the vending machine and to the Pi through the level-shifter.
Re: interfacing coin acceptor to raspberry pi
dev64 wrote:How can I find out the voltage level for the con line?
Re: interfacing coin acceptor to raspberry pi
adafruit_support_rick wrote:dev64 wrote:How can I find out the voltage level for the con line?
An oscilloscope would be handy. I doubt that the pulses are long enough to give a good reading on a multimeter.
Where does the coin line go to? Some sort of microprocessor? Do you know what voltage that microprocessor runs at?
Re: interfacing coin acceptor to raspberry pi
Re: interfacing coin acceptor to raspberry pi
adafruit_support_rick wrote:Well, I think the coin line is open-drain, meaning that the voltage for the HIGH signal is whatever you pull it up to. So that's going to be set by the breathalyzer board. I doubt that the microprocessor on that board runs at 12V. If this is an older thing, it's probably running at 5V, so the coin line is probably running at 5V.
What you can try is to splice another wire into the coin line, and run it over to the PI. There, you want to make a resistive voltage divider.
To do that, you connect the coin line to a Pi GPIO pin through a resistor, then you connect another resistor from the same GPIO pin to ground. Like this:
The values for R1 and R2 depend on what the coin line voltage is. To be safe, you should probably first assume that Coin is 12V. In that case, you want the following values for the resistors:
R1: 56kOhm
R2: 22kOhm
Try that. If you can't see the Coin line changing on the Pi, then it's not running at 12V. You can try different resistors and assume Coin is 5V:
R1: 12K
R2: 22K
PLEASE NOTE: This is all at your own risk. We don't have good information on what kind of signal levels you're dealing with here. You run the risk of damaging your Pi, and we can't be responsible for that.
Re: interfacing coin acceptor to raspberry pi
dev64 wrote:What if the coin line was running at 5v, I could then simply power the pi with the coin line? I should probably determine what voltage is coming out of the coin line using a voltmeter. Can I power and read coin input from the coin line? that would be great! I also need some jumper cables for use with gpios.
dev64 wrote:On the other hand, this looks more promising and safer way to power the pi
http://www.ebay.com/itm/DC-Converter-St ... 1203074650
dev64 wrote:Is there a more elegant way to splice the coin line, i did rather buy a line splitter or a divider. I did rather not go down the path of resistors, the approach seems a bit too hackish.
Re: interfacing coin acceptor to raspberry pi
Re: interfacing coin acceptor to raspberry pi
Re: interfacing coin acceptor to raspberry pi
adafruit_support_rick wrote:dev64 wrote:What if the coin line was running at 5v, I could then simply power the pi with the coin line? I should probably determine what voltage is coming out of the coin line using a voltmeter. Can I power and read coin input from the coin line? that would be great! I also need some jumper cables for use with gpios.
The coin line is a signal line. You can't power anything with it.
You can't determine the voltage level of the coin line signal with a voltmeter, as it only carries a few 40 ms pulses when a coin is inserted.dev64 wrote:On the other hand, this looks more promising and safer way to power the pi
http://www.ebay.com/itm/DC-Converter-St ... 1203074650
That would work.dev64 wrote:Is there a more elegant way to splice the coin line, i did rather buy a line splitter or a divider. I did rather not go down the path of resistors, the approach seems a bit too hackish.
It's not hackish. You have to reduce the signal level to 3.3V somehow. That's the easiest way.
The coin line is a signal line. You can't power anything with it.
Re: interfacing coin acceptor to raspberry pi
Re: interfacing coin acceptor to raspberry pi
Re: interfacing coin acceptor to raspberry pi
Re: interfacing coin acceptor to raspberry pi