Troubles with understanding of MDB sniffer

[Anonymous]

Hello, Dan!

You wrote a great library for mdb devices, named MDB sniffer: https://github.com/MarginallyClever/MDB-Sniffer

I have a questions about it. It will be great if you’ll help me.

1. Why do you use 2 arduinos instead of 1 arduino mega? It has 4 usarts and can interact simultaneously with mdb & raspberry pi.
2. How can I send a data to the bus? I see the MDB_transmitData method, but I not found any example of it’s usage. Can you give me a samples of the code?

[Anonymous]

I had two UNOs available. I needed hardware serial for the MDB *and* hardware serial to talk to my PC. So I used software serial between two arduino UNOs. Convoluted, but it worked.

I haven’t used transmit yet, I was still trying to figure out who was saying what and when. It’s easy to tell when the master talks to the slaves and hard to tell the reverse, especially if there’s any kind of communication failure.

Do you have a better way to do this?

[Anonymous]

Hi,

I was searchin gthe internet for a way to connect a computer to a vending machine when i came across your solution.
Instead of the 2 arduinos, i wanted to use a usb-rs232 with a din 5pin adapter. But i can’t get it to work, maybe it’s the 9bit problem, when the rs232 usually only goes to 8bit. Can you help, please?

My idea is to setup a computer, to check/manage stock and to accept other forms of payments, like paypal. And then “drop” the correct item.

Thanks

[Dan]

you already know your method won’t work.

You can’t drop the correct item. There is no way in MDB to say “drop item X”. you can only put or remove $X credit on the machine.

[Anonymous]

Thank you for the quick reply.

Thought it could be done with somekind of an adapter (the comunication part). Maybe with an ethernet shield on a arduino and then the arduino connected to the machine. By the way, i’m trying to connect via a 5pin din plug not with the 4 pin mdb plug. Not sure if there is any difference or is just an adapter. And also, the company who provided the machine installed a dex software/program.

But i guess it’s easier to strip the machine of the controller and create a new from a raspberry.

[Author]

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