First of all, thank you to everyone in the arduino forums. I've done some really fun stuff and am having a great time learning. This is my first question to the forum (long time listener, first time caller).
I am attempting to use my arduino (2009) to communicate with a bill validator (sometimes called a bill acceptor) and a coin mechanism using the MDB protocol. The arduino will be the master and the two devices will be slaves.
To power the two devices (ranges of 20VDC to 34VDC), I've cut a laptop power adapter and spliced in.
To communicate with the devices, thats my trouble.... I am using the NewSoftSerial for the rx/tx with the two devices. MDB is supposed to be a bus but I'm trying to break it up onto two pins.
When I turn the devices on, I will get a byte of 1's for each device. So I'm thinking that I have everything setup to listen. I'm not getting any response when I send the following: 00110000
00110 is the bill validator (address is b3 through b7) and 000 is the command RESET (command is b0 through b2)
MDB is 9bit and with this extra bit setting the mode (mode is either 1 for an address byte or 0 for data) - I've tried to send it at the start or end with no luck.
A detaied run through of the protocol can be found on section 2 and the bill validators are on section 6:http://vending.org/technology/MDB_Version_4-2.pdf
Outside of not speaking the MDB language correctly, my only other thought is that I'm not being heard when sending from the arduino to bill validator. According to 4.2 - Buss tx/rx specs, a peripheral slave (bill validator) max input current is 15mA@4V and min sink current is 15mA@1V. I've tried with and without a resistor to take the arduino's sending to slightly below 15mA and still hasn't made a difference.
I'm okay with code(over one year), but still learning on the electronics/current side (no experience).
If anyone can shed some/any light on the problem (rather specific), it would be awesome. Outside of a couple mentions from kegbot makers, I haven't found much on the topic of MDB and arduino. Thanks everyone