Raspberry Pi RASPIVEND, Quick Reference

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I. General informations
1. Terms
- RASPIVEND = Raspberry PI vending board (shield).
- RASPIVEND DAEMON - xinetd based RASPIVEND management daemon.
- MDB PERIPHERALS = payment systems connected on the MDB bus.
- CCTALK PERIPHERALS = payment systems and peripherals, connectod to ccTalk bus.
- HOST APPLICATION = the application executed by the xinetd superserver installed on
the Raspberry PI
-
CLIENT APLICATION = the client application that will connect to the socket of the HOST
APPLICATION
-
LOW LEVEL APPLICATION = the application that can directly communicate using
Raspberry PI serial port (/dev/ttyAMA0) and also can handle it's GPIO pins.
-
ACK = acknowledge
- NACK = not-acknowledge
RASPIVEND board and RASPIVEND daemon, toghether with VTLCOMBUS keyboard
simulator module, can be used to upgrade any Necta hot and universal machines and alos
any Wurlitzer universal spring machine.
2. Working modes
The RASPIVEND can be used to communicate with peripherals using two methods:
a. A low level communication method that can offer access to all peripherals by the
Raspberry PI serial port (/dev/ttyAMA0) and using 3 of it's GPIO to handle the multiplexers
to select the proper communication channel.
b. A high level communication method that simplifies the user interface development,
offering a language independent support.
A. Low level mode
In low level mode, there are simple commands to manage the MDB devices. The built-in
firmware will handle MDB commands and it is the ideal mode where the developers don't
need to learn any MDB command and response. Also there is no need to calculate the
MDB checksum since this is automatically calculated by the RASPIVEND and correctly
sent to the MDB peripheral. When the RASPIVEND will receive a low level command, it
automatically turn low level mode ON and begin to continuously poll the MDB
PERIPHERALS.
In this mode, there is no limit accessing any other peripheral and the LOW LEVEL
APPLICATION (created by the user) has the entire responsibility of multiplexer controls pin
manipulation by using the appropriate GPIO. The only channel that is automatically
selected is the MDB channel, which is selected every time a MDB low level command is
sent to the board (see page 9 for pin usage).
A proprietary simple message structure is available to communicate with bill validators,
coin acceptors/changers and cashless devices. The general message format is detailed in
table 1.
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