Overhauled readme and added protocol and wiring information
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Gregor Riepl
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README.md
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README.md
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@ -2,37 +2,33 @@
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The Matemat is a vending machine for carbonated soft drinks.
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It is based on an old vending machine with all its
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electronics replaced by new custom-build circuit boards.
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It is based on an old vending machine with all its electronics replaced by new
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custom-build circuit boards.
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All hardware and software was designed by members of
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[CCC Basel](http://www.ccc-basel.ch) and released in the
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form of circuit diagrams, printed circuit board layouts
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and source code for anyone to use and modify. Refer to
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the LICENSE file for details.
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[CCC Basel](http://www.ccc-basel.ch) and released in the form of circuit
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diagrams, printed circuit board layouts and source code for anyone to use and
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modify. Refer to the LICENSE file for details.
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The name "Matemat" is a portmanteau of "mate" (as in mate
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tea) and "automat" (the German word for vending machine).
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The device is mainly intended to dispense mate tea based
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soft drinks, but may be used for other types of beverages
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too.
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The name "Matemat" is a portmanteau of "mate" (as in mate tea) and "automat"
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(the German word for vending machine). The device is mainly intended to dispense
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mate tea based soft drinks, but may be used for other types of beverages too.
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## Structure
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The heart of the vending machine is a Raspberry Pi
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model 3 or later, witch a custom CAN interface board
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on its GPIO header.
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The heart of the vending machine is a Raspberry Pi model 3 or zero or later,
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with a custom CAN interface board on its GPIO header.
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See [CAN Hat](https://github.com/onitake/canhat) for
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more information.
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See [CAN Hat](https://github.com/onitake/canhat) for more information.
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## Firmware
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Some of the modules require firmware. There is a makefile in
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each module to build and flash it to its microcontroller.
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Some of the modules require firmware. There is a makefile in each module's
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firmware directory to build and flash the firmware to the integrated
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microcontroller
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Before building, you need to check out the CAN driver
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source code, which is referenced as a Git submodule.
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Before building, you need to check out the CAN driver source code, which is
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referenced as a Git submodule.
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Run the following commands in the checked out repository:
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@ -43,24 +39,22 @@ git submodule update
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## Modules
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The Matemat components are highly modular. Individual
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circuits are connected by CAN bus, and can be extended
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as needed.
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The Matemat components are highly modular. Individual circuits are connected by
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CAN bus, and can be extended as needed.
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### drive
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Single-motor driver.
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Attached directly to each bottle release mechanism.
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Requires only power supply wires for the motor and the
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CAN bus line.
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Attached directly to each bottle release mechanism. Requires only power supply
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wires for the motor and the CAN bus line.
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### power
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Motor driver board and power supply.
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Alternative to the drive board. Uses the existing machine
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wiring instead of power + CAN.
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Alternative to the drive board. Uses the existing machine wiring instead of
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power + CAN.
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### control
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@ -70,23 +64,14 @@ Old central control board. Obsolete.
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End switch feedback interface.
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Senses the status of the end switches and sends CAN bus
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messages on changes.
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Senses the status of the end switches and sends CAN bus messages on changes.
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### poweriface
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Interface between CAN bus and power board.
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This module requires firmware. Switch into the firmware
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directory `poweriface/firmware/` and run
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```shell
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make
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```
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To flash the firmware, attach a programmer to the ISP
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header on the PCB, then run:
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This module requires firmware. Connect an Atmel programmer to the ISP header,
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change into the firmware directory `poweriface/firmware/` and run:
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```shell
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make flash
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@ -99,3 +84,54 @@ Environment sensor interface.
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### wiring
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Wring schema of the old vending machine.
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## Bus
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### Topology
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All modules are connected via a CAN bus. It is highly recommended to wire them
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by means of shielded twisted-pair cable with a nominal impedance of 120Ω.
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At the very least, you need a cable with three wires to ensure a good ground
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connection between all modules.
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To allow for easy wiring, six-pole screw terminals are mounted to the PCBs.
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Two poles are intended for the positive CAN bus line, two for the negative line
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and two for the shield. They are internally connected together.
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### Wiring
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To achieve a continuous bus topology, connect only two cables to each module.
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Make sure CAN H is connected to CAN H and CAN L to CAN L. Crossover is not
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supported on the CAN bus. When wiring is complete, you should end up with a
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continuous bus that is tapped at each module. Attach 120Ω resistors (preferably
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1% or better) to the ends of the bus.
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The final wiring should look like this:
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```
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┌───────────┐ ┌───────────┐ ┌───────────┐
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│ module1 │ │ module2 │ │ module3 │
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│ │ │ │ │ │
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│H L ⏚ H L ⏚│ │H L ⏚ H L ⏚│ │H L ⏚ H L ⏚│
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└╥─╥─╥─╥─╥─╥┘ └╥─╥─╥─╥─╥─╥┘ └╥─╥─╥─╥─╥─╥┘
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╰━╯ └╥┘╱ └╥┘╱ └╥┘╱ └╥┘╱ ╰━╯
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120Ω ║╱ ║╱ ║╱ ║╱ 120Ω
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╚═════════╝ ╚═════════╝
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```
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### Protocol
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Bus communication only makes use of basic CAN features. No higher-level
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protocols such as CiA, EtherCAN, VSCP or similar are required.
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Extended 29-bit CAN adressing mode is used.
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This is the list of supported message IDs:
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| Message ID | Sender | Receiver | Data Length | Data Format | Description |
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|------------|------------|------------|-------------|-------------------------|-------------|
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| 0x1000 | controller | poweriface | 1 | 0b00000MMM | Start dispensing from slot M (0-5) |
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| 0x100 | any | poweriface | 0 | | Send power board status report |
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| 0x100 | any | sensor | 0 | | Send sensor board status report |
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| 0x10 | poweriface | controller | 2 | 0xLL 0xHH | Power board status report (0xHHLL are the contents of the 16-bit shift register) |
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| 0x1 | sensor | controller | 2 | 0bABCDEFGH 0b00000IJK | Sensor board status report (ABCDEFGHIJK are the states of the end switches, dispenser empty switches and the rest switch) |
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