JVS IO

JVS ArduinIO

This is a WIP library for communicating over the JVS protocol in Arduino compatible boards. This library supports both host mode and device mode. It requires one hardware UART to work connected to an RS485 transceiver such as the MAX RS485 TTL converter module.

A host can only have 1 input port per instance, a device must have 1 ouput port but may optionally have an input port for daisy chaning IO devices. The data lines are connected between ports, the sense line must connect to an output for the output port and an input for the input port. You will also need to connect the sense pin to pin 1 of USB-A connector.

Hardware

Device mode

This library requires a MAX485 transceiver or equivalent connected to the serial port RX and TX pins. You also need to specify an RTS (Request to Send) pin which is connected to both DE and ~RE.

Finally, you will either need a transistor (BC547 or 2n2222 or eqv.) for pulling the sense line low; whilst you can use the IO pin directly, it is better practice to do it this way to protect your MCU and the library would need to be changed to uninvert the pin. The sense line needs to be at 2.5v with the ID unset, and it's recomended to use 4x 1n4007 diodes from the sense line to ground to acheive this but users have reported a 1K resistor will also work - This will depend entirely on the host you are using.

Optionally you can specify a sense input line but this isn't unless you are supporting daisy chaining. If you are, you need a way to automatically terminate or remove the termination resistors from the bus. The bus must be terminated if there is no secondary IO board attached. It must not be terminated if there is a secondary IO board attached to your device.

Here is an example with downstream IO sensing which is needed for daisychaining.

Host mode

In host mode, it is advised to use an LM393 opamp to handle 5V, 2.5v and 0v sensing. This allows one to use either two pin or one pin to sense IO status (present with/out ID, not present). Otherwise, you can connect this to a GPIO pin, perhaps use a 220Ω resistor in line for over current protection.

Sensing

Depending on how you want to sense IO boards, you will need to consider different methods of sensing the IO board attached.

The SEGA/Nintendo/Namco Triforce does single pin sensing which is good enough for most use cases:

Another option is to remove the buffer gate and use two pins for better sensing. This allows one to know exactly the state of the sense in pin, be it IO board not connected, IO is present with no ID or present and ID'd. The SEGA Chihiro uses a verison of this sensing:

Usage

To use the library, include it before setup and then declare an instance by passing a UART port and the sense pin input/output. On Arduino UNO this will be Serial, but on board with multiple serial ports, you can use Serial2, Serial 3 etc. You cannot use SerialUSB. Note you can only have one instance at one time.

#include "jvs.h"
JVS jvs(Serial, 2, 3);     // HardwareSerial port, Sense pin, RTS pin

Once delcared, you will then need to run the initialization routines at startup either as a host node or a device node.

// Init as Device
void setup(){
    jvs.begin(DEVICE_NODE);    // Begin as device node
    jvs.initDevice();
}

// Init as Host
void setup(){
    jvs.begin(HOST_NODE);    // Begin as host node
    int found = jvs.initHost();       // Will hang here until devices are assigned or there is no JVS nodes. Returns number of JVS nodes
    //Serial1.print("Found: ");
    //Serial1.print(found);
    //Serial1.println(" nodes");
}

Then you will need to put update() in your loop. This is so you can receive packets from the IO board. You can have the JVS library run command codes, so long as it's in device mode and have set the iput/output data arrays:

void loop(){
    if(jvs.update()){
        jvs.runCommand();
    }
}

Or you can read the data in manually:

void loop(){
    if(jvs.update()){
        JVS_Frame inFrame;      // Frame in
        inFrame = jvs.read();   // Read frame into buffer
    }
}

Data Storage/JVS Frame layout

The data for commands and arguments is stored in JVS_Frame.data:

struct JVS_Frame {
    uint8_t sync = 0xE0;            // Sync is always E0
    uint8_t nodeID = 0;             // Node that frame is intended for, 0xFF is a boradcast frame
    uint8_t numBytes = 0;           // Includes all subsequent bytes (Status, data and sum) in frame after this byte
    uint8_t statusCode = 1;
    union{
        uint8_t data [254] = {0};   // Is command and parameters from host, report and results from device
        uint16_t data16 [127];      // Some parameters are 16-bit ints
        char dataString [102];      // When reading node IDs, they are stored as ASCII
    } ;
    uint8_t sum = 0;                // Checksum of ID, numbytes, data bytes
    uint8_t cmdCount = 1;           // Number of commands counted. Only counts standard commands (not manufacturer specific)
};

JVS Info

Both host and device nodes will need some data to report back when requested. The host needs the game name filled in where as devices need to report their name and what features it supports. If no data is supplied, it is prefilled with generic data. Note: When set as device, _ident is used where as _mainID is used when set to host. It's worth noting that only Namco games/devices seem to care about the main board ID, you can choose to support it or not, but Namco games might not be happy if you don't support it.

The library supports storing JVS IO board data in the following struct. This can be used for multiple IO boards by delcaring an array.

struct JVS_Info {
    char ident[100] = {"JVS ArduinIO;github.com/NaokiS28/jvs;VER:0.1 Beta"};
    char mainID[100] = {"ArduinoIO Host;github.com/NaokiS28/jvs;VER:0.1 Beta"};
    uint8_t cmdRev = 11;            // Stored as BCD, some JVS hosts (Triforce) will report ver 0.0 if it's higher than 1.1
    uint8_t jvsRev = 30;            // Stored as BCD, JVS rev. 20 and 30 are valid
    uint8_t comRev = 10;            // Stored as BCD, use 10 unless you need to otherwise
    uint8_t totalFeatures = 4;      // How many features supported, this isnt sent to the host but for the library
    featureTypes featureSupport[16] = {
        switchInput, coinInput, analogInput, gpOutput       // Supported features. These are listed in jvs_message.h
    };
    uint8_t featureParameters[16][3] = {                    // Parameters for the list of supported features.
        {2, 12, 0},     // Is switchInput in generic construction
        {2, 0, 0},      // 2 Coin slots
        {6, 10, 0},     // 6 ADCs, 10-Bit resolution
        {8, 0, 0}       // 8 GPOs (general purpose output)
    };
};