JVSCore

JVSCore is a user space driver for using JVS I/O boards with Linux. It requires a USB RS485 converter wired to the JVS I/O.

The JVSCore device driver currently supports the following features of a JVS I/O:

Coins
Switches
Analogue Inputs

Installation

Installation is done from the git repository as follows:

sudo apt install build-essential cmake git
git clone https://github.com/bobbydilley/JVSCore
cd JVSCore
make
sudo make install

Cable

I'd recommend watching the below video from the TecknoGods about how to create a JVS cable.

https://www.youtube.com/watch?v=kqXEYtvGzno

RS485 Adapter Side	USB To Arcade Side
B-	DATA- (White)
A+	DATA+ (Green)
Not Required	VCC (Red)
GND	GND (Black)

Command Line Usage

To start JVSCore in the terminal to view debug messages, you can start it by typing the following:

sudo jvscore

There are various command line arguments that can be used to configure JVSCore. If running in the background as a service, these can be changed with the settings file as well.

Options:
	--disable-analogue     Disables analogue reading
	--analogue-fuzz        Specifies the analogue fuzz value
	--device-path          Specifies the RS485 device path

Settings file

All settings can be set by changing values in the /etc/jvscore.conf settings file.

The default RS485 converter device path can be changed using the DEVICE_PATH keyword.
The default analogue fuzz value can be changed using the ANALOGUE_FUZZ keyword. Fuzz is how much the analogue value has to change by before it is reported to the computer. This is useful if you've got super noisy pots on your controllers!
Enabling and disabling of analogue controls can be done with the ENABLE_ANALOGUE keyword, and 1 or 0 as the value. JVSCore will run faster with analogue controls disabled.

Systemd Service

If you'd like JVSCore to run in the background, and automatically connect to JVS I/O boards you can set it to run as a service. To do so type the following:

sudo systemctl enable jvscore
sudo systemctl start jvscore

JVSCore will constantly look for new JVS I/O devices (up to a maximum of 1) every minute and when these are found will create a joystick device. Once the JVS I/O is unplugged or switched off the joystick device will disappear.

To view the logs that JVSCore creates while running as a service, type the following:

sudo journalctl -u jvscore

Adapters known to work

The best adapters are those with an FTDI chipset.

Latency Testing

Thanks to JaviRodasG for testing the latency of JVSCore.

Results for JVSCore with analogue controls enabled are as follows:

15.14 - 15.80  [  9]  **
15.80 - 16.46  [ 35]  ********
16.46 - 17.11  [116]  ***************************
17.11 - 17.77  [158]  ************************************
17.77 - 18.43  [128]  ******************************
18.43 - 19.08  [161]  *************************************
19.08 - 19.74  [167]  **************************************
19.74 - 20.40  [137]  ********************************
20.40 - 21.06  [165]  **************************************
21.06 - 21.71  [147]  **********************************
21.71 - 22.37  [148]  **********************************
22.37 - 23.03  [176]  ****************************************
23.03 - 23.68  [144]  *********************************
23.68 - 24.34  [145]  *********************************
24.34 - 25.00  [164]  **************************************

Samples: 2000 of 2000
Average: 20.7348 ms
Maximum: 24.997 ms
Minimum: 15.143 ms
Std-dev: 2.4883 ms

Results for JVSCore without analogue controls enabled are as follows:

12.29 - 12.75  [ 32]  ********
12.75 - 13.20  [ 72]  *****************
13.20 - 13.66  [101]  ***********************
13.66 - 14.12  [114]  **************************
14.12 - 14.58  [141]  ********************************
14.58 - 15.04  [179]  ****************************************
15.04 - 15.50  [158]  ************************************
15.50 - 15.96  [151]  **********************************
15.96 - 16.41  [141]  ********************************
16.41 - 16.87  [159]  ************************************
16.87 - 17.33  [162]  *************************************
17.33 - 17.79  [128]  *****************************
17.79 - 18.25  [162]  *************************************
18.25 - 18.71  [126]  *****************************
18.71 - 19.17  [ 94]  *********************
19.17 - 19.63  [ 58]  *************
19.63 - 20.08  [ 22]  *****

Samples: 2000 of 2000
Average: 16.1385 ms
Maximum: 20.084 ms
Minimum: 12.287 ms
Std-dev: 1.8312 ms

Credits

Thank you very much to @chunksin and @JaviRodasG for helping to test and debug issues with the software!